SARS: health care work can be hazardous to health

Severe acute respiratory syndrome (SARS) is possibly the first globally significant occupational disease to emerge in the twenty-first century. It first surfaced in Guangdong, China, in November 2002, made its appearance in Hong Kong in February 2003, and then subsequently spread by air travel to Vietnam, Singapore and Canada. SARS has now encircled the globe, affecting 30 countries. As of 13 May, the World Health Organization (WHO) 1 reported 7548 probable SARS cases and 573 deaths. The case fatality ratio varies from 0 to 50%, depending on the age of the patient, with an overall estimate of 14–15% 2. These figures will undoubtedly change with time as more cases emerge. The aetiological agent is a novel coronavirus (SARS-CoV), with patterns of spread suggesting droplet or contact transmission 3,4. Clinical features are those of atypical pneumonia, with the common presenting symptoms being fever and dry cough. SARS patients are classified as either ‘suspect’ or ‘probable’ cases 5. A suspect case is a patient who presents with a history of high fever (>38°C) and a cough or breathing difficulty. In addition, there must be one or more of the following exposures within 10 days of the onset of symptoms: either a close contact with a person who is a suspect or probable case of SARS, or a history of travel to a SARS-affected area. A suspect case is upgraded to ‘probable’ with the appearance of radiological changes consistent with pneumonia or respiratory distress syndrome (RDS), or in the event of death, autopsy findings consistent with the pathology of RDS without an identifiable cause. At the time of writing, there is no validated, widely and consistently available laboratory test for infection with the SARS-CoV. However, from 1 May 2003, the WHO amended the definition of a probable case to include a suspect case of SARS who has positive laboratory tests for SARS-CoV, under conditions drawn up by the WHO. Empirical therapy for SARS has included corticosteroids, a broad spectrum antiviral agent and antibacterial cover 6. Health care workers (HCWs) are a high-risk group for SARS-CoV infection. According to the WHO, they constitute the biggest, single group of probable SARS patients worldwide. As at 4 May, 41% of 203 SARS patients in Singapore and 22% of 1629 cases in Hong Kong 7 were HCWs. The majority of cases in Canada (74.4%) have been attributed to exposure in a hospital or health care setting 8. As at April 25, more than 100 hospital workers at three Greater Toronto Area hospitals have become ill with SARS 9. Unfortunately, a number of deaths have occurred among HCWs. An early casualty was Dr Carlo Urbani, the WHO expert working in Hanoi who was among the first to identify the clinical disease, and in whose honour it has been proposed that the causative agent bear his name. The index case (and first reported death) of the Hong Kong outbreak was an elderly Chinese physician who had treated SARS patients in Guangdong. Three doctors, two nurses and a health care attendant in Singapore have also succumbed to SARS. The vulnerability of HCWs can be explained by their close contact with patients. The innocuous, ‘flu-like’ clinical presentation of SARS does not help to raise the index of suspicion. In the early stages of the outbreak, there was also not the same degree of vigilance with regards to potentially high exposure situations such as aerosol-generating procedures. These included aerosolized medication treatments (i.e. nebulizers), the use of high-flow Venturi masks and non-invasive positive pressure ventilation for SARS patients, airway suctioning and endotracheal intubations. As a poignant illustration, in Singapore, a cluster of 41 probable and 21 suspected cases was traced to a single SARS patient who was initially undiagnosed for 10 days and treated for gastrointestinal bleeding, chronic kidney disease and diabetes 10. The cluster included 26 hospital staff working as doctors, nurses, radiographers and housekeepers. An occupational health audit, which included a walk-through of the hospital ‘hot spots’ carried out by the authors, revealed a small number of deficiencies which could well be weak links in an otherwise strong preventive chain. That the cluster of cases included housekeepers is also significant—preventive measures need to target much broader groups of HCWs than just the doctors and nurses in direct contact with patients. Frontline HCWs like counter clerks, porters and ambulance drivers are also at risk, and must be educated and protected. The encouraging news is that with the institution of stringent infection control measures and personal protection, the situation appears to have improved somewhat. This was the case in a Singapore hospital 11, where the experience was reported as: ‘We did not see any further transmission from this index patient after we implemented strict infection control measures involving use of N95 masks, gown, gloves, and handwashing before and after patient contact’. Doctors in Hong Kong 12 are also ‘hopeful that further cases among our staff will be