Introduction:This paper describes the epidemiological, microbiological and environmental investigations conducted during an outbreak of Salmonella gastroenteritis in Singapore. Methods:A case-control study was undertaken to identify the vehicle of transmission. Microbiological testing was performed on faecal, food and environmental samples. Isolates of Salmonella were further characterized by phage typing and ribotyping. Results:There were 216 gastroenteritis cases reported from 20 November to 4 December 2007. The causative agent was identified as Salmonella enterica subspecies enterica serotype Enteritidis for 14 out of 20 cases tested. The vehicle of transmission was traced to cream cakes produced by a bakery and sold at its retail outlets ( P < 0.001, OR = 143.00, 95% Cl = 27.23–759.10). More than two-thirds of the 40 Salmonella strains isolated from hospitalized cases, food samples and asymptomatic food handlers were of phage type 1; the others reacted but did not conform to any phage type. The phage types correlated well with their unique antibiograms. The ribotype patterns of 22 selected isolates tested were highly similar, indicating genetic relatedness. The dendrogram of the strains from the outbreak showed distinct clustering and correlation compared to the non-outbreak strains, confirming a common source of infection. Discussion:The cream cakes were likely contaminated by one of the ingredients used in the icing. Cross-contamination down the production line and subsequent storage of cakes at ambient temperatures for a prolonged period before consumption could have resulted in the outbreak.

INTRODUCTIONSingapore's defense against imported novel influenza A (H1N1-2009) comprised public health measures in compliance with the World Health Organization's (WHO) International Health Regulations (IHR), 2005. We report herein on the epidemiology and control of the fi rst 350 cases notified between May and June 2009.

MATERIALS AND METHODSWe