Severe Acute Respiratory Syndrome–Associated Coronavirus Infection in Toronto Children: A Second Look

OBJECTIVES. During the severe acute respiratory syndrome outbreak of 2003, there was an impetus to provide clinical information to the medical community in a timely manner. Accordingly, a preliminary report of our experience of suspected severe acute respiratory syndrome–associated coronavirus infections in children was published without microbiological findings. This report provides an update on pediatric severe acute respiratory syndrome–associated coronavirus infections in Toronto, Ontario, Canada, that includes microbiological findings. METHODS. All of the children admitted to the Hospital for Sick Children between March 14 and June 15, 2003, with suspect severe acute respiratory syndrome–associated coronavirus infection were included. A proven case was defined as one that fulfilled the clinical criteria for suspect severe acute respiratory syndrome–associated coronavirus infection and demonstrated a serologic response to severe acute respiratory syndrome–associated coronavirus. Serology results, from a neutralizing antibody assay, were considered positive if the sera inhibited the development of a severe acute respiratory syndrome–associated coronavirus-specific cytopathic effect at a dilution of ≥1:8. RESULTS. Neutralizing antibody to severe acute respiratory syndrome–associated coronavirus was demonstrated in 8 of 25 children admitted with suspect severe acute respiratory syndrome–associated coronavirus infection. In 3 of these 8 children, severe acute respiratory syndrome–associated coronavirus was also detected by reverse-transcription polymerase chain reaction in the stool. All 8 had documented exposure to ≥1 severe acute respiratory syndrome–associated coronavirus-infected adults residing in the same household. Exposure that was limited to visiting a Toronto hospital at which severe acute respiratory syndrome–associated coronavirus-infected patients were admitted or travel from a country in which severe acute respiratory syndrome had been reported did not result in documented infection in any of our cases. On the basis of our clinical case definition, 6 of 8 microbiologically confirmed case had been classified as having probable severe acute respiratory syndrome–associated coronavirus infection. Clinical disease was mild, nonspecific, and self-limited and was indistinguishable from that reported with other common respiratory viruses. CONCLUSIONS. The factor most strongly associated with severe acute respiratory syndrome–associated coronavirus infection in Toronto children was a history of close contact with an adult severe acute respiratory syndrome–associated coronavirus case. This serves to reinforce the importance of routinely obtaining a thorough epidemiologic travel and exposure history for all subjects with suspected infectious diseases.