INTRODUCTIONSince the emergence of the pandemic influenza A/H1N1/2009 virus in April 2009, diagnostic testing in many countries has revealed the rapid displacement and then replacement of circulating seasonal influenza viruses by this novel virus.

MATERIALS AND METHODSIn-house seasonal and pandemic influenza-specific polymerase chain reaction assays were introduced and/or developed at the Molecular Diagnosis Centre (MDC) at the National University Hospital (NUH), Singapore. These assays have been used to test all samples received from in-patients, out-patients, staff and visitors for suspected pandemic influenza A/H1N1/2009 infection.

RESULTSPrior to the arrival of the pandemic A/H1N1/2009 virus in Singapore at the end of May 2009, seasonal influenza A/H3N2 predominated in this population, with very little seasonal influenza A/H1N1 and B viruses detected. Within about 1 month of its arrival in Singapore (mainly during June to July 2009), this pandemic virus rapidly displaced seasonal influenza A/H3N2 to become the predominant strain in the Singaporean population served by MDC/NUH.

CONCLUSIONSRealtime molecular techniques have allowed the prompt detection of different influenza subtypes during this current pandemic, which has revealed the displacement/replacement of previously circulating seasonal subtypes with A/H1N1/2009. Although some of this may be explained by immunological cross-reactivity between influenza subtypes, more studies are required.

Communicable Diseases, Emerging ; Cross Reactions ; Disease Outbreaks ; Humans ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza B virus ; isolation & purification ; Influenza, Human ; classification ; diagnosis ; epidemiology ; Influenzavirus C ; isolation & purification ; Molecular Diagnostic Techniques ; Polymerase Chain Reaction ; Singapore ; epidemiology

INTRODUCTIONSingapore was one of 29 countries worldwide affected by severe acute respiratory syndrome (SARS) in 2003.

MATERIALS AND METHODSThere were 238 cases identified during the outbreak. We performed a retrospective analysis of the clinical and laboratory data of 234 patients admitted to Tan Tock Seng Hospital and Singapore General Hospital.

RESULTSThe mean age of patients was 21 years, 31.6% of patients were males and 41.8% were healthcare workers. At presentation, the common symptoms were fever, myalgia, cough and headache; rhinorrhoea was uncommon. On admission, 21% had leukopenia, 18% had thrombocytopaenia, 29% had hyponatraemia, 31% had hypokalaemia, 21% had transaminitis. Polymerase chain reaction (PCR) testing of respiratory and stool samples provided the best yield at the end of the first week of illness. Thirty-two patients were initially not recognised as probable SARS and were reclassified when the serology test results were available. The chief reasons for not identifying these patients early were persistently normal chest X-rays (68.8%), very mild presentation (43.8%) and the presence of a concomitant illness (12.5%). Overall, 12% of the patients were probable SARS with atypical presentations. Overall mortality was 11.8%.

CONCLUSIONPatients infected with the SARS coronavirus had a wide clinical presentation with non-specific symptoms.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Antibodies, Viral ; analysis ; Child ; Child, Preschool ; DNA, Viral ; analysis ; Diagnosis, Differential ; Female ; Humans ; Incidence ; Infant ; Male ; Middle Aged ; Retrospective Studies ; Reverse Transcriptase Polymerase Chain Reaction ; SARS Virus ; genetics ; immunology ; Severe Acute Respiratory Syndrome ; diagnosis ; epidemiology ; virology ; Severity of Illness Index ; Singapore ; epidemiology