Annual report on surveillance for avian influenza in poultry and wild birds in Member States of the European Union in 2021.

European Union (EU) Member States (MSs) are required to carry out surveillance for avian influenza (AI) in poultry and wild birds and notify the results to the responsible authority. In addition, Iceland, Norway, Switzerland and the United Kingdom (Northern Ireland) also implement ongoing surveillance programmes to monitor incursions of avian influenza viruses (AIVs) in poultry and wild birds. EFSA received a mandate from the European Commission to collate, validate, analyse and summarise the data resulting from these AI surveillance programmes in an annual report. The present report summarises the results of the surveillance activities carried out in MSs and the aforementioned countries in 2021. Overall, 24,290 poultry establishments (PEs) were sampled, of which 27 were seropositive for influenza A(H5) and 4 for A(H7) viruses. Seropositive PEs were found in 10 MSs and, as per previous years, the highest percentages of seropositive PEs were found in establishments raising waterfowl game birds and breeding geese. Out of these 31 seropositive PEs, 3 tested positive by polymerase chain reaction (PCR) for influenza A(H5) viruses: 1 for highly pathogenic avian influenza virus (HPAIV), 1 for low pathogenic avian influenza virus (LPAIV) and 1 with unknown virus pathogenicity. In addition, 16 countries reported PCR test results from 1,858 PEs which did not correspond to the follow-up testing of a positive serology event (e.g. in some PEs, PCR tests were used for screening). Sixty-five of these PEs in 10 MSs were found positive for AIVs. Apart from poultry, 31,382 wild birds were sampled, with 2,314 wild birds testing positive for HPAIVs by PCR. Twenty-two countries reported HPAIV-positive wild birds and most positive samples were identified as highly pathogenic avian influenza (HPAI) A(H5N8) virus. In addition, 328 wild birds tested positive for LPAIVs of the A(H5/H7) subtypes and 362 wild birds tested positive for non-A(H5/H7) subtype AIVs.

Summary

The European Union (EU) Member States (MSs), Iceland, Norway, Switzerland and the United Kingdom (Northern Ireland)1 (together referred to as reporting countries, RCs) implement surveillance programmes to detect incursions of avian influenza viruses (AIVs) in poultry and wild birds, particularly migratory wild birds, which are considered the main source of introduction of AIVs into poultry establishments (PEs). The present report summarises the results of the EU co‐funded surveillance activities conducted in 2021, which consisted of:

serological surveys to monitor the circulation of AIVs (A(H5) and A(H7) subtypes) in poultry and follow‐up testing of positive serology events by polymerase chain reaction (PCR) (active surveillance).

detection of AIVs in wild birds found dead or moribund by PCR (passive surveillance).

In addition, some MSs reported results from PCR tests conducted in poultry as part of active surveillance which did not relate to the aforementioned follow‐up testing (e.g. screening) and results of active surveillance activities performed by testing live and hunted wild birds.

It is important to note that risk‐based sampling strategies used for AI surveillance may vary between countries. Therefore, comparisons of positivity rates between different groups, such as different poultry categories, presented in this report are not representative and relate to the specific surveillance samples only. Positivity rates cannot be extrapolated to the source populations, as sampling may have targeted higher‐risk groups. Moreover, the targeting approach may be different between countries, between groups and between years.

Changes in prevalence or incidence may not be fully captured by risk‐based surveillance programmes only. Therefore, the differences in AI incidence between countries observed in this report, both in poultry and wild birds, should be interpreted with caution. Direct comparisons between countries should be avoided.

Serological surveys in poultry

A total of 31 RCs reported data on sampling and AI testing in PEs. In some RCs, the same PEs were sampled several times throughout the year. For the purpose of this report, each sampling event taking place on a specific date and targeting a specific poultry category was considered an independent event and counted as one PE sampled. Therefore, the numbers reported in this report as ‘PEs sampled’ should be interpreted as the number of sampling events taking place in a RC for each of the reported poultry categories.

Figures on the size of the poultry population (e.g. the overall number of PEs) under surveillance in RCs were not available when writing the present report. In 2021, a total of 24,290 PEs were sampled, slightly less than the number of PEs sampled in the previous year. The total number of PEs sampled and reported in each RC ranged from 20 in Hungary to 5,144 in the Netherlands.

Seventeen poultry categories (Table A.1 in Appendix A) were created to summarise the surveillance results in the present report. None of them was fully covered and sampled by all RCs. However, laying hen (conventional and free‐range), breeding chicken, fattening turkey and gallinaceous game bird establishments were sampled by at least 20 RCs each. Growers and Muscovy ducks were targeted by only three and two RCs, respectively. In terms of the number of PEs sampled, backyard flocks were the most frequently sampled poultry category (n = 4,683), followed by conventional and free‐range laying hens (n = 4,433 and 3,435, respectively).

Table A.1

Total number of PEs sampled and testing positive in 2021, according to the 17 poultry categories used in this report and the detailed reporting categories available to MSs

Reporting category used in this report	Detailed reporting category	Number of sampling events	Number of A(H5/H7)‐ positive events
Laying hens	Laying hens	4,433	45
Free‐range laying hens	Free‐range laying hens	3,435	55
Breeding chickens	Breeding chickens	2,594	51
Broilers (heightened risk)	Broilers	1,093	1
	Free‐range broilers	219	0
Breeding turkeys	Breeding turkeys	175	7
Fattening turkeys	Fattening turkeys	2,181	8
	Free‐range fattening turkeys	6	1
Breeding ducks	Breeding ducks	206	9
	Ducks	6	1
Fattening ducks	Fattening ducks	913	27
	Free‐range fattening ducks	27	0
Breeding geese	Breeding geese	142	6
Fattening geese	Fattening geese	326	10
	Free‐range fattening geese	37	0
Growers	Chickens	33	0
	Ducks	9	0
	Generic poultry	2,217	0
	Turkeys	1	0
Backyard flocks	Backyard	4,683	54
Muscovy ducks	Muscovy ducks	4	0
Game birds (gallinaceous)	Farmed game birds (Gallinaceous)	315	5
	Free‐range pheasants	1	0
	Guinea‐fowl	17	0
	Partridges	44	2
	Pheasants	120	0
	Quails	41	0
Game birds (waterfowl)	Farmed game birds (Waterfowl)	130	34
	Mallard ducks	9	1
Ratites	Free‐range ostriches	17	0
	Ostriches	42	0
	Ratites	63	2
Others	Chickens	167	19
	Ducks	540	3
	Geese	11	0
	Other	22	0
	Turkeys	11	0

A total of 31 PEs were seropositive for either influenza A(H5) or A(H7) viruses (hereinafter referred to as A(H5/H7) viruses), including 27 to A(H5) and 4 to A(H7) subtypes. The H5/H7 seropositivity rate (0.13%) was around half of the one observed in 2020 (0.21%). Ten countries reported A(H5)‐seropositive PEs: Belgium, Bulgaria, Czechia, Denmark, Finland, France, Italy, Poland, Spain and Sweden. Spain and France also reported A(H7)‐seropositive PEs. Italy, the Netherlands and Romania accounted for more than 60% of all reported PEs sampled, however, only one positive PE was found among those PEs. The 2021 results confirm an overall decreasing trend in the proportion of A(H5/H7)‐seropositive establishments reported to EFSA since the 2016 HPAI A(H5Nx) outbreaks, with the significant exception of 2019. The number of A(H5)‐seropositive PEs remained higher than the number of A(H7)‐seropositive PEs, as per previous years.

Similarly, waterfowl game birds and breeding geese were the poultry categories with the largest proportions of A(H5/H7)‐seropositive establishments (7.9% and 3.5%, respectively). The proportion of A(H5/H7)‐seropositive PEs was 2.8% in breeding duck establishments and below 1% in all other poultry categories. No positive PEs were found in the following poultry categories: breeding chickens, broilers (heightened risk), turkeys (fattening and breeding), growers and Muscovy ducks. While backyard flocks and laying hens (conventional and free‐range) represented the most frequently tested poultry categories, only 3, 1 and 1 seropositive PEs were identified, respectively. May was the month with the highest seropositive rate, followed by December.

In addition, serological test results for other AIVs than A(H5/H7) subtypes were available for some PEs. However, due to the non‐mandatory reporting of these subtypes, the results presented in this report are less likely to be representative. Moreover, 16 countries also reported PCR test results carried out as screening tests from 1,858 PEs. Sixty‐five of these PEs were found positive for AIVs and were located in Belgium, Bulgaria, Estonia, Germany, Italy, Lithuania, Luxembourg, Norway, Romania and Slovakia. Only 16 PEs were positive for HPAI A(H5) viruses and were located in Bulgaria, Estonia, Germany and Norway.

In order to optimise the information provided by active surveillance in poultry, RCs are encouraged to report the link between seropositive PEs and the results of further follow‐up sampling and/or testing carried out in the same or surrounding PEs. Finally, understanding the distribution and composition of the underlying poultry population will help to better evaluate the efficiency of the surveillance activities carried out at a European level.

Surveillance in wild birds

A total of 27 MSs, Iceland, Norway, Switzerland and the United Kingdom (Northern Ireland) reported results from passive surveillance of AIVs in wild birds in 2021. Although non‐mandatory, 12 countries also reported results from their active surveillance programmes. Surveillance in wild birds in most RCs is not based on representative sampling, which is why the results presented here cannot be extrapolated to the source populations. Comparisons are valid for the specific surveillance samples only and cannot be used to imply differences between species, between locations or between years.

Results were reported for a total of 31,382 wild birds, including 20,920 wild birds sampled by passive surveillance. Compared to 2020, the total number of wild birds sampled in 2021 was larger due to a greater contribution of passive surveillance. Within RCs, the numbers of wild birds sampled by passive surveillance ranged from 9 wild birds in Malta to 7,321 wild birds in Germany. As results from active surveillance programmes in wild birds are only reported to EFSA on a non‐mandatory basis, the numbers presented in this report do not necessarily reflect the full extent of active surveillance activities conducted by the RCs.

The number of wild birds sampled by quarter was much larger in the first quarter of 2021, from January to March, compared to the rest of the year (43% of the total). The monthly distribution of sampling within RCs was highly variable. Only half of all wild birds sampled were fully identified at species level (16,615 birds). These wild birds belonged to 294 species distributed in 7 orders. The largest number of samples originated from wild birds of the order Anseriformes (n = 6,302). The orders Passeriformes, Accipitriformes, Charadriiformes, Columbiformes, Pelecaniformes and Strigiformes were also sampled in large numbers (n > 1,000 each). Forty‐seven of the 50 species listed by EFSA as targets for HPAI surveillance (Table E.1 in Appendix E) were sampled in 2021. The proportion of wild birds belonging to these target species was 41.4% and 34.7% among passive and active surveillance samples, respectively.

