The canary Serinus canaria (Passeriformes: Fringillidae) as a new host for Isospora bioccai in Mexico.

Isospora bioccai (Cringoli and Quesada 1991) (Protozoa, Apicomplexa, Eimeriidae) is reported and described from captive canaries Serinus canaria forma domestica (Linnaeus 1758) in Mexico. The oöcysts are subspherical, 25.5 × 23.5 μm, with smooth, bilayered wall, ∼1.3 μm thick. Micropyle absent, oöcyst residuum absent, and polar granule present, 4-8 rice-grain-shaped. Sporocysts are ovoidal, 16.7 × 10.5 μm. Stieda body knob-like and substieda body trapezoidal of irregular base. Sporocyst residuum is composed of granules of different sizes. Sporozoites are vermiform with one refractile body and a nucleus. Gamogony was seen in the duodenum. In addition to new locality, this is the first description of I. bioccai from S. canaria.

Introduction

Serinus (canaries) is a genus of finches belonging to the Fringillidae family of birds, mostly confined to Africa and the Mediterranean Basin (Arnaiz-Villena et al., 1999). Particularly, S. canaria (Linnaeus 1758) is native from the Canary Island and now is widely kept in captivity in most areas of the world (IUCN, 2017). In Mexico, canaries S. canaria are available at pet shops and through bird traders, called pajareros, which is a local name given to the trade (derived from pájaro, the Spanish word for bird) (Roldán-Clarà et al., 2017). The aim of this study was the description of I. bioccai from S. canaria in Mexico.

Materials and methods

Bird sampling

Twelve captive canary Serinus canaria were investigated as part of a routine parasitology study in a pet shop at Toluca Valley (19º17′32″N; 99º39′14″W), Mexico. Fecal samples were placed in a plastic vial containing 2.5% potassium dichromate solution (K2Cr2O7) 1:6 (v/v) and observed in a light microscope (Duszynski and Wilber, 1997).

Microscopic analysis

To investigate the site of infection, one canary was euthanized (AVMA, 2013; NOM-033-SAG/ZOO-2014), and the following organs and tissues were collected from the bird: trachea, lungs, liver, stomach and intestines. These viscera samples were placed in 10% neutral buffered formalin and processed, sectioned, and stained with hematoxylin and eosin for routine histologic examination. The fecal samples with unsporulated oocysts were placed in a thin layer (5 ml) of K2Cr2O7 in Petri dishes, incubated at 23–28 °C and monitored daily, until 70% of oocysts were sporulated. Oocysts were recovered by flotation in Sheather's sugar solution (S.G. 1.20). Morphological observations, photomicrographs and measurements (n = 30), according Duszynski and Wilber (1997) and Berto et al. (2014), were made using a Nikon Eclipse 80i microscope coupled to a digital camera Nikon DS-Fi2.

Resuls

Four canaries (33.3%) shed oöcysts in the faeces. Initially, the oöcysts were non-sporulated, but approximately 70% of the oöcysts were sporulated at day two (under the conditions used in this study).

Oöcyst (n = 35) were subspherical, 24.1−27.2 × 22.0–25.1 (25.5 × 23.5); length/width (L/W) ratio 1.0–1.1 (1.1). Wall bi-layered, 1.0–1.1 (1.1) thick, outer layer smooth, c. 1/3 of total thickness. Micropyle absent, oöcyst residuum absent and polar granule present, 4–8 rice-grain-shaped (Fig. 1A). Sporocysts (n = 35) 2, ellipsoidal, 9.2−11.2 × 15.6–17.4 (10.5 × 16.7); L/W ratio 1.6–1.8 (1.7). Stieda body present, nipple-like, 1.1 high × 2.4 wide; sub-Stieda present, trapezoidal, irregular base, 1.8 high × 4.5 wide; para-Stieda body absent; sporocyst residuum present, consisting of scattered spherules of different sizes (Fig. 1B; Table 1). Sporozoites 4, vermiform, with single posterior refractile body and centrally located nucleus. Phototypes and line drawings of sporulated oöcysts are deposited and available in the Collection of the Avian Microbiology Laboratory, Centro de Investigación y Estudios Avanzados en Salud Animal. The repository number is ESV-23/2017.

