Severe acute respiratory symptoms and severe acute respiratory syndrome.

Common and novel respiratory viruses can occasionally cause epidemics of viral pneumonitis with severe acute respiratory symptoms (sars). In 2003, World Health Organisation (WHO) coined the word SARS for Severe Acute Respiratory Syndrome in patients with a relevant travel/contact history and sars 1, 2, 3, 4, 5. The WHO case definition of suspected SARS was fever, respiratory symptoms and close contact with SARS patients or history of travel to an epidemic area (http://www.who.int/csr/sars/casedefinition) 3. Aetiologic diagnosis was unnecessary in the clinical definition, so patients clinically diagnosed with SARS may not have the SARS coronavirus 5. Any patient in an epidemic area with fever and cough would be diagnosed as SARS by WHO definition in 2003. The clinical features are essentially the same as for any respiratory viral infections or pneumonitis. Towards the end of the 2003 epidemics, SARS coronavirus was identified to be the culprit, and the definition incorporated the aetiologic agent. This laboratory definition downplays the importance of disease severity and symptomatology, so patient with mild respiratory symptoms or even non‐respiratory symptoms could still be diagnosed as SARS if coronavirus is isolated. Conversely, patients with sars but no coronavirus isolated were not considered as SARS. The term has shifted from clinical diagnosis to a virologic diagnosis. Subsequently, it was realised that the clinical features of many patients with laboratory SARS were neither ‘severe’ nor ‘respiratory’ in nature. Nevertheless, imprecise definition carries serious public health implications that patients may be erroneously quarantined and cities stigmatised.

Since 2003, many new surveillance guidelines and confusing abbreviations appeared in the city of Hong Kong. For instance, ‘ILI’ represents influenza‐like illness [including upper respiratory tract infection (URTI) or upper respiratory infection or illness (URI)], ‘HSI’ for human swine influenza (i.e. novel H1N1‐2009), RD for respiratory disease or respiratory distress, and ards for acute respiratory diseases (which is not the same as ARDS for Adult Respiratory Distress Syndrome or Acute Respiratory Distress Syndrome for children). The definitions for many of these abbreviations are nearly identical as the clinical definition of SARS (i.e. respiratory symptomatology ± fever ± contact). This can be unnecessarily confusing. Indeed, the only difference between ILI, influenza, avian flu, swine flu, ards and SARS is the virus, and all may result in ARDS (Table 1)! Health organisations don't have to create a new abbreviation each and every time. Applying the initial clinical definition of SARS, these patients might all have SARS because their symptoms and epidemiologic links are just like SARS (Table 1) 3.

Table 1

Comparing SARS, Avian influenza and Severe Acute Respiratory Infections associated with coronavirus infection

Virus	SARS	Avian influenza	Severe acute respiratory infections associated with coronavirus infection
	SAR‐CoV	H5N1, H9N1	London1_novel CoV 2012
Origin	Fu Shan City, China	Vietnam and others	Qatar
Source	Civet cat, wild animals	Birds, poultry	Possible wild animal
Spread	Animal to human, then human‐to‐human	Avian to human, limited human‐to‐human	Human‐to‐human (one case)
Principal symptoms	Fever, respiratory	Fever, respiratory	Fever, respiratory
Travel history	Yes	Yes	Probably yes
Morbidity and mortality	8000 infected	400 infected	13 infected
	700 deaths	300 deaths	6 death
Mortality	Low	High	? 46%
Antivirals and treatment	Supportive, ribavirin +corticosteroid	Supportive, oseltamivir	Nil, supportive

SARS has seemingly disappeared from the planet. However, the term was raised from time to time for suspicious conditions 5. On 22 September 2012, the United Kingdom informed WHO of a case of ‘acute respiratory syndrome’ with renal failure in a previously healthy, 49‐year‐old male Qatari national with travel history to Saudi Arabia and Qatar. The Health Protection Agency has confirmed the presence of a novel coronavirus (human betacoronavirus 2C) and compared the sequencing with that of a virus obtained from lung tissue of a fatal case in a 60‐year‐old Saudi national previously sequenced by the Erasmus Medical Centre in the Netherlands. This comparison indicated 99.5% identity. WHO coined the interim case definition of ‘severe respiratory disease associated with novel coronavirus’ on September 25, which was revised on September 29 to Severe Acute Respiratory Infections associated with novel coronavirus infection. It is interesting to note that the definition of SARS for surveillance is not used despite that symptoms and viral aetiology all fulfilled the SARS definition. The Department of Health in Hong Kong now includes ‘Severe Respiratory Disease associated with Novel Coronavirus’ as a statutorily notifiable disease. On October 3, a 4‐year‐old boy came to Hong Kong from Saudi Arabia with his father. On October 7, he developed symptoms of fever and severe respiratory illness and was quarantined on the same day. The Center for Health Protection (CHP) of Hong Kong's Department of Health (DH) tested specimens drawn from the boy's airway and found he had H1N1 flu, not novel coronavirus. The boy's father also had a fever 2 days before the boy caught the disease, but recovered. Now that the winter flu season is approaching, CHP and DH will keep themselves busy with many cases of sars or ards to come.

In medicine, a definition or syndrome representing ‘a constellation of symptomatology seen in association’ should stand the trial of time after it is coined. We always teach medical students to avoid confusing abbreviations. It is high time we finalise a time‐proof definition for these epidemic viral pneumonitis 2, 3. Health organisations should provide consistent definitions for index surveillance, epidemiological and prognostication studies. Although the SAR‐Coronavirus (CoV) is out and may never come back, SARS and sars were and are very much alive among us 5.

Based on our 2003 definitions, we propose the term epidemic pneumonia (EP) and the following surveillance classification to replace all these existing and prospective confusing respiratory terminology: This classification may be useful for index surveillance and in epidemiological and prognostication studies. It is not intended for triaging of patients because there may not be any radiographic abnormality at presentation. Virology or bacteriology results may be available only a few days later. Applying this classification to the recent coronavirus epidemics, patients could be classified as EP [C+, Coronavirus+], EP [C−, Coronavirus+], EP [C+, e.g. Mycoplasma pneumoniae+], and so on. EP [C+, P−] and EP [C−, P−] represent an overdiagnosed group of patients with various atypical pneumonia syndromes. Our classification also provides unequivocal guides on patient management. Newly admitted patients with persistent fever and pneumonia should be isolated and be eventually classified into one of the four forms of EP. Patients with EP [C+, P−] and EP [C−, P−] could be discharged once their symptoms subsided.

EP with positive contact or travel history and pathogen identified.

EP with positive contact or travel history but no pathogen identified.

EP with negative contact or travel history but pathogen identified.

EP with negative contact or travel history and no pathogen identified.