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 > or =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 > or =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.