Fig. 1

Oöcyst of Isospora bioccai. A & B. Photomicrographs. Scale-bar: 10 μm.

Table 1

Comparative morphology of Isospora sp. recorded from Fringillidae.

Host	Carduelis atrata (La Fresnaye & D'Orbigny)	Carduelis carduelis (L.)		Carduelis tristis (L.)	Carduelis chloris (L.)		Chloris [Carduelis] sinica		Fringilla coelebs (L.)A	Linaria [Carduelis] cannabina (L.)			Loxops virens (Gmelin)
Species	I. atrataRossi et al. (1996)	I. carduelisGottschalk (1969)	I. lacazei Labbé (1893)B	I. gryphoniOlson et al. (1998)	I. chloridisAnwar (1966)	I. daszakiBall et al. (2012)	I. mcquistioniCringoli and Quesada (1991)	I. bioccaiCringoli and Quesada (1991)	I. fringillaeYakimoff and Gousseff (1938)	I. arruiQuesada and Cringoli (1990)	I. cannabinaeGottschalk (1972)	I. cannabinaQuesada and Cringoli (1990)	I. loxopisLevine et al. (1980)
Locality	Italy (imported from Peru, Bolivia, and Argentina)	Germany	England, Spain	Canada	England, Spain	England	Italy	Italy	Azerbaijan	Italy	Germany	Italy	Hawaii
Reference	Rossi et al. (1996)	Gottschalk (1969)	Anwar (1966); Romero-Rodriguez (1973)	Olson et al. (1998)	Anwar (1966)	Ball et al. (2012)	Cringoli and Quesada (1991)	Cringoli and Quesada (1991)	Yakimoff and Gousseff (1938)	Quesada and Cringoli (1990)	Gottschalk (1972)	Quesada and Cringoli (1990)	Levine et al. (1980)
Oöcyst
Shape	spherical or subspherical	subspherical	subspherical	spherical to subspherical	ellipsoidal	spherical to subspherical	ovoidal	spherical to subspherical	spherical	subspherical to ovoidal	subspherical	spherical or subspherical	subspherical
Wall	bi-layered		bi-layered	bi-layered	one-layered	bi-layered	bi-layered	bi-layered		bi-layered		bi-layered	bi-layered
Length	19.4–23.5 (21.0)	24.69–30.94 (28.19)	20.0–34.0 (26.8)	28.0–34.0 (30.7)	17.3–33.2 (25.4)	16.8–25.2 (20.3)	24.0–28.5 (26.0)	22.0–26.0 (24.0)	16.0–24.0 (21.2)	20.8–29.0 (25.1)	22.19–29.69 (26.13)	24.3–26.6 (24.3)	25.0–26.0 (26.0)
Width	18.5–22.0 (20.3)	20.94–26.25 (23.88)	18.0–30.0 (24.5)	25.0–33.0 (29.2)	16.6–30.0 (22.3)	16.8–22.4 (18.8)	20.0–23.6 (22.6)	21.0–25.8 (23.6)		18.5–22.0 (21.5)	20.94–26.56 (23.88)	23.2–24.3 (24.1)	22.0–25.0 (23.0)
Length/Width ratio	1.0–1.06 (1.03)		1.0–1.5 (1.1)	1.05		1.07–1.1 (1.08)		1.02		1.16		1.04
Polar granuleC	+, (rarely 2), oval	+	+, 1 to 3 splinter-like	2-4 rice-grain-shaped	+, 2 or more ovoidal	–	+, 1 (rarely 2 or 3)	+, 4 to 10 elongated	+	1 (rarely 2) elongated	+	2-4 elongated	–
Oöcyst residuumD	–	–	–	–	–	–	–	–	–	–	–	–	–
Sporocyst
Shape	ellipsoidal	ovoid	pyriform	ovoid	pyriform		ovoid	ellipsoidal	ovoid	ellipsoidal		piriform	ovoid
Length	17.5–18.94 (18.8)	17.34	15.0–19.0	15.0–25.0 (22.2)	13.5–18.5 (15.3)	12.6–18.2 (14.8)	16.0–19.8 (18.1)	18.6–20.0 (19.5)	12.0–14.0	17.4–22.0 (20.9)	13.44–19.06 (16.44)	17.4–20.0 (19.1)	16.0–17.0 (16.0)
Width	9.5–11.0 (10.3)	11.15	9.0–12.0	12.0–14.5 (13.4)	8.3–12.2 (9.4)	8.4–11.2 (9.4)	11.0–12.0 (11.4)	10.0–12.4 (11.6)	8.0–10.0	10.4–11.6 (10.8)	10.94–13.06 (12.33)	10.4–11.6 (11.5)	12.0–13.0 (13.0)
Length/Width ratio	1.76–1.88 (1.82)			1.7		1.6	1.59	1.68		1.93		1.66
Stieda body	flattened	present	present	small	present	opaque	bottlecap-shaped	nipple-like		knob-like	absent	knob-like	knob-like
Sub-Stieda body	rounded		present	indistinct	present	opaque	slightly convex base	trapezoidal		rounded		trapezoidal, irregular base	no
Residuum	compact/diffuse		diffuse or compact	compact	cluster of scattered granules	diffuse	compact	diffuse	present	compact			diffuse