Table E.1

List of target wild bird species published in December 2017 (EFSA, ECDC and EURL, 2017b) (species not sampled in 2021 are highlighted in grey)

Family	Subfamily, tribe or genus	Species
Coots, crakes and rails (Rallidae)		Western swamphen (Porphyrio porphyrio)
Cormorants and shags (Phalacrocoracidae)		Great cormorant (Phalacrocorax carbo)
Corvids (Corvidae)		Eurasian magpie (Pica pica)
Ducks, geese and swans (Anatidae)	Dabbling ducks (Anatinae)	Eurasian teal (Anas crecca)
	Dabbling ducks (Anatinae)	Eurasian wigeon (Anas penelope)
	Dabbling ducks (Anatinae)	Gadwall (Anas strepera)
	Dabbling ducks (Anatinae)	Mallard (Anas platyrhynchos)
	Dabbling ducks (Anatinae)	Northern pintail (Anas acuta)
	Diving ducks (Aythyini)	Common pochard (Aythya ferina)
	Diving ducks (Aythyini)	Greater scaup (Aythya marila)
	Diving ducks (Aythyini)	Red‐crested pochard (Netta rufina)
	Diving ducks (Aythyini)	Tufted duck (Aythya fuligula)
	Sea ducks (Mergini)	Common eider (Somateria mollissima)
	Sea ducks (Mergini)	Common goldeneye (Bucephala clangula)
	Sea ducks (Mergini)	Goosander (Mergus merganser)
	Sea ducks (Mergini)	Smew (Mergus albellus)
	Shelducks and sheldgeese (Tadorninae)	Common shelduck (Tadorna tadorna)
	Shelducks and sheldgeese (Tadorninae)	Egyptian goose (Alopochen aegyptiacus)
	Swans (Cygnus sp.)	Black swan (Cygnus atratus)
	Swans (Cygnus sp.)	Mute swan (Cygnus olor)
	Swans (Cygnus sp.)	Whooper swan (Cygnus cygnus)
	True geese (Anser sp., Branta sp., Chen sp.)	Brant goose (Branta bernicla)
	True geese (Anser sp., Branta sp., Chen sp.)	Canada goose (Branta canadensis)
	True geese (Anser sp., Branta sp., Chen sp.)	Greater white‐fronted goose (Anser albifrons)
	True geese (Anser sp., Branta sp., Chen sp.)	Greylag goose (Anser anser)
	True geese (Anser sp., Branta sp., Chen sp.)	Lesser white‐fronted goose (Anser erythropus)
	True geese (Anser sp., Branta sp., Chen sp.)	Pink‐footed goose (Anser brachyrhynchus)
	True geese (Anser sp., Branta sp., Chen sp.)	Taiga bean Goose (Anser fabalis)
Grebes (Podicipedidae)		Black‐necked grebe (Podiceps nigricollis)
		Great crested grebe (Podiceps cristatus)
		Little grebe (Tachybaptus ruficollis)
Gulls, terns and allies (Laridae)		Black‐headed gull (Chroicocephalus ridibundus)
		European herring gull (Larus argentatus)
		Great black‐backed gull (Larus marinus)
		Mew gull (Larus canus)
Herons (Ardeidae)		Eurasian bittern (Botaurus stellaris)
		Great white egret (Egretta alba)
		Grey heron (Ardea cinerea)
		Little egret (Egretta garzetta)
Pelicans (Pelecanidae)		Dalmatian pelican (Pelecanus crispus)
		Great white pelican (Pelecanus onocrotalus)
Raptors (Accipitridae, Falconidae, Strigidae)		Common buzzard (Buteo buteo)
		Eurasian eagle‐owl (Bubo bubo)
		Northern goshawk (Accipiter gentilis)
		Peregrine falcon (Falco peregrinus)
		Rough‐legged buzzard (Buteo lagopus)
		White‐tailed eagle (Haliaeetus albicilla)
Sandpipers (Scolopacidae)		Green sandpiper (Tringa ochropus)
Storks (Ciconiidae)		White stork (Ciconia ciconia)
Thrushes (Turdidae)		Fieldfare (Turdus pilaris)

A total of 3,098 wild birds tested positive for AIVs: 2,314 for HPAIVs and 784 for LPAIVs. The largest number of HPAIV detections were identified as HPAI A(H5N8) viruses (1,321 out of 2,314 HPAIV‐positive wild birds). The three species with the largest proportions of HPAIV‐positive wild birds were the mute swan (Cygnus olor), the barnacle goose (Branta leucopsis) and the common buzzard (Buteo buteo). In general, HPAIVs in wild birds were identified at higher numbers and in larger proportions than in previous years (878 and 1 HPAIV‐positive wild birds reported in 2020 and 2019, respectively). HPAIV‐positive wild birds were reported by 22 countries: Austria, Belgium, Bulgaria, Croatia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, the Netherlands, Norway, Poland, Slovenia, Spain, Sweden, Switzerland and the United Kingdom (Northern Ireland).

HPAIV‐positive wild birds were mostly detected during the first and last quarters of the year. These results are in accordance with the seasonal fluctuations of the widespread HPAI A(H5N8) epidemic reported in Europe since late 2020, affecting both poultry and wild birds. The last major HPAI epidemic in Europe had been reported in 2016–2017. After a relatively low circulation of HPAIVs in Europe in 2018 and 2019, it appears that the risk significantly increased throughout the continent in late 2020 and remained high in the first quarter of 2021 before falling again in the following quarter. However, detection rates of HPAIVs increased again in the last quarter of 2021 after a typical seasonal low along the summer period.

The 784 LPAIV‐positive wild birds were reported by 22 of the 31 RCs. Positivity rates were the lowest in spring (March to August), while most LPAIV‐positive wild birds were detected from September onwards. Passive surveillance activities accounted for the majority of LPAIV detections (62%). Most LPAIV‐positive wild birds belonged to the order Anseriformes, which was expected given that this order was the most frequently sampled order by both active and passive surveillance programmes.

This report also presents summary data of wild bird observations by voluntary contributors in RCs obtained from the EuroBird Portal (EBP).2 Despite the limitations of such data, and until further spatial modelling of the abundance and distribution of wild birds in Europe is readily available, the maps presented in this report may help to shed some light on areas where wild birds of the species belonging to the EFSA target list (Table E.1 in Appendix E) may gather, supporting RCs in carrying out more targeted surveillance activities. Further maps of the distribution of the 50 target species and the numbers of samples taken by RCs for these target species by month and NUTS3 level have been provided in Zenodo (https://doi.org/10.5281/zenodo.7053222). Considering the seasonality associated with the circulation of AIVs, these maps may be of help in improving the timing of sampling for targeted surveillance activities.

Introduction

Since late 2020, several European countries have experienced severe outbreaks of AI in poultry, with the highest number of outbreaks reported in farmed ducks, due to the circulation of different HPAI A(H5) viruses in the EU. In addition to these HPAIVs identified over the years, LPAIVs of both A(H5/H7) (not classified as HPAIVs) and other subtypes are continuously isolated from both poultry and wild birds. In order to implement appropriate measures to prevent incursions of AIVs and control the spread of the disease when incursions occur, MSs have implemented surveillance programmes in poultry and wild birds, including serological and virological surveillance activities. These activities include sampling of biological materials from different origins, detection of AIVs by various laboratory methods and typing of different antigenic subtypes based on their surface glycoproteins: haemagglutinin (H) and neuraminidase (N). The development and implementation of these surveillance programmes is currently supported by Regulation (EU) 2016/4293, which lays down the rules related to the EU surveillance programme for avian influenza, with Commission Delegated Regulation (EU) 2020/6894 providing the technical requirements, such as objectives, scope and methodological principles.

Background and Terms of Reference

In 2017, EFSA received a mandate with the Terms of Reference being to ‘collect, collate, validate, analyse and summarise in an annual report the results from avian influenza surveillance carried out by Member States in poultry and wild birds’. In the context of Article 31 of Regulation (EC) No 178/20025, from 2019 onwards, EFSA was requested to provide technical and scientific assistance to the EC to deliver on this mandate. This implies that EFSA has been responsible for producing the annual surveillance report on AI since 2020. In addition, the collation of all data related to the surveillance activities taking place in MSs has been conducted by EFSA in a harmonised way since January 2019.

Results

Poultry

Number of poultry establishments sampled

Twenty‐seven MSs, Iceland, Norway, Switzerland and the United Kingdom (Northern Ireland), here referred to as RCs, reported results from their serological surveillance activities in 2021. Data on the total number of PEs present in RCs and the distribution of poultry categories within RCs were not available for this report. Therefore, the numbers of samples per poultry category reported below do not include information on the proportion of the population sampled in each RC and poultry category.

A total of 24,290 PEs6 were sampled as part of the RCs' surveillance programmes. In this report, the numbers reported as ‘PEs sampled’ should be treated with caution, as they refer to the total numbers of sampling events taking place in all PEs and on distinct dates for a specific poultry category (see Section 5 for further details). Thus, the numbers of distinct PEs where sampling was performed may be lower than the total numbers of PEs sampled mentioned in this report (i.e. some PEs may have been sampled more than once). Such definition of PEs was important, as not all RCs are submitting surveillance data in a non‐aggregated manner.

Surveillance in RCs varied in both the numbers of PEs sampled and the poultry categories targeted for surveillance (Figure 1). Some countries conducted testing in a limited number of poultry categories only (e.g. backyard flocks), while others distributed their sampling efforts over a larger number of poultry categories. An overview of the total numbers of PEs sampled by each RC and for each poultry category is provided in Figures 5A and 9A, respectively.

Figure 1

Total number of PEs sampled, presented by RC and poultry category, according to 17 poultry categories. The colours are used to indicate the poultry categories with the smallest (lightest blue shade) to the largest (darkest blue shade) number of PEs sampled within a given RC

For Czechia, the correct numbers of PEs sampled are: 28 PEs for Breeding Ducks, 8 PEs for Breeding Geese and 10 PEs for Game Birds (Waterfowl).

Figure 5

(A) Total number of PEs sampled in 2021 shown per RC in descending order and (B) total number of seropositive PEs found by subtype

For Czechia, the correct number of PEs sampled is 262.

Figure 9

(A) Total number of PEs sampled by poultry category with values above bars referring to the number of PEs sampled, (B) percentage (y‐axis) and number (above bars) of PEs sampled that tested seropositive for influenza A(H5/H7) viruses by poultry category

When looking at the poultry categories for which the largest numbers of samples were taken, backyard flocks as well as conventional and free‐range laying hens were the 3 most frequently sampled poultry categories (Figure 1). In addition, Figure 1 also shows the most frequently targeted poultry categories (i.e. tested by the largest number of RCs). There were 5 categories for which surveillance results were reported by at least 20 RCs: laying hens (conventional and free‐range), breeding chickens, fattening turkeys and gallinaceous game birds. Only 3 and 2 countries reported sample collection from growers7 and Muscovy ducks, respectively. Between 10 and 17 countries reported surveillance results for the remaining poultry categories (broilers at heightened risk, breeding turkeys, breeding and fattening ducks, breeding and fattening geese, backyard flocks, waterfowl game birds, ratites and others).

The mapping between the 17 reporting categories used in this report and the detailed reporting categories (for consistency with previous reports) is presented in Appendix A (Tables A.1 and A.2).

