SARS in a hospital visitor and her intensivist

Sir,

Severe acute respiratory syndrome (SARS) is a novel infectious disease in humans caused by a coronavirus that was first recognized in Southeast Asia in late February 2003.¹ The World Health Organization (WHO) has issued definitions for probable and suspected cases.² Most transmissions occurred by close hospital or household contact with infected individuals suggesting a predominant droplet mode of spread.³ Widespread use of personal protective equipment (PPE) including N95 respirators is thought to have been instrumental in controlling the epidemic. We report a patient who had had no direct contact with SARS patients and who subsequently transmitted the infection to her intensivist who was wearing standard PPE during a bronchoscopy.

A 43-year-old woman was admitted to our hospital with a respiratory and systemic illness of 1-week duration. She had had no direct contact with any patients suffering from SARS, but had visited a friend with hepatitis in hospital who was at least two cubicles (approximately 10 m) away from a patient later confirmed to have SARS. On examination, she was tachypnoiec and febrile. Chest radiography revealed bilateral basal consolidations and the white blood cell count was 19.3×10⁹/L (polymorphs 90%, lymphocytes 4%). Community-acquired pneumonia was diagnosed and the patient was isolated in a single room with negative pressure and started on intravenous antibiotics. The following day, she required endotracheal intubation and mechanical ventilation. Over the next four days, she developed multi-system organ failure and adult respiratory distress syndrome requiring haemofiltration and vasopressor support and died on the eighth day of admission. Cultures of blood, urine and bronchoalveolar lavage (BAL) were negative for micro-organisms including fungi and mycobacteria.

Three days after the bronchoscopy, the intensivist (K.-H.L.) who performed the procedure developed fever and myalgia and was subsequently diagnosed as having SARS with pneumonia, despite wearing a N95 mask, glasses, gown, and gloves throughout the procedure. He required admission to intensive care unit and mechanical ventilation, and survived the episode.

The patient's serology was positive for SARS by a dot-blot immunoassay using a viral lysate in a post-mortem analysis of a serum sample taken on day three of admission. Her intensivist was also sero-positive 4 weeks after hospitalization.

Our patient met the revised WHO criteria² for SARS except that she did not ‘care for, live with, or have had direct contact with respiratory secretions and body fluids of a person with SARS,’ as the WHO defines close contact.² Her serology was only found to be positive at post-mortem. To our knowledge, fomite spread has not been well documented for SARS, although it has been demonstrated experimentally for other respiratory viral pathogens, and is the probable route of transmission for our patient. Environmental contamination is the most likely route of transmission in Hotel M, which triggered off the worldwide outbreak of SARS¹ and in the large Amoy Gardens outbreak.⁴ Transmission to a bronchoscopist has not, to our knowledge, been documented before. During the procedure the doctor wore an N95 mask, glasses, gloves, footwear and disposable gown. However, he was not using specific eye protection and a powered air purifying respirator (PAPR) hood, which has become common practice since then.

This case suggests that if the viral load is high the N95 mask may not offer sufficient protection during high-risk procedures, including bronchoscopy, nebulizer therapy or intubation. This is similar to the experience in Canada in which transmission of SARS to protected healthcare workers occurred during a difficult intubation.⁵ We believe that high-risk procedures such as intubation or bronchoscopy may require a higher level of protection than N95 respirators. We also feel that more work needs to be done to establish the role of environmental surfaces in the indirect transmission of the virus to individuals without direct contact. These will be important for future strategies for SARS.