Severe respiratory syndromes: Travel history matters

Summary

History of travel or contact is an important clue to emerging infections. 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. The WHO case definition of suspected SARS was fever, respiratory symptoms and close contact with SARS patients or travel history to an epidemic area. The clinical features are essentially the same as for any respiratory viral infections or pneumonitis. Since 2003, many new surveillance guidelines and confusing abbreviations appeared in the city of Hong Kong. In 2012, another outbreak of coronavirus pneumonitis occurred in the Middle-East. More case definitions such as MERS (Middle East Respiratory Syndrome) and SARI (Severe Acute Respiratory Infections) were coined for the viral pneumonitis. In medicine, a definition or syndrome representing “a constellation of symptomatology seen in association” should stand the trial of time after it is coined. Health organisations should provide consistent definitions for index surveillance, epidemiological and prognostication studies. Travel or contact history is pivotal in formulating management protocol during any outbreak when the pathogen is not initially clear.

History of travel or contact is an important clue to emerging infections as evidenced in coronavirus in 2003 and 2012, swine influenza in 2009 and avian influenza in 2013. 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]. (http://www.who.int/csr/sars/casedefinition). 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-cornoavirus was identified to be the culprit. 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, numerous new surveillance guidelines and confusing abbreviations appeared in the city of Hong Kong. The definitions for many of these abbreviations are nearly identical as the clinical definition of SARS (i.e. respiratory symptomatology ± fever ± contact). 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], [6].

Table 1.

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

Virus	SARS SAR-CoV	Avian influenza H7N9	MERS or SARI London1_novel CoV 2012
Origin	Fu Shan city, China	China	Quatar
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, renal
Travel history	Yes	Yes	Yes
Morbidity and mortality	8000 infected 700 deaths	131 infected 31 deaths	41 infected 20 death
Mortality	Low	High (24%)	High (50%)
Antivirals and treatment	Supportive, ribavirn + corticosteroid	Supportive, oseltamivir	Nil, supportive

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 (HPA) has confirmed the presence of a novel coronavirus (human betacoronavirus 2C). 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 (SARI associated with nCoV). 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. The virus was termed the Middle East Respiratory Syndrome Coronavirus. (MERS-CoV) by some investigators. From September 2012 to date, WHO has been informed of a global total of 41 laboratory-confirmed cases of infection with the nCoV, including 20 deaths. Several countries in the Middle East have been affected, including Jordan, Qatar, Saudi Arabia, and the United Arab Emirates (UAE). Cases have also been reported in France, Germany, and the United Kingdom. All of the European cases have had a direct or indirect connection to the Middle East, including two cases with recent travel history from the UAE. In France and the United Kingdom, there has been limited local transmission among close contacts who had not been to the Middle East but had been in contact with a traveller who recently returned from the Middle East (http://www.who.int/csr/don/2013_05_18_ncov/en/index.html). In recent months, WHO appears to move away from coining confusing new “syndromes” and encourages all Member States to continue their surveillance for Severe Acute Respiratory Infections (SARI) related to the novel coronavirus. In addition, WHO recommends any clusters of SARI or SARI in health care workers should be thoroughly investigated regardless of where in the world they occur. The term SARS is now only reserved for the 2013 SARS coronavirus associated disease.

In medicine, a definition or syndrome representing “a constellation of symptomatology seen in association” should stand the trial of time after it is coined. Should there be another outbreak of a presumed viral pneumonitis in future, health organisations might run out of terminology to describe the same respiratory syndrome by another pathogen. It is high time we finalise a time-proof definition for epidemic viral pneumonitis [3], [6]. Based on our 2003 definitions [3], we now propose the term epidemic pneumonia (EP) and the following surveillance classification to replace all these existing and prospective confusing respiratory terminology in an ever changing world of epidemics of novel respiratory pathogens:

EP [C+, P+] EP with positive contact or travel history and pathogen identified.

EP [C+, P-] EP with positive contact or travel history but no pathogen identified.

EP [C-, P+] EP with negative contact or travel history but pathogen identified.

EP [C-, P-] EP with negative contact or travel history and no pathogen identified.

EP [C?, P?] EP with contact or travel history and virology/bacteriology pending or not yet identified.

This classification may be useful for index surveillance and in epidemiological and prognostication studies. Applying the EP classification to the recent coronavirus epidemics, patients could be classified as EP [C+, nCoV+], EP [C-, nCoV+] 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 in endemic areas 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.

In 2013, an 11-year-old girl presented to a Hong Kong PICU with sars, ARDS (acute respiratory distress syndrome), right-sided pneumonia and pleural effusion. Streptococcus pneumoniae was not isolated in this girl with “typical” pneumonia by symptomatology and chest radiography, but nasopharyngeal aspirate yielded mycoplasma pneumoniae instead. A few months later, a 2-year-old girl was taken to the same PICU following extensive investigations in Xiamen, China for extreme failure-to-thrive and pneumonia but no definitive diagnosis arrived. She was confirmed with HIV infection the next day in Hong Kong. Nasopharyngeal aspirate also yielded CMV by PCR. There was no outbreak of any novel respiratory infection during this period in Hong Kong or Xiamen despite SARI-nCoV in middle east and avian influenza in Mainland China. The patient with mycoplasma pneumonia can be classified as EP [C-, mycoplasma pneumoniae+] and the child with HIV as EP [C-, HIV and CMV and presumed PCP]. In fact, EP can be excluded based on no travel or contact history and CoV isolation.

Health organisations should provide consistent definitions for index surveillance, epidemiological and prognostication studies, and refrain from the temptation of coining unnecessary new terminology to describe essentially the same conditions each and every time when outbreaks of severe respiratory infection occurs [3], [4], [5]. Travel or contact history is pivotal in formulating management protocol during any outbreak when the pathogen is not initially clear.

Conflict of interest

The author has published on the subject matter of SARS.