Table A.2

Detailed mapping of the 17 poultry categories used in this report and the detailed reporting categories available to MSs, comprising the species, production method and purpose of raising poultry

Reporting category used in this report	Detailed reporting category	Poultry species	Purpose of raising	Production method
Laying hens	Laying hens	Gallus gallus laying hens (as animal)	Breeding purpose	Not available
		Gallus gallus laying hens (as animal)	Not available	Not available
Free‐range laying hens	Free‐range laying hens	Gallus gallus laying hens (as animal)	Breeding purpose	Outdoor/free‐range growing condition
		Gallus gallus laying hens (as animal)	Not available	Outdoor/free‐range growing condition
Breeding chickens	Breeding chickens	Gallus gallus breeding flock (as animals)	Breeding purpose	Not available
		Gallus gallus breeding flock (as animals)	Not available	Not available
	Free‐range breeding chickens	Gallus gallus breeding flock (as animals)	Not available	Outdoor/free‐range growing condition
Broilers (heightened risk)	Broilers	Gallus gallus broiler (as animal)	Breeding purpose	Not available
		Gallus gallus broiler (as animal)	Meat production purpose	Not available
		Gallus gallus broiler (as animal)	Not available	Not available
	Free‐range broilers	Gallus gallus broiler (as animal)	Not available	Outdoor/free‐range growing condition
Breeding turkeys	Breeding turkeys	Turkey breeding flock (as animals)	Breeding purpose	Not available
		Turkey breeding flock (as animals)	Not available	Not available
Fattening turkeys	Fattening turkeys	Turkey fattening animal (as animal)	Breeding purpose	Not available
		Turkey fattening animal (as animal)	Meat production purpose	Not available
		Turkey fattening animal (as animal)	Not available	Not available
	Free‐range fattening turkeys	Turkey fattening animal (as animal)	Not available	Outdoor/free‐range growing condition
Breeding ducks	Breeding ducks	Duck breeding flock (as animals)	Breeding purpose	Not available
		Duck breeding flock (as animals)	Game purpose	Not available
		Duck breeding flock (as animals)	Not available	Not available
	Ducks	Duck (as animal)	Breeding purpose	Not available
		Duck laying hens (as animal)	Breeding purpose	Not available
Fattening ducks	Fattening ducks	Duck fattening animal (as animal)	Breeding purpose	Not available
		Duck fattening animal (as animal)	Game purpose	Not available
		Duck fattening animal (as animal)	Meat production purpose	Not available
		Duck fattening animal (as animal)	Not available	Not available
	Free‐range fattening ducks	Duck fattening animal (as animal)	Not available	Outdoor/free‐range growing condition
Breeding geese	Breeding geese	Goose breeding flock (as animals)	Breeding purpose	Not available
		Goose breeding flock (as animals)	Not available	Not available
	Free‐range breeding geese	Goose breeding flock (as animals)	Not available	Outdoor/free‐range growing condition
	Geese	Goose laying hens (as animal)	Breeding purpose	Not available
Fattening geese	Fattening geese	Goose fattening animal (as animal)	Meat production purpose	Not available
		Goose fattening animal (as animal)	Not available	Not available
	Free‐range fattening geese	Goose fattening animal (as animal)	Not available	Outdoor/free‐range growing condition
Growers	Chickens	Gallus gallus (chicken) (as animal)	Growers	Not available
	Ducks	Duck (as animal)	Growers	Not available
	Generic poultry	Generic poultry (as animal)	Growers	Not available
	Turkeys	Turkey (as animal)	Growers	Not available
Backyard flocks	Backyard	Anseriformes (as animal)	Not available	Backyard farming – growing
		Duck (as animal)	Breeding purpose	Backyard farming – growing
		Duck (as animal)	Growers	Backyard farming – growing
		Duck (as animal)	Meat production purpose	Backyard farming – growing
		Duck (as animal)	Not available	Backyard farming – growing
		Duck breeding flock (as animals)	Not available	Backyard farming – growing
		Duck fattening animal (as animal)	Not available	Backyard farming – growing
		Gallus gallus (chicken) (as animal)	Growers	Backyard farming – growing
		Gallus gallus (chicken) (as animal)	Not available	Backyard farming – growing
		Gallus gallus breeding flock (as animals)	Breeding purpose	Backyard farming – growing
		Gallus gallus breeding flock (as animals)	Not available	Backyard farming – growing
		Gallus gallus broiler (as animal)	Meat production purpose	Backyard farming – growing
		Gallus gallus broiler (as animal)	Not available	Backyard farming – growing
		Gallus gallus laying hens (as animal)	Breeding purpose	Backyard farming – growing
		Gallus gallus laying hens (as animal)	Not available	Backyard farming – growing
		Generic poultry (as animal)	Growers	Backyard farming – growing
		Generic poultry (as animal)	Not available	Backyard farming – growing
		Goose (as animal)	Not available	Backyard farming – growing
		Goose breeding flock (as animals)	Not available	Backyard farming – growing
		Goose fattening animal (as animal)	Not available	Backyard farming – growing
		Guinea‐fowl (as animal)	Not available	Backyard farming – growing
		Ostrich (as animal)	Not available	Backyard farming – growing
		Pheasant (as animal)	Breeding purpose	Backyard farming – growing
		Pheasant (as animal)	Game purpose	Backyard farming – growing
		Pheasant (as animal)	Not available	Backyard farming – growing
		Turkey (as animal)	Not available	Backyard farming – growing
		Turkey breeding flock (as animals)	Not available	Backyard farming – growing
		Turkey fattening animal (as animal)	Meat production purpose	Backyard farming – growing
		Turkey fattening animal (as animal)	Not available	Backyard farming – growing
Muscovy ducks	Muscovy ducks	Muscovy duck (as animal)	Not available	Not available
Game birds (gallinaceous)	Farmed game birds (gallinaceous)	Galliformes (as animal)	Game purpose	Not available
		Galliformes (as animal)	Not available	Not available
		Peafowl (as animal)	Not available	Not available
	Free‐range partridges	Partridge (as animal)	Game purpose	Outdoor/free‐range growing condition
	Free‐range pheasants	Pheasant (as animal)	Game purpose	Outdoor/free‐range growing condition
	Guinea‐fowl	Guinea‐fowl (as animal)	Not available	Not available
	Other	Game or wild bird (as animal)	Game purpose	Not available
	Partridges	Partridge (as animal)	Breeding purpose	Not available
		Partridge (as animal)	Game purpose	Not available
		Partridge (as animal)	Not available	Not available
		Partridge breeding flock (as animals)	Game purpose	Not available
		Partridge breeding flock (as animals)	Not available	Not available
		Partridge fattening animal (as animal)	Not available	Not available
	Pheasants	Pheasant (as animal)	Breeding purpose	Not available
		Pheasant (as animal)	Game purpose	Not available
		Pheasant (as animal)	Not available	Not available
		Pheasant breeding flock (as animals)	Breeding purpose	Not available
		Pheasant breeding flock (as animals)	Game purpose	Not available
		Pheasant breeding flock (as animals)	Not available	Not available
		Pheasant laying hens (as animal)	Not available	Not available
	Quails	Common quail (as animal)	Not available	Not available
		Grey partridge (as animal)	Not available	Not available
		Quail (as animal)	Breeding purpose	Not available
		Quail (as animal)	Not available	Not available
		Quail breeding flock (as animals)	Breeding purpose	Not available
		Quail fattening animal (as animal)	Not available	Not available
		Quail laying hens (as animal)	Not available	Not available
	Turkeys	Turkey (as animal)	Game purpose	Not available
Game birds (waterfowl)	Ducks	Duck (as animal)	Game purpose	Not available
	Farmed game birds (waterfowl)	Anas sp.(as animal)	Not available	Not available
		Anseriformes (as animal)	Game purpose	Not available
		Anseriformes (as animal)	Not available	Not available
		Anseriformes (as animal)	Not available	Outdoor/free‐range growing condition
		Common goldeneye (as animal)	Not available	Not available
		Velvet scoter (as animal)	Not available	Not available
		Wood duck (as animal)	Not available	Not available
	Free‐range mallard ducks	Mallard (as animal)	Game purpose	Outdoor/free‐range growing condition
	Mallard ducks	Mallard (as animal)	Game purpose	Not available
		Mallard (as animal)	Not available	Not available
Ratites	Free‐range ostriches	Ostrich (as animal)	Not available	Outdoor/free‐range growing condition
	Free‐range ratites	Ratite (as animal)	Not available	Outdoor/free‐range growing condition
	Ostriches	Ostrich (as animal)	Game purpose	Not available
		Ostrich (as animal)	Not available	Not available
		Ostrich breeding flock (as animals)	Not available	Not available
		Ostrich fattening animal (as animal)	Not available	Not available
	Other	Emu (as animal)	Not available	Not available
	Ratites	Ratite (as animal)	Not available	Not available
Others	Chickens	Gallus gallus (chicken) (as animal)	Not available	Not available
	Ducks	Duck (as animal)	Meat production purpose	Not available
		Duck (as animal)	Not available	Not available
		Duck laying hens (as animal)	Not available	Not available
	Free‐range chickens	Gallus gallus (chicken) (as animal)	Not available	Outdoor/free‐range growing condition
	Free‐range ducks	Duck (as animal)	Not available	Outdoor/free‐range growing condition
	Geese	Goose (as animal)	Not available	Not available
		Goose laying hens (as animal)	Not available	Not available
	Other	Cattle egret (as animal)	Not available	Not available
		Common cuckoo (as animal)	Not available	Not available
		Eurasian spoonbill (as animal)	Not available	Not available
		Falco (as animal)	Not available	Not available
		Greater flamingo (as animal)	Not available	Not available
		Pigeon (as animal)	Not available	Backyard farming – growing
		Pigeon (as animal)	Not available	Not available
		Saker falcon (as animal)	Not available	Not available
	Parrots	Parrots (as animal)	Not available	Not available
		Psittaciformes (as animal)	Not available	Backyard farming – growing
		Psittaciformes (as animal)	Not available	Not available
	Pigeon breeding flock	Pigeon breeding flock (as animals)	Not available	Not available
	Turkeys	Turkey (as animal)	Not available	Not available

In addition to the sampling carried out under European funding (‘EU co‐funded active surveillance’ in Figure 2), 4 MSs also reported surveillance results from their national programmes (non‐EU co‐funded programmes) (Estonia, Luxembourg, Slovakia and Spain) (Figure 2). It must be highlighted that MSs are not obliged to report surveillance results from surveillance activities other than the EU co‐funded active surveillance. Norway, Switzerland and Iceland reported results from their national programmes, with Iceland also reporting results obtained by private industry sampling.

Figure 2

Number of PEs sampled by RCs in 2021 according to the type of active surveillance programme for which results were reported to EFSA

For Czechia, the correct number of PEs sampled is 262.

Timing of sampling in poultry

In terms of timing of sampling in poultry, 52% of sampling took place in the second half of the year (July to December). All countries except one conducted sampling activities during both halves, while France concentrated all its sampling activities in the second half of the year. A total of 12,675 PEs were reported as sampled from July to December, while 11,615 PEs were reported as sampled from January to June 2021. Figure 3 shows the monthly distribution of sampling in poultry by RC.

Figure 3

Monthly number of PEs sampled by RCs in 2021, reflecting heterogeneity in sampling efforts. The scale of the vertical axes varies by RC

Avian influenza in poultry

Serological test results overview

In this section, comparisons of seropositivity rates between different groups relate to the sampled populations only. They cannot be extrapolated to the source populations, because:

sampling targeted higher‐risk groups (non‐representative sampling strategy) in some RCs.

the definition and prioritisation of higher‐risk groups may differ between RCs, between groups and between years.

Therefore, the percentages provided in this report relate to the surveillance samples only. The underlying population cannot be used as denominator. Interpretations of temporal trends are based on the assumption that both sampling strategies and targeting remain constant in all RCs throughout the year.

In 2021, 27 and 4 PEs were seropositive for influenza A(H5) and A(H7) viruses, respectively (Figure 4). None of the PEs sampled tested positive for both influenza A(H5) and A(H7) viruses. The combined percentage of A(H5/H7)‐seropositive PEs was 0.13%, which was lower than in 2020 (0.21%). The percentage of A(H5)‐seropositive PEs was 0.11%, which decreased by almost half compared to the previous year (0.19% in 2020). The percentage of A(H7)‐seropositive PEs was 0.02%, similar to the percentage found in 2020 (0.03%). In 2021, the total number of PEs sampled (n = 24,290) was at a similar level as in 2020 and 2019, but it was still higher than the numbers of PEs sampled between 2014 and 2018 (Figure 4A).

