Pandemic (H1N1) 2009: clinical and laboratory findings of the first fifty cases in Singapore.
BACKGROUND
Since the fi rst imported case on 26 May 2009, pandemic (H1N1) 2009 has spread from travellers and has resulted in sustained community transmission. Singapore began with a strict containment policy where all suspected and confirmed cases of pandemic (H1N1) 2009 were admitted for testing. We describe here the clinical and laboratory characteristics of the fi rst 50 adult cases with confirmed pandemic (H1N1) 2009.


METHODS
A review was conducted of medical notes of adult patients with confirmed pandemic (H1N1) 2009 by polymerase chain reaction assay from combined nasal and throat swabs admitted to the Communicable Disease Centre, Tan Tock Seng Hospital.


RESULTS
From 26 May to 18 June 2009, 50 patients with a median age of 27 years old were admitted at a median of 3 days from illness onset. Half were male and all were travellers arriving in Singapore. Non-Singaporean citizens (38%) and other ethnic groups (40%) were over-represented. History of fever was reported in 90% and respiratory symptoms in 92%. Gastrointestinal symptoms were uncommon, present in 4% only. Temperatures on presentation of >or=38.0 degrees C, >or=37.8 degrees C and >or=37.5 degrees C were present in 48%, 56% and 76%, respectively. Only 46% of patients met the United States Centers for Disease Control and Prevention (US CDC) case definition of influenza-like illness (ILI). Clinical and laboratory findings were unremarkable for the majority. All cases were treated with oseltamivir and had uncomplicated recovery.


CONCLUSIONS
Pandemic (H1N1) 2009 had mild clinical and laboratory findings in immunocompetent patients. Use of the US CDC ILI criteria alone would have detected less than half of confirmed cases.
Chan
Monica
M
Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore.
Chen
Mark I
MI
Chow
Angela
A
Lee
Caroline P S
CP
Tan
Adriana S H
AS
Lye
David Chien
DC
Leo
Yee Sin
YS
D000328:Adult; D021821:Communicable Diseases, Emerging / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012846:Singapore / Q000453:epidemiology; D055815:Young Adult