A Also recorded I. chloridis and I. lacazei.

B Also recorded in Passer domesticus (L.).

C Polar granule: +, present; -, absent.

D Oöcyst residuum: +, present; -, absent.

E Also recorded I. chloridis and I. lacazei.

Histological examination of tissues helped detect endogenous stages in the epithelial cells of duodenum (Fig. 2). Endogenous stages develop extranuclearly in the cytoplasm of duodenal epithelial cells. Most of the endogenous stages were observed mainly into epithelial cells along the length of the villi. Meronts were surrounded by a parasitophorous vacuole (Fig. 2) (see Fig. 3).

Fig. 2

Isospora bioccai from the duodenum of a canary Serinus canaria. Meronts (arrowheads) surrounded by its parasitophorous vacuole. Scale-bar: 10 μm.

Fig. 3

Duodenum histological sections of a naturally Isospora bioccai-infected canary Serinus canaria. A. Meronts surrounded by its parasitophorous vacuole. B. A sexual stage. Photomicrographs. Scale-bar: 10 μm.

Discussion

Up to now, the concept of intra-familial specificity of Isospora spp. of passerine birds has been maintained (Berto et al., 2011). The sporulated oocysts obtained in this study were compared in detail with coccidian parasites from other birds that belong to the same host family (Duszynski and Wilber, 1997). The morphology and morphometry of the I. bioccai oocysts allow differentiating it from other Isospora species passerines from the same family (Table 1).

Isospora bioccai was first described from Chloris [Carduelis] sinica in Italy (Cringoli and Quesada, 1991). Phylogenetic analysis of the Fringillidae, showed C. sinica cluster separately from congeneric species and form a distinct lineage in the Serinus-Chloris complex (Zuccon et al., 2012). Further morphometric and phylogenetic analysis of coccidia from Fringillidae are need (Ogedengbe et al., 2016; Yang et al., 2017). In the canary S. canaria have been identified following Isospora species: I. canaria in USA and Brazil (Box, 1975; Berto et al., 2013), I. chloridis in England and Spain (Anwar, 1966; Romero Rodriguez, 1973), I. lacazei in England and Spain (Anwar, 1966; Romero Rodriguez, 1973), I. serini in USA (Box, 1975, 1977), and I. serinuse in Australia (Yang et al., 2015). Unidentified species of coccidia have been reported in captive canary S. canaria in Brazil, (de Freitas et al., 2003; Lima et al., 2017). Similarly, unidentified species of coccidia have been identified in other Fringillidae (Svobodová, 1994; Brown et al., 2010). In addition to new locality, this is the first description of I. bioccai from S. canaria. Fringillidae birds were one of the most common avian families in reported international trade (Bush et al., 2013). In the State of Mexico where Toluca Valley is located, Fringillidae (C. notata, C. psaltria and S. canaria) were one of the most families reported in bird markets (Álvarez et al., 2005). We speculate bird trade as the origin of I. bioccai infection in S. canaria.

Declarations of interests

None.

Conflicts of interest

The authors declare that they have no conflict of interest.

Ethical approval

All applicable national and international guidelines for the care and use of animals were followed (NOM-033-SAG/ZOO-2014; AVMA, 2013).

Funding information

This study was supported by Universidad Autónoma del Estado de México, project UAEM 4328/2017/CI.