Figure 4

(A) Total number of PEs sampled per year and (B) line graph of the percentage of PEs seropositive for influenza A(H5/H7) viruses, with the number of seropositive PEs shown per year as labels

Serological test results by reporting countries

As per previous years, considerable variation in the number of PEs sampled was observed among RCs in 2021 (Figure 5). As in 2020, three countries (Italy, the Netherlands and Romania) accounted for 60% of all PEs sampled during the course of 2021. Variations were also observed within RCs (Figure 6). The total number of PEs sampled ranged from 20 in Hungary to 5,144 in the Netherlands, with the median number of PEs sampled in RCs being 267 (Figure 5). Between RCs, the numbers of A(H5/H7)‐seropositive PEs varied only slightly. A total of ten RCs reported the detection of A(H5/H7)‐seropositive PEs. All of these countries detected influenza A(H5) viruses (a total of 27 PEs), but influenza A(H7) viruses were only identified in Spain and France (a total of 4 PEs) (Figure 5). Only one positive PE was reported among the three RCs that as a group accounted for more than 60% of all PEs sampled.

Figure 6

Sampling density, expressed as the number of PEs sampled per 100 km2 (upper map), and geographical distribution of A(H5/H7)‐seropositive PEs (lower map) by administrative unit. Non‐reporting countries are shown in white

Serological test results by administrative unit

Surveillance activities in poultry were reported for 30 NUTS2 (Nomenclature of Territorial Units for Statistics, level 2) and 750 NUTS3 units in 2021. Reporting at NUTS2 level was linked to surveillance activities in Belgium, Germany, Italy and the United Kingdom (Northern Ireland). Out of the 24,290 PEs sampled, 5,924 and 18,366 were reported at NUTS2 and NUTS3 levels, respectively. Out of the 31 seropositive PEs, 4 and 27 were reported at NUTS2 and NUTS3 levels, respectively. Figure 6 shows the geographical distribution of surveillance activities and the numbers of A(H5/H7)‐seropositive PEs in 2021. Data are presented at the NUTS level of reporting (i.e. maps show a combination of NUTS2 and NUTS3 units). The sampling density, estimated as the number of PEs sampled per 100 km2 within a NUTS region, and distribution of A(H5/H7)‐seropositive PEs are presented in Figure 6 in the upper and lower maps, respectively.

Serological test results by month

Since 2019, data on poultry surveillance have been reported on a monthly basis. The distribution of PEs testing positive for influenza A(H5/H7) viruses by month shows that the months with the largest proportions and highest numbers of A(H5/H7)‐seropositive PEs were May and December 2021 (Figure 7). During these months, 6 and 4 PEs, respectively, were reported seropositive, compared to a number of 1 to 4 PEs during other months of the year. However, these differences do not appear to be significant. There was no apparent correlation between higher seropositivity rates and higher numbers of PEs sampled. However, as noted in the previous report, the month with the highest number of seropositive PEs corresponded to the month during which most of the PEs from the poultry category ‘game birds (waterfowl)’ were sampled. In 2020, this was the case in June, while in 2021, it occurred in May (Figure 10): 56 PEs were sampled in May compared to 83 during the other 11 months. Out of 11 seropositive PEs in waterfowl game birds, 5 were identified in May.

Figure 7

(A) Total number of PEs sampled by month with values above bars referring to the number of PEs sampled. (B) percentage (y‐axis) and number (above bars) of PEs sampled that tested seropositive for influenza A(H5/H7) viruses by month

Figure 10

Monthly number of PEs sampled and seropositive for influenza A(H5/H7) viruses in 2021, presented by poultry category. The scale of the vertical axes is specific to each category. Some positive test results (e.g. in conventional laying hens) are not visible due to the low number of positive PEs during the respective months (e.g. 1 A(H5)‐positive PE only). The asterisks indicate whether there was at least one positive PE reported for the respective category and month

For the 10 countries reporting A(H5/H7)‐seropositive PEs, the distribution of these sampling events by month is shown in Figure 3.8 (Figure 8).

Figure 8

Monthly numbers of PEs sampled and seropositive for influenza A(H5/H7) viruses in 2021, presented for RCs with at least one A(H5/H7)‐seropositive PE only. The scale of the vertical axes is specific to each country

Serological test results by poultry category

The highest numbers of PEs sampled by RCs in 2021 were from the backyard and conventional laying hen categories (n = 4,683 and 3,435, respectively) (Figure 9A). These most frequently sampled categories were the same as in previous years. Other categories sampled in high numbers were free‐range laying hens, breeding chickens, growers and fattening turkeys (Figure 9B).

In 2021, as in 2020 and earlier, the highest percentage of A(H5/H7)‐seropositive PEs was found in the waterfowl game bird category (7.9% out of 139 waterfowl game bird PEs sampled), followed by breeding geese (3.5% out of 142 PEs) and breeding ducks (2.8% out of 212 PEs). Proportions of seropositive PEs were below 1% for all other poultry categories. The fattening duck category had a lower proportion of seropositive PEs compared to the previous year (0.1% out of 940 PEs sampled). When considering only gallinaceous species, the highest percentage of A(H5/H7)‐seropositive PEs was observed in the backyard flocks category (0.1% out of 4,683 PEs sampled). No A(H5/H7)‐positive test results were found in breeding chickens, broilers (heightened risk), turkeys (fattening or breeding), growers and Muscovy ducks. One positive PE was found in the conventional laying hen category, unlike in 2020 when no positive PE had been reported for this poultry category.

In addition to A(H5/H7)‐positive test results, 14 RCs reported positive test results for non‐A(H5/H7) subtype AIVs8 in poultry (Austria, Belgium, Czechia, Estonia, France, Germany, Iceland, Latvia, Luxembourg, Malta, the Netherlands, Norway, Spain and Sweden). There were 310 PEs seropositive for non‐A(H5/H7) subtype AIVs, to which the free‐range laying hen, breeding chicken, backyard flocks, conventional laying hen and fattening duck categories contributed the most. Proportions of PEs seropositive for non‐A(H5/H7) subtype AIVs by poultry category may not be reliably estimated, as reporting of these subtypes is non‐mandatory. Therefore, results for non‐A(H5/H7) subtype AIVs are excluded from Figure 9.

For each poultry category, detailed results by month are shown in Figure 10. In addition, surveillance results by species and order are shown in Figure B.1 in Appendix B. The figure shows that, regardless of the management system, seropositive PEs were found in Anseriformes (domestic and mallard ducks as well as geese and other Anseriformes), chickens and ratites. A large number of seropositive samples were identified in PEs raising game birds from the order Anseriformes, for which the bird species was not available.

Figure B.1

(A) Number of PEs sampled by poultry species, (B) proportion of PEs sampled that tested positive for influenza A(H5/H7) viruses by serology. The numbers above bars indicate the numbers of seropositive PEs. Bars are colour‐coded to identify the order to which species belong to. Species names were not reported for some PEs, for which only the wild bird order was identified. Ostriches, emus and other ratites were classified under the term ‘ratites’ (no order), given that species names were not always available

Serological test results: summary

Figure 11 shows only RCs and poultry categories in which A(H5/H7)‐seropositive PEs were detected in case there was at least one PCR‐confirmed A(H5/H7)‐positive PE. Spain, France and Poland were the countries reporting the most A(H5)‐seropositive PEs. These PEs belonged mainly to waterfowl game birds in Spain, breeding ducks in France and breeding geese in Poland. Spain and France also reported the detection of A(H7)‐seropositive PEs (waterfowl game birds and breeding ducks, respectively).

Figure 11

Number of PEs seropositive for influenza A(H5/H7) viruses by RC and poultry category in 2021, presented only for RCs and poultry categories with at least one PCR‐confirmed A(H5/H7)‐positive PE

The sensitivity of serological surveillance activities to detect HPAIVs in RCs depends on several parameters, including the size of the poultry population, the number of distinct PEs sampled, the sensitivity of within‐establishment sampling and the design prevalence (proportion of distinct PEs which is expected to be infected should HPAI be present in the country).

PCR and virological test results

Out of the 31 PEs with positive serological tests for influenza A(H5/H7) viruses, samples from 24 PEs were further tested for AIV viral RNA using PCR, which resulted in 5 of these PEs testing also positive by PCR:

2 positive PEs for non‐A(H5/H7) subtype LPAIVs in breeding ducks in France.

1 positive PE for the HPAI A(H5) subtype in waterfowl game birds in Denmark.

1 positive PE for the LPAI A(H5) subtype in breeding geese in Czechia.

1 PE for influenza A(H5) virus (virus pathogenicity unknown) in the ‘other’ poultry category in Bulgaria.

Most of the seropositive PEs were tested by PCR on the same day (n = 16), while the remainder were re‐sampled for PCR testing on average 12 days after the serological tests. No virus isolation (VI) results were available for the PEs with positive serological or PCR tests. VI results were available for samples from 1 PE in Belgium and were positive for non‐A(H5/H7) subtype LPAIVs.

In addition, 16 countries also reported PCR results from 1,858 PEs which did not correspond to the follow‐up testing of a positive serology event (e.g. in some PEs, PCR tests were used for screening). Sixty‐five of these PEs were found positive for AIVs. These PCR‐positive PEs were located in Belgium, Bulgaria, Estonia, Germany, Italy, Lithuania, Luxembourg, Norway, Slovakia and Romania. Among these, only 16 PEs were PCR‐positive for HPAI A(H5) viruses and were located in Bulgaria, Estonia, Germany and Norway.

Wild birds

Number of wild birds sampled

In 2021, a total of 31,382 wild birds were sampled by 27 MSs, Iceland, Norway, Switzerland and the United Kingdom (Northern Ireland) (31 RCs) either by active or passive surveillance.

In addition to the sampling carried out under European funding (‘EU co‐funded passive surveillance’ in blue in Figure 12), 5 MSs reported surveillance results from their national programmes (non‐EU co‐funded programmes) (Belgium, Estonia, Germany, Poland and Spain). It must be highlighted that MSs are not obliged to report surveillance results from surveillance activities other than the EU co‐funded passive surveillance. Norway, Switzerland and Iceland reported results from their national programmes.

Figure 12

Number of wild birds sampled by RCs in 2021 according to the type of surveillance programme

For the purpose of this report, wild birds ‘found dead’ or ‘live with clinical signs’ were classified under passive surveillance (the latter including injured wild birds), while wild birds reported as ‘hunted with clinical signs’, ‘hunted without clinical signs’ and ‘live without clinical signs’ were considered as wild birds sampled by active surveillance. This is consistent with the classification method followed in previous reports. Active surveillance is assumed to be undertaken by voluntary contributors, as MSs are not obliged to report results from active surveillance in wild birds.

All 31 RCs reported results from their passive surveillance programmes in 2021. Of the total number of wild birds sampled, 20,920 were sampled by passive surveillance, which is more than in the past 3 years (e.g. n = 12,418 in 2020) (Table 1). The sensitivity of passive surveillance for AI in wild birds is highly dependent on the probability of contributors discovering and reporting wild birds found dead, injured or with clinical signs.

Table 1

Number of wild birds sampled by RCs in 2021 (light grey background), with active and passive surveillance presented separately and combined as a total, and the number of wild birds sampled by passive surveillance from 2018 to 2021 (no background colour). In case of low numbers or no data reported for active surveillance, the respective RC may have reported only little data to EFSA or not carried out active surveillance at all

Reporting country	Passive surveillance				Active surveillance (2021)	Total (2021)
	2018	2019	2020	2021
Austria	109	85	183	419	0	419
Belgium	237	423	275	290	448	738
Bulgaria	58	65	70	103	13	116
Croatia	223	160	92	110	0	110
Cyprus	109	87	137	129	7	136
Czechia	94	104	127	208	0	208
Denmark	148	111	288	760	0	760
Estonia	16	8	3	307	12	319
Finland	195	174	222	560	0	560
France	113	158	503	875	0	875
Germany	1,711	1,392	3,041	7,321	7,844	15,165
Greece	13	12	6	26	4	30
Hungary	371	338	472	228	0	228
Iceland	–	2	9	18	0	18
Ireland	142	78	165	265	0	265
Italy	2,109	2,719	2,791	4,005	0	4,005
Latvia	14	15	4	151	0	151
Lithuania	70	63	139	234	0	234
Luxembourg	–	50	135	305	0	305
Malta	–	–	9	9	42	51
Netherlands	663	643	878	1,149	0	1,149
Norway	–	28	128	348	800	1,148
Poland	36	33	97	649	777	1,426
Portugal	82	126	74	64	0	64
Romania	244	201	107	213	19	232
Slovakia	84	45	83	82	0	82
Slovenia	178	231	270	323	0	323
Spain	344	281	437	732	490	1,222
Sweden	455	456	410	803	0	803
Switzerland	45	30	55	162	6	168
United Kingdom	1,282	816	1,208	–	–	–
United Kingdom (Northern Ireland)	–	–	–	72	0	72
Total	9,145	8,934	12,418	20,920	10,462	31,382

Some RCs (n = 12) also performed and reported results from active surveillance (non‐EU co‐funded programmes for which reporting is non‐mandatory), particularly, Belgium, Germany, Malta, Norway and Poland, which sampled a higher number of wild birds by active than passive surveillance (Table 1). Although active surveillance was carried out in other countries as well, the data shown in this report represent only the data that were submitted to EFSA. As reporting of results from active surveillance in wild birds to EFSA is non‐mandatory, the numbers reported below do not represent the full extent of active surveillance activities conducted by some of the countries. Consequently, this report contains complete data for passive surveillance only and focuses mainly on summarising the sampling activities and results obtained by passive surveillance.

Timing of sampling in wild birds

In Figure 13, the quarterly distribution of the number of wild birds sampled by passive surveillance in 2021 is shown by RC. The highest numbers of samples were taken during the first quarter (January–March). The distribution of sampling was lower but relatively consistent during the following three quarters:

Figure 13

Quarterly percentage (bars) and total numbers (values) of wild birds sampled by passive surveillance by RCs in 2021, with the first quarter starting in January 2021

quarter 1: 9,055 wild birds (43%);

quarter 2: 4,678 wild birds (22%);

quarter 3: 3,395 wild birds (16%);

quarter 4: 3,792 wild birds (18%).

Figure 13 highlights variation among RCs in terms of the sampling distribution throughout the year (percentage of samples taken during each quarter by each RC). However, sampling was most intensive (over 25%) in the first quarter for most countries except Croatia, Finland, Italy, Malta, Portugal and Romania.

Species distribution in wild birds

Among wild birds sampled by passive surveillance, there were:

16,615 wild birds fully identified at species level. These samples belonged to a total of 294 wild bird species belonging to 25 orders.

3,683 wild birds for which only the genus was identified but not the species (14 orders).

271 wild birds for which only the family was identified but not the species (13 orders).

64 wild birds for which only the order was identified (7 orders).

287 wild birds for which species identification information was completely missing. Wild birds in this category are shown as ‘Species unknown’ in Figure 14.

Figure 14

Total number of wild birds of the different orders, sampled by passive surveillance in 2021 (n = 20,920). The y‐axis is presented on a non‐linear scale to improve visibility

The most frequently sampled order were Anseriformes (n = 6,302), which accounted for 30.1% of the total number of wild birds sampled by passive surveillance. The orders Passeriformes, Accipitriformes, Charadriiformes, Columbiformes, Pelecaniformes and Strigiformes were also sampled in high numbers (n > 1,000 each) (Figure 14).

Also most active surveillance samples were taken from wild birds of the order Anseriformes. A total of 7,136 samples from this order were tested by active surveillance, out of a total of 10,462 samples tested (68.2%). The distribution of wild birds sampled by order is shown for active and passive surveillance combined in Figure C.1 in Appendix C.

Figure C.1

Total numbers of wild birds of the different orders sampled by passive and active surveillance by RCs in 2021. The group ‘NA’ includes all wild birds for which data on species and order were not available. The y‐axis is presented on a non‐linear scale to improve visibility

The majority (approximately 60%) of the species sampled by passive surveillance belonged to the orders Passeriformes (n = 72), Anseriformes (n = 43), Charadriiformes (n = 42) and Accipitriformes (n = 29). In Figure 15, the 40 species (out of 294 fully identified species) with the most sampled wild birds in 2021 are shown.

Figure 15

Total numbers of wild birds sampled for the 40 most sampled wild bird species reported by passive surveillance in 2021 (13,302 wild birds out of 16,615 fully identified wild birds). The bar colours refer to the bird orders. The asterisks indicate the wild bird species belonging to the 50 target species recommended by EFSA for HPAI surveillance. English common names for the species shown are provided in Table D.1 in Appendix D

The 3 most sampled species by passive surveillance were the mute swan (Cygnus olor), the common buzzard (Buteo buteo) and the mallard duck (Anas platyrhynchos), consistent with the 2020 results, albeit in a different order. The fourth most sampled species in 2020 was the common pigeon (Columba livia), which was not among the top 10 most sampled species in 2021. All English common names for the species shown in Figure 15 are listed in Table D.1 in Appendix D.

Table D.1

English common names and scientific names of wild bird species sampled in 2021

Scientific name	English common name
Acanthis flammea	Redpoll
Accipiter gentilis	Northern goshawk
Accipiter nisus	Eurasian sparrowhawk
Acrocephalus arundinaceus	Great reed‐warbler
Actitis hypoleucos	Common sandpiper
Aegithalos caudatus	Long‐tailed tit
Aegolius funereus	Boreal owl
Aegypius monachus	Cinereous vulture
Aix galericulata	Mandarin duck
Aix sponsa	Wood duck
Alauda arvensis	Eurasian skylark
Alca torda	Razorbill
Alcedo atthis	Common kingfisher
Alectoris chukar	Chukar
Alectoris graeca	Rock partridge
Alectoris rufa	Red‐legged partridge
Alle alle	Little auk
Alopochen aegyptiaca	Egyptian goose
Amazona leucocephala	Cuban parrot
Amazona oratrix	Yellow‐headed amazon
Anas acuta	Northern pintail
Anas crecca	Common teal
Anas platyrhynchos	Mallard
Anser albifrons	Greater white‐fronted goose
Anser anser	Greylag goose
Anser brachyrhynchus	Pink‐footed goose
Anser cygnoides	Swan goose
Anser erythropus	Lesser white‐fronted goose
Anser fabalis	Bean goose
Anthus pratensis	Meadow pipit
Anthus trivialis	Tree pipit
Apus apus	Common swift
Apus pallidus	Pallid swift
Aquila adalberti	Spanish imperial eagle
Aquila chrysaetos	Golden eagle
Aquila fasciata	Bonelli's eagle
Aquila heliaca	Eastern imperial eagle
Ardea alba	Great white egret
Ardea cinerea	Grey heron
Ardea purpurea	Purple heron
Arenaria interpres	Ruddy turnstone
Asio flammeus	Short‐eared owl
Asio otus	Northern long‐eared owl
Athene noctua	Little owl
Aythya ferina	Common pochard
Aythya fuligula	Tufted duck
Aythya marila	Greater scaup
Aythya nyroca	Ferruginous duck
Bombycilla garrulus	Bohemian waxwing
Bonasa bonasia	Hazel grouse
Botaurus lentiginosus	American bittern
Botaurus stellaris	Eurasian bittern
Branta bernicla	Brent goose
Branta canadensis	Canada goose
Branta leucopsis	Barnacle goose
Branta ruficollis	Red‐breasted goose
Bubo bubo	Eurasian eagle‐owl
Bubo scandiacus	Snowy owl
Bubulcus ibis	Cattle egret
Bucephala clangula	Common goldeneye
Burhinus oedicnemus	Eurasian thick‐knee
Buteo buteo	Eurasian buzzard
Buteo lagopus	Rough‐legged buzzard
Buteo rufinus	Long‐legged buzzard
Butorides striata	Green‐backed heron
Cairina moschata	Muscovy duck
Calidris alba	Sanderling
Calidris alpina	Dunlin
Calidris canutus	Red knot
Calidris ferruginea	Curlew sandpiper
Calidris minuta	Little stint
Calidris pugnax	Ruff
Calonectris diomedea	Scopoli's shearwater
Caprimulgus europaeus	European nightjar
Carduelis carduelis	European goldfinch
Cepphus grylle	Black guillemot
Charadrius alexandrinus	Kentish plover
Charadrius dubius	Little ringed plover
Charadrius hiaticula	Common ringed plover
Chlidonias niger	Black tern
Chloris chloris	European greenfinch
Ciconia ciconia	White stork
Ciconia nigra	Black stork
Circaetus gallicus	Short‐toed snake‐eagle
Circus aeruginosus	Western marsh‐harrier
Circus cyaneus	Hen harrier
Circus pygargus	Montagu's harrier
Cisticola juncidis	Zitting cisticola
Clanga pomarina	Lesser spotted eagle
Clangula hyemalis	Long‐tailed duck
Coccothraustes coccothraustes	Hawfinch
Columba livia	Rock dove
Columba oenas	Stock dove
Columba palumbus	Common woodpigeon
Copsychus malabaricus	White‐rumped shama
Coracias garrulus	European roller
Corvus corax	Common raven
Corvus corone	Carrion crow
Corvus frugilegus	Rook
Corvus monedula	Eurasian jackdaw
Coturnix coturnix	Common quail
Crex crex	Corncrake
Cuculus canorus	Common cuckoo
Cyanecula svecica	Bluethroat
Cyanistes caeruleus	Eurasian blue tit
Cyanocorax yncas	Inca jay
Cyanopica cooki	Iberian azure‐winged magpie
Cygnus atratus	Black swan
Cygnus columbianus	Tundra swan
Cygnus cygnus	Whooper swan
Cygnus olor	Mute swan
Delichon urbicum	Northern house martin
Dendrocopos leucotos	White‐backed woodpecker
Dendrocopos major	Great spotted woodpecker
Dryobates minor	Lesser spotted woodpecker
Dryocopus martius	Black woodpecker
Egretta garzetta	Little egret
Elanus caeruleus	Black‐winged kite
Emberiza cirlus	Cirl bunting
Emberiza citrinella	Yellowhammer
Erithacus rubecula	European robin
Eudocimus ruber	Scarlet ibis
Eudromias morinellus	Eurasian fotterel
Falco columbarius	Merlin
Falco eleonorae	Eleonora's falcon
Falco naumanni	Lesser kestrel
Falco peregrinus	Peregrine falcon
Falco rusticolus	Gyrfalcon
Falco subbuteo	Eurasian hobby
Falco tinnunculus	Common kestrel
Ficedula hypoleuca	European pied flycatcher
Francolinus francolinus	Black francolin
Fratercula arctica	Atlantic puffin
Fringilla coelebs	Common chaffinch
Fringilla montifringilla	Brambling
Fulica atra	Common coot
Fulica cristata	Red‐knobbed coot
Fulmarus glacialis	Northern fulmar
Gallinago gallinago	Common snipe
Gallinula chloropus	Common moorhen
Gallus gallus	Chicken
Garrulus glandarius	Eurasian jay
Gavia arctica	Arctic loon
Gavia stellata	Red‐throated loon
Geronticus eremita	Northern bald ibis
Glaucidium passerinum	Eurasian pygmy‐owl
Grus grus	Common crane
Grus virgo	Demoiselle crane
Guira guira	Guira cuckoo
Gypaetus barbatus	Bearded vulture
Gyps fulvus	Griffon vulture
Gyps himalayensis	Himalayan vulture
Gyps rueppelli	Rüppell's vulture
Haematopus ostralegus	Eurasian oystercatcher
Haliaeetus albicilla	White‐tailed sea‐eagle
Hieraaetus pennatus	Booted eagle
Himantopus himantopus	Black‐winged stilt
Hirundo rustica	Barn swallow
Hydrobates pelagicus	European storm‐petrel
Hydrocoloeus minutus	Little gull
Ixobrychus minutus	Common little bittern
Lagopus lagopus	Willow grouse
Lanius collurio	Red‐backed shrike
Lanius excubitor	Great grey shrike
Lanius minor	Lesser grey shrike
Larus argentatus	European herring gull
Larus cachinnans	Caspian gull
Larus canus	Mew gull
Larus fuscus	Lesser black‐backed gull
Larus marinus	Great black‐backed gull
Larus melanocephalus	Mediterranean gull
Larus michahellis	Yellow‐legged gull
Larus ridibundus	Black‐headed gull
Leiopicus medius	Middle spotted woodpecker
Limosa lapponica	Bar‐tailed godwit
Locustella naevia	Common grasshopper‐warbler
Lophura leucomelanos	Kalij pheasant
Loxia curvirostra	Red crossbill
Lyrurus tetrix	Black grouse
Mareca penelope	Eurasian wigeon
Mareca strepera	Gadwall
Marmaronetta angustirostris	Marbled teal
Melanitta fusca	Velvet scoter
Melanitta nigra	Common scoter
Melanocorypha calandra	Calandra lark
Mergellus albellus	Smew
Mergus merganser	Goosander
Mergus serrator	Red‐breasted merganser
Merops apiaster	European bee‐eater
Microcarbo niger	Little cormorant
Microcarbo pygmaeus	Pygmy cormorant
Milvus migrans	Black kite
Milvus milvus	Red kite
Morus bassanus	Northern gannet
Morus capensis	Cape gannet
Motacilla alba	White wagtail
Muscicapa striata	Spotted flycatcher
Myiopsitta monachus	Monk parakeet
Neophron percnopterus	Egyptian vulture
Netta rufina	Red‐crested pochard
Nucifraga caryocatactes	Northern nutcracker
Numenius arquata	Eurasian curlew
Numenius phaeopus	Whimbrel
Nycticorax nycticorax	Black‐crowned night‐heron
Oenanthe oenanthe	Northern wheatear
Oriolus oriolus	Eurasian golden oriole
Otis tarda	Great bustard
Otus scops	Eurasian scops‐owl
Oxyura leucocephala	White‐headed duck
Pandion haliaetus	Osprey
Parus major	Great tit
Passer domesticus	House sparrow
Passer montanus	Eurasian tree sparrow
Pavo cristatus	Peafowl
Pelecanus crispus	Dalmatian pelican
Pelecanus onocrotalus	Great white pelican
Perdicinae	Partridge
Perdix perdix	Grey partridge
Pernis apivorus	European honey‐buzzard
Pernis ptilorhynchus	Oriental honey‐buzzard
Phalacrocorax aristotelis	European shag
Phalacrocorax carbo	Great cormorant
Phasianus colchicus	Common pheasant
Phasianus versicolor	Green pheasant
Phoenicopterus roseus	Greater flamingo
Phoenicopterus ruber	American flamingo
Phoenicurus ochruros	Black redstart
Phoenicurus phoenicurus	Common redstart
Phylloscopus collybita	Common chiffchaff
Phylloscopus sibilatrix	Wood warbler
Pica pica	Eurasian magpie
Picus canus	Grey‐faced woodpecker
Picus viridis	Eurasian green woodpecker
Platalea leucorodia	Eurasian spoonbill
Plegadis falcinellus	Glossy ibis
Podiceps cristatus	Great crested grebe
Podiceps nigricollis	Black‐necked grebe
Porphyrio porphyrio	Purple swamphen
Porzana porzana	Spotted crake
Prunella modularis	Dunnock
Psittacula krameri	Rose‐ringed parakeet
Psittacus erithacus	Grey parrot
Ptyonoprogne rupestris	Eurasian crag martin
Puffinus puffinus	Manx shearwater
Puffinus yelkouan	Yelkouan shearwater
Pyrrhocorax pyrrhocorax	Red‐billed chough
Pyrrhula pyrrhula	Eurasian bullfinch
Rallus aquaticus	Western water rail
Recurvirostra avosetta	Pied avocet
Regulus ignicapilla	Common firecrest
Regulus regulus	Goldcrest
Rissa tridactyla	Black‐legged kittiwake
Saxicola torquatus	Common stonechat
Scolopax rusticola	Eurasian woodcock
Serinus serinus	European serin
Sitta europaea	Eurasian nuthatch
Somateria mollissima	Common eider
Spatula clypeata	Northern shoveler
Spatula querquedula	Garganey
Spinus spinus	Eurasian siskin
Sterna hirundo	Common tern
Sterna paradisaea	Arctic tern
Streptopelia decaocto	Eurasian collared‐dove
Streptopelia turtur	European turtle‐dove
Strix aluco	Tawny owl
Strix nebulosa	Great grey owl
Strix uralensis	Ural owl
Struthio camelus	Ostrich
Sturnus unicolor	Spotless starling
Sturnus vulgaris	Common starling
Surnia ulula	Northern hawk‐owl
Sylvia atricapilla	Eurasian blackcap
Sylvia borin	Garden warbler
Sylvia communis	Common whitethroat
Sylvia curruca	Lesser whitethroat
Sylvia melanocephala	Sardinian warbler
Tachybaptus ruficollis	Little grebe
Tachymarptis melba	Alpine swift
Tadorna ferruginea	Ruddy shelduck
Tadorna tadorna	Common shelduck
Tetrao urogallus	Western capercaillie
Threskiornis aethiopicus	African sacred ibis
Tringa glareola	Wood sandpiper
Tringa totanus	Common redshank
Troglodytes troglodytes	Northern wren
Turdus iliacus	Redwing
Turdus merula	Eurasian blackbird
Turdus philomelos	Song thrush
Turdus pilaris	Fieldfare
Turdus viscivorus	Mistle thrush
Tyto alba	Common barn‐owl
Upupa epops	Common hoopoe
Uria aalge	Common guillemot
Vanellus vanellus	Northern lapwing

Forty‐seven out of the 50 target species recommended by EFSA for HPAI surveillance are included in the 294 species reported (Table E.1 in Appendix E). A total of 41.3% and 34.7% of the wild birds sampled by passive and active surveillance belonged to these target species, respectively (n = 8,648 and 3,634, respectively).

Avian influenza in wild birds

Detection of avian influenza viruses in samples

When analysing data from both active and passive surveillance, a total of 3,098 (9.9%) wild birds, out of the 31,382 sampled by RCs, tested positive for AIVs (Table 2). This proportion was slightly higher than in 2020 (8,6%) and twice as high as in 2019 (4.7%). Of the 3,098 AIV‐positive wild birds, 2,314 were infected with HPAIVs and 784 with LPAIVs.9

Table 2

Test results for wild birds sampled by passive (no background colour) and active (light grey background) surveillance by RCs in 2021, presented by wild bird status. All VI‐positive wild birds (column ‘Positive by VI’) had previously tested positive by PCR

	Wild bird status	No. of wild birds sampled	No. of AIV‐positive wild birds
			Positive by PCR or VI	Positive by VI	HPAIV‐positive	LPAIV‐positive
Active	Hunted with clinical signs	94	18	0	15	3
	Hunted without clinical signs	2,186	181	0	39	142
	Live without clinical signs	8,182	198	12	40	158
	Subtotal	10,462	397	12	94	303
Passive	Found dead	20,095	2,616	42	2,144	472
	Live with clinical signs	825	85	0	76	9
	Subtotal	20,920	2,701	42	2,220	481
Total		31,382	3,098	54	2,314	784

In 2021, the majority of AIV‐positive wild birds were found by passive surveillance (87%), as in 2020 but different from 2019 (i.e. in 2019, 7% of AIV infections were detected by passive surveillance). Most AIV‐positive wild birds were found dead (n = 2,616, including 2,144 HPAIV‐positive wild birds). The proportions of HPAIV‐positive wild birds in active and passive surveillance were 1% and 11%, respectively, indicating a higher mortality involved.

Wild bird sampling was reported for 21 NUTS2 units, 220 NUTS3 units and 19,476 individual coordinate locations in 2021. Italy reported surveillance results at NUTS2 level, while Czechia, Hungary, Ireland, Lithuania, Malta, Poland, Romania and Spain reported results at NUTS3 level. Latvia, Luxembourg and the Netherlands reported some results at NUTS3 level and some for individual location coordinates. Other countries reported results with location coordinates only.

Out of the 31,382 wild birds sampled, 4,005 and 4,609 were reported at NUTS2 and NUTS3 levels, respectively, while 22,768 were reported for individual location coordinates. Out of the 2,314 HPAIV‐positive (A(H5/H7) subtypes) wild birds, 21 and 401 were reported at NUTS2 and NUTS3 levels, respectively, while 1,892 were reported for individual location coordinates.

Figure 16 shows the geographical distribution of surveillance activities in wild birds conducted by RCs in 2021. Data are presented at the NUTS level of reporting (i.e. maps show a combination of NUTS2 and NUTS3 units). Data reported with location coordinates were aggregated at NUTS3 level.

Figure 16

Sampling density, expressed as the numbers of wild birds sampled per 100 km2 (upper map), and geographical distribution of all AIV‐ (middle map) and HPAIV‐positive (lower map) wild birds by administrative unit. Non‐reporting countries are shown in white

Larger numbers of AIV‐ and HPAIV‐positive samples coincided with larger sampling densities (Figure 16).

Highly pathogenic avian influenza in wild birds

Highly pathogenic avian influenza results by neuraminidase type

A total of 2,314 wild birds in 22 RCs tested positive for HPAIVs in 2021, more than in 2020 (n = 878) and 2019 (n = 1). All of these HPAIVs were classified as belonging to the A(H5) subtype, and around half of them were identified as influenza A(H5N8) virus (57%). Figure 17 summarises the N subtypes identified for these samples.

Figure 17

AIV neuraminidase (N) subtypes identified for HPAIV‐positive wild birds (all HPAIVs were classified as belonging to the A(H5) subtype). Values are provided above bars. There were no wild birds with more than one N subtype identified

Highly pathogenic avian influenza results by species

A total of 83 species, wild birds from 14 genera of unknown species, wild birds from 5 families of unknown species and 89 wild birds without species identification (no order, family, genus or species identified) were positive for HPAIVs. These HPAIV‐infected wild birds belonged to at least 13 orders, as shown in Figures 18 and 19. These two figures show data from passive and active surveillance combined. The same data are presented separately by type of surveillance in Appendices G and H: Figures G.1 and G.2 (passive surveillance), and Figures H.1 and H.2 (active surveillance).

Figure 18

Number of HPAIV‐positive wild birds detected by both passive and active surveillance, for species with at least one HPAIV‐positive sample. The numbers of wild birds tested are indicated in brackets. Bars are ordered by increasing number of positive wild birds and colour‐coded to identify the order to which species belong to. English common names are provided in Table D.1 in Appendix D.

Figure 19

Proportion of HPAIV‐positive wild birds detected among wild birds tested by both passive and active surveillance, for species with at least one HPAIV‐positive sample. The numbers of wild birds tested are indicated in brackets. Bars are ordered by increasing proportion of positive wild birds and colour‐coded to identify the order to which species belong to. English common names are provided in Table D.1 in Appendix D

Figure G.1

Number of HPAIV‐positive wild birds detected by passive surveillance, for species with at least one HPAIV‐positive sample. The number of wild birds tested is indicated in brackets. Bars are ordered by increasing number of positive wild birds and colour‐coded to identify the order to which species belong to

Figure G.2

Proportion of HPAIV‐positive wild birds detected among wild birds tested by passive surveillance, for species with at least one HPAIV‐positive sample. The number of wild birds tested is indicated in brackets. Bars are ordered by increasing proportion of positive wild birds and colour‐coded to identify the order to which species belong to

Figure H.1

Number of HPAIV‐positive wild birds detected by active surveillance, for species with at least one HPAIV‐positive sample. The number of wild birds tested is indicated in brackets. Bars are ordered by increasing number of positive wild birds and colour‐coded to identify the order to which species belong to

Figure H.2

Proportion of HPAIV‐positive wild birds detected among wild birds tested by active surveillance, for species with at least one HPAIV‐positive sample. The number of wild birds tested is indicated in brackets. Bars are ordered by increasing proportion of positive wild birds and colour‐coded to identify the order to which species belong to

Half of the HPAIV‐positive wild birds belonged to the target species recommended by EFSA for HPAI surveillance (n = 1,227, 53%) (Table E.1 in Appendix E). In particular, the species with the highest number of HPAIV‐positive samples identified was the mute swan (Cygnus olor, n = 432) (Figure 18). The two following species with the highest numbers of HPAIV‐infected wild birds were the barnacle goose (Branta leucopsis, n = 325), which is not listed as a target species, and the common buzzard (Buteo buteo, n = 141). However, a large number of positive wild birds were identified only at the genus level (Cygnus spp., n = 204, and Anser sp., n = 175).

The percentage of HPAIV‐positive wild birds by species shown in Figure 19 should be interpreted with caution, as the number of wild birds sampled for a given species may be very low. For example, only one wild bird identified at the family level Threskiornithidae was sampled and tested positive, yielding a percentage of 100% for this respective family.

Highly pathogenic avian influenza results by type of surveillance

Table 3 shows the proportion of HPAIV‐positive wild birds by type of surveillance. The highest percentages of HPAIV‐positive wild birds by passive surveillance were found in Denmark (38.3% of samples), Latvia (32.5%), Greece (30.8%) and Poland (29.1%).

Table 3

Total numbers of wild birds sampled and positive for HPAIVs by passive and active surveillance in RCs. Cells with grey background indicate that no HPAIV‐positive wild birds were detected in the respective RC by the respective surveillance activity

Country	Passive surveillance		Active surveillance
	No. of wild birds	No. of HPAIV‐positive wild birds (%)	No. of wild birds	No. of HPAIV‐positive wild birds (%)
Austria	419	44 (10.5%)	0	–
Belgium	290	24 (8.3%)	448	2 (0.4%)
Bulgaria	103	2 (1.9%)	13	0 (0%)
Croatia	110	19 (17.3%)	0	–
Cyprus	129	0 (0%)	7	0 (0%)
Czechia	208	0 (0%)	0	–
Denmark	760	291 (38.3%)	0	–
Estonia	307	52 (16.9%)	12	1 (8.3%)
Finland	560	94 (16.8%)	0	–
France	875	49 (5.6%)	0	–
Germany	7,321	916 (12.5%)	7,844	88 (1.1%)
Greece	26	8 (30.8%)	4	0 (0%)
Hungary	228	11 (4.8%)	0	–
Iceland	18	0 (0%)	0	–
Ireland	265	72 (27.2%)	0	–
Italy	4,005	21 (0.5%)	0	–
Latvia	151	49 (32.5%)	0	–
Lithuania	234	0 (0%)	0	–
Luxembourg	305	0 (0%)	0	–
Malta	9	0 (0%)	42	0 (0%)
Netherlands	1,149	169 (14.7%)	0	–
Norway	348	37 (10.6%)	800	3 (0.4%)
Poland	649	189 (29.1%)	777	0 (0%)
Portugal	64	0 (0%)	0	–
Romania	213	0 (0%)	19	0 (0%)
Slovakia	82	0 (0%)	0	–
Slovenia	323	11 (3.4%)	0	–
Spain	732	10 (1.4%)	490	0 (0%)
Sweden	803	139 (17.3%)	0	–
Switzerland	162	2 (1.2%)	6	0 (0%)
United Kingdom (Northern Ireland)	72	11 (15.3%)	0	–

Highly pathogenic avian influenza results by time

Figure 20 displays the timeline of HPAIV detections in wild birds in RCs in 2021, for passive and active surveillance separately (blue and red colours, respectively). As part of the continuing HPAI A(H5Nx) epidemic since late 2020, HPAIVs were detected from the first week of 2021. A second wave of HPAIV incursions was detected around week 40, with the highest proportion of HPAIV‐positive wild birds in week 45. During this week, 27% of samples (passive and active surveillance combined) tested positive for HPAIVs. The highest proportion of HPAIV‐positive wild birds during the first quarter was detected in week 9 (22%), which is in line with the increased sampling effort in the first quarter.

Figure 20

(A) Weekly number of wild birds sampled by both passive and active surveillance, (B) weekly percentage of HPAIV‐positive wild birds found and (C) weekly number of HPAIV‐positive wild birds by taxonomic order

Low pathogenic avian influenza in wild birds

Among the 783 wild birds tested positive for AIVs other than HPAIVs, 107 wild birds were infected with LPAIVs, while no virus pathogenicity results were available for the remaining 676 wild birds. Out of the 676 wild birds for which information on the virus pathogenicity was not available, 247 wild birds were positive for influenza A(H5) and 3 for A(H7) viruses. For the remainder of this section, ‘LPAIV‐positive’ wild birds include all positive wild birds which were not positive for HPAIVs (n = 783). This is consistent with previous reports.

LPAIV‐positive wild birds were reported by 22 RCs. Among these positive wild birds, 293 were classified as influenza A(H5) and 35 as A(H7) viruses. The majority of the LPAIVs detected were reported as non‐A(H5/H7) subtype AIVs (n = 362), without further information on the subtypes provided. Figure 21 summarises all the identified and reported LPAIVs.

Figure 21

AIV haemagglutinin (H) subtypes identified for LPAIV‐positive wild birds. Values are provided above bars. Wild birds for which positive samples could not all be typed (for example, one sample was characterised as belonging to the A(H5) subtype, while for another sample from the same wild bird the H subtype was unknown) are classified under the H subtype that was available (in this example, the A(H5) subtype). There were no wild birds for which more than one H subtype was identified

As shown in Figure 22, most LPAIV‐positive wild birds were found in week 50 (n = 39) for both types of surveillance. However, as for HPAIV‐positive wild birds, two distinct peaks of LPAIV detections can be identified: in the first and last quarters of the year. There were very few LPAIV‐positive wild birds between March and August, except for week 25 for active surveillance. Most LPAIV‐positive wild birds belonged to the order Anseriformes (Figure 22C), which is the most sampled order by both active and passive surveillance.

Figure 22

(A) Weekly number of wild birds sampled by both passive and active surveillance, (B) weekly percentage of LPAIV‐positive wild birds found and (C) weekly number of LPAIV‐positive wild birds by taxonomic order

Abundance and distribution of wild birds in Europe

Voluntary contribution data on abundance and distribution of wild bird species have been made available to EFSA by the EBP. EBP is one of the three major monitoring projects run by the European Bird Census Council (EBCC). This project mobilises year‐round observational data submitted by volunteer birdwatchers to the online wild bird recording portals operating across Europe (ca. 50 million wild bird records from ca. 100,000 voluntary contributors annually). Information on the distribution of the 50 species included in the EFSA target list of wild bird species (Table E.1 in Appendix E) is now being submitted to EFSA annually, aggregated at NUTS3 and monthly level. The data provide two different measures for each NUTS3 region and month:

the total number of all wild birds observed in that specific location during that month.

the number of wild birds for each of the 50 species included in the target list of wild bird species observed in that location during that month.

The total number of wild birds observed is a function of abundance and observation effort. This value may be used as an indirect measure of the effort taking place in a given location. However, it may not be directly interpreted as the observation effort, as this would assume constant abundance across locations.

Figure F.1 (Appendix F) shows the density of all wild birds (upper map) and wild birds of the 50 target species (lower map) observed in a specific location, each estimated as the total number of observations in the NUTS3 region divided by the surface of the area (also available in Zenodo (https://doi.org/10.5281/zenodo.7053170)). This figure shows that the highest densities of observations of wild birds (all species, i.e. an indirect measure of the observation effort) were in Belgium, Denmark, the Netherlands and some regions of Austria, France, Germany, Spain, Sweden, Switzerland and the United Kingdom. The density was lowest in Bulgaria, Croatia, Estonia, Greece, Hungary, Iceland, Ireland, Latvia, Romania and Slovenia. No data were available for Lithuania. Within countries, the variability between NUTS3 regions was high. During the course of the year, wild bird observations were reported at least once for 1,309 NUTS3 regions in total in the countries for which EBP data were available. Wild birds from the EFSA target list were reported in all but 2 of these NUTS3 regions (Figure F.1, lower map).

Figure F.1

Density of wild bird observations for 2021 by NUTS3 region, as per data provided by the EBP project. The density of observations was estimated as the total number of observations in the NUTS3 region divided by the surface of the area. The upper map shows all wild bird species, while the lower map is restricted to species from the EFSA target list

Showing these two types of records, observation effort and density for a given species, provides an indicator of the reliability of the data presented. For example, if a low number of wild birds of the species included in the list of target species is observed for a certain NUTS3 region and month, in an area where the observation effort is high (large number of total observations), our confidence in the reliability of the information would be higher than if the total number of observations was low.

Additional maps are available in Zenodo at the monthly level (https://doi.org/10.5281/zenodo.7053222): these maps display both the number of wild birds from target species observed in each NUTS3 region (EBP data) and the number of wild birds from target species sampled by passive surveillance (RCs data).

Figures F.2 and F.3 (Appendix F) show the distribution of wild bird observations according to the EBP data, by wild bird orders and species for the entire year, for the 50 species included in the EFSA target list (Table E.1 in Appendix E). A total of 46% of the observations reported concerned Anseriformes, followed by Pelecaniformes, Charadriiformes, Accipitriformes and Passeriformes. These distributions could not be compared to the distribution of orders and species sampled for AI surveillance, given that detailed data were only available for the target list species. For example, Columbiformes ranked third in terms of sampling but were not reported in the available EBP data.

Figure F.2

Number of wild birds from the EFSA list of target wild bird species (n = 50) observed in 2021 and recorded in the EBP project, aggregated by wild bird order

Figure F.3

Number of wild birds from the EFSA list of target wild bird species (n = 50) observed in 2021 and recorded in the EBP project, aggregated by wild bird species

Last, there were also some discrepancies between the wild birds reported as observed and found dead by passive surveillance programmes. There were 4,764 records of dead bird samples from EFSA target species for a given species, NUTS3 and month. Among these, 676 were not associated with a corresponding observation in the EBP data. Therefore, it is difficult to use the EBP data to assess the quality of passive surveillance in RCs.

Discussion and conclusions

It is important to note that risk‐based sampling strategies used for AI surveillance may vary between countries. Therefore, the differences in AI incidence between countries observed in this report, both in poultry and wild birds, should be interpreted with caution. Direct comparisons between countries should be avoided.

A targeted (non‐representative) sampling approach helps to increase the efficiency of detection of AIVs but prevents valid assessments of measures of disease, differences between locations, categories or species, or trends over time. Comparisons of seropositivity rates between different locations, categories, species or time periods are valid for the specific observations (surveillance samples) only and cannot be extrapolated to the source populations. Seropositivity rates are not only influenced by disease but also the efficiency of targeting of the risk‐based sampling approach. Therefore, increases in seropositivity rates over time may be due to either changes in the disease situation or improved targeting. Changes in prevalence or incidence may not be fully captured by risk‐based surveillance programmes only, which is why a more representative sampling approach should be followed, using methodologies that have been standardised between RCs, for interpretation and comparison of such numbers.

An increasing trend in the number of PEs sampled was observed between 2017 and 2019 until a plateau of more than 24,000 PEs sampled per year was reached for the last 3 years. Both the number and proportion of PEs seropositive for influenza A(H5/H7) viruses were around half of the ones observed in 2020 with overall only 31 seropositive PEs identified in 2021. The cause of this decrease remains unclear. There may have been either changes in the disease situation or targeting approach. In addition to the small number of seropositive PEs, variations in sampling activities among RCs and between years mean that it was difficult to draw valid inferences from the percentages detected. In 2021, 27 PEs tested positive for influenza A(H5) and 4 for A(H7) viruses, while all HPAIV‐positive detections in wild birds were characterised as HPAI A(H5) viruses. This confirms a more active circulation of influenza A(H5) compared to A(H7) viruses in Europe, consistent with previous years.

The 2 months with slightly higher A(H5/H7) seropositivity rates were May and December 2021, while the latter may have been linked to the large HPAI A(H5Nx) epidemic occurring in Europe since October 2020. This epidemic was associated with 3,700 outbreaks during the epidemic season of 2020–2021, in both poultry and wild birds (EFSA, ECDC and EURL, 2022), and is the largest HPAI A(H5Nx) epidemic recorded in the EU since the 2016–2017 epidemic (EFSA, ECDC and EURL, 2017a). Recent outbreaks in Europe in 2022 appear to be linked to an even wider epidemic (EFSA, ECDC and EURL, 2022), which also includes Russia, Iraq and Kazakhstan (Lewis et al., 2021; Verhagen et al., 2021).

The serological test results by species in 2021 are consistent with findings from previous years. The highest risk of circulation of LPAIVs remains in aquatic birds (game birds, geese and ducks), while gallinaceous birds (in particular chickens and turkeys) were at low risk overall. While backyard establishments and conventional laying hens accounted for the largest numbers tested, only 3 and 1 seropositive PEs were identified, respectively. In Commission Delegated Regulation (EU) 2020/689, and as from April 2021, MSs are required to carry out a complementary risk‐based surveillance aiming to detect clusters of establishments (in time and geographical proximity) infected with LPAIVs. The poultry categories in which this surveillance is recommended include the poultry categories in which most of the positive serological test results have been found in recent years.

Active surveillance provides useful insights into the circulation of AIVs in PEs, in particular for LPAIVs and poultry species or categories which are mostly subclinically affected. However, the sensitivity of such surveillance approach remains limited, as it does not provide high coverage in terms of population and time. Therefore, the results obtained from different surveillance approaches should be considered when interpreting the present results.

According to Commission Decision 2010/367/EU10, MSs shall follow up on PEs with positive serological test results by performing PCR tests on the same flock and/or neighbouring flocks. Follow‐up PCR test results were not available for 7 of the seropositive PEs at the time of writing this report. It is important to note that no investigation identifiers were available at the time of the analysis. Therefore, if follow‐up testing was conducted on neighbouring flocks rather than on the same flock (i.e. with a different holding identifier), these events could not be linked, and the seropositive event would have been classified as not followed up. The current data collection allows reporting of follow‐up activities (‘sampInfo_origSampId’), and RCs are recommended to use this feature accordingly.

Finally, it is important to note that no data on the distribution and composition of the underlying poultry population were available to EFSA. Understanding the underlying population for the different poultry categories would improve interpretation of the AI surveillance results at European level.

The number of wild birds tested by passive surveillance in 2021 was substantially higher than in 2020 and 2019. Twenty‐six out of 31 RCs sampled more wild birds by passive surveillance than in the previous year. Some countries also reported a large number of wild birds sampled under active surveillance activities (e.g. Belgium and Germany).

While 878 wild birds sampled tested positive for HPAIVs in 2020, a larger number of wild birds tested positive for HPAIVs in 2021. Out of the 2,314 HPAIV‐positive wild birds, 2,220 were found dead, identified by passive surveillance programmes. These values continue to support the importance of this surveillance approach for AI surveillance in wild bird species. A large proportion of both sampling and HPAIV‐positive test results occurred in the first and fourth quarters of 2021, confirming that the aforementioned epidemic of HPAI A(H5N8) in RCs in poultry is linked to a similar virus circulation in wild birds.

The respective proportions of wild birds sampled by passive surveillance and HPAIV‐positive wild birds belonging to the list of target species recommended by EFSA remain relatively low (41% and 53% in 2020 and 2021, respectively). The present results suggest that the list could be adjusted with recent knowledge about the species of interest depending on their likelihood of dying when infected with HPAIVs.

Only half of all wild birds sampled were fully identified at species level. Effort should therefore be placed in developing and providing training for species identification.

Summary data provided by the EBP project are presented (Appendix F) to describe the number of wild bird observations reported by voluntary contributors in 2021. These data may provide some context regarding the performance of passive surveillance of AI in wild birds in the EU. However, it is important to note that the density of wild bird observations is the product of two factors:

the density of wild birds (which depends on species‐specific factors such as the location, biotope, time of the year, etc.).

the probability that a wild bird is observed by someone and reported in a relevant database, given that it is present. This is also known as the ‘effort’ put into wild bird observations.

As a consequence, areas with low density of observations may correspond to areas where the sensitivity of passive surveillance is low due to a lower ‘effort,’ or to habitats which are simply not favourable to birds (low density of birds), or both. A previous study in Sweden warned that voluntary contributor‐based data should be used with care, given the limitations of this data collection method (Snäll et al., 2011). Despite the limitations of the voluntary observation data presented in this report, and until further spatial modelling of the distribution of wild birds in Europe by species is readily available, the maps presented in this report (and also those linked to this report and shown in Zenodo), may help to shed light on areas where the wild birds of the species belonging to the target list may gather, supporting RCs in carrying out more targeted surveillance activities.

Methods

Framework for reporting

The development and implementation of active and passive surveillance programmes in poultry and wild birds in MSs is currently supported by Regulation (EU) 2016/429, which lays down the rules related to the EU surveillance programme for avian influenza, with Commission Delegated Regulation (EU) 2020/689 providing the technical requirements, such as objectives, scope and methodological principles, and Commission Decision 2010/367/EU providing more detailed guidelines for poultry and wild birds. Commission Implementing Regulation (EU) 2020/200211 lays down the procedures related to Union notification and Union reporting, while diagnostic procedures for testing the samples collected by the surveillance programmes are outlined in the Diagnostic Manual for avian influenza as set out in Decision 2006/437/EC12.

Data and data processing

Data collation and validation as well as exploratory and statistical analysis were carried out using the statistical software R (R Core Team, 2021).

In some RCs, PEs were sampled several times throughout the year, which was the case for PEs containing one or different poultry categories. For the purpose of this report, each sampling exercise taking place on a specific date, in a specific PE and targeting a specific poultry category was considered as an independent event and counted as one PE sampled. As a result, an overestimation of the total number of PEs sampled may occur for some RCs, with this number being higher than the total number of PEs of a specific poultry category in a specific RC. Therefore, the numbers reported in this report as ‘PEs sampled’ should be interpreted as the numbers of sampling events taking place in a RC for each of the reported poultry categories. Throughout the report, the term ‘number of PEs sampled’ refers to all PEs sampled, regardless of the type of tests conducted on the samples (serology or virology).

For the wild bird data analysis, data submitted by RCs as the year of sampling (‘sampY’), month of sampling (‘sampM’) and day of sampling (‘sampD’) were used as sampling date. As for the 2018, 2019 and 2020 reports, the updated EFSA list of target species (Table E.1 in Appendix E) was used instead of the target list provided in Commission Decision 2010/367/EU. Pooled testing takes place in some MSs when more than one wild bird from the same species are collected at the same time and location (as indicated by variable ‘sampMethod’). In such cases, the variable ‘sampSize’ was used to report the number of wild birds from which samples were pooled. When positive results were obtained from pooled samples (this occurred with pools of up to five wild birds), all the birds included in the pool were considered positive, given that no further information was available.13

Eurostat reference shapefiles were used to create the maps: ‘Countries 2020’ (version 3/6/2019) and ‘NUTS 2016’ (version 19/8/2019). These versions were used to match the units reported in the surveillance data for 2021. Maps plotting the geographical distribution of the sampling events and the location of positive results were aggregated at NUTS2 level for both poultry and wild birds in the present report. However, maps at NUTS3 level are also provided as high‐quality images on the EFSA website, for countries which provided data at NUTS3 level. To summarise sampling activities, the intensity of sampling, calculated as the number of samples taken within a NUTS2 region per 100 km2, was displayed, given that the total number of PEs present in a given region was not available. Samples with location coordinates which could not be matched to a NUTS region from the country reporting the data are not displayed in the maps, but they are accounted for by all other figures and tables in the document.

The results presented in this report are based on the data reported to EFSA by RCs. As a result, data may differ, particularly with regard to HPAIV detections in wild birds, from data reported to the Animal Disease Information System (ADIS) or individual national surveillance databases.

Animal Disease Information System

Avian influenza

Avian influenza virus

European Bird Census Council

EuroBird Portal

Haemagglutinin

Highly pathogenic avian influenza

Highly pathogenic avian influenza virus

Low pathogenic avian influenza

Low pathogenic avian influenza virus

Member State

Neuraminidase

Nomenclature of Territorial Units for Statistics

Polymerase chain reaction

Poultry establishment

Reporting country

Virus isolation

Appendix I – Country data sets

Table I.1 Links to the AI data sets for 2021 by RC. All country data sets containing the tables on the occurrence of AI per country are available on the EFSA Knowledge Junction community on Zenodo. The countries that submitted data sets on the 2021 surveillance data this year are: the 27 EU MSs, United Kingdom (Northern Ireland) and 3 non‐EU MSs

Country	Link to the data set
EU MSs
AT	https://doi.org/10.5281/zenodo.6794634
BE	https://doi.org/10.5281/zenodo.6794740
BG	https://doi.org/10.5281/zenodo.6794811
CY	https://doi.org/10.5281/zenodo.6794832
CZ	https://doi.org/10.5281/zenodo.6796827
DE	https://doi.org/10.5281/zenodo.6796855
DK	https://doi.org/10.5281/zenodo.6796876
EE	https://doi.org/10.5281/zenodo.6796892
EL	https://doi.org/10.5281/zenodo.6796910
ES	https://doi.org/10.5281/zenodo.6796946
FI	https://doi.org/10.5281/zenodo.6796988
FR	https://doi.org/10.5281/zenodo.6797019
HR	https://doi.org/10.5281/zenodo.6797057
HU	https://doi.org/10.5281/zenodo.6798653
IE	https://doi.org/10.5281/zenodo.6798657
IT	https://doi.org/10.5281/zenodo.6798665
LV	https://doi.org/10.5281/zenodo.6798667
LU	https://doi.org/10.5281/zenodo.6798679
LT	https://doi.org/10.5281/zenodo.6798692
MT	https://doi.org/10.5281/zenodo.6793344
NL	https://doi.org/10.5281/zenodo.6798704
PL	https://doi.org/10.5281/zenodo.6798709
PT	https://doi.org/10.5281/zenodo.6798719
RO	https://doi.org/10.5281/zenodo.6798739
SI	https://doi.org/10.5281/zenodo.6798748
SE	https://doi.org/10.5281/zenodo.6798767
SK	https://doi.org/10.5281/zenodo.6798775
XI	https://doi.org/10.5281/zenodo.6798804
Non‐EU MSs
CH	https://doi.org/10.5281/zenodo.6793371
IS	https://doi.org/10.5281/zenodo.6798885
NO	https://doi.org/10.5281/zenodo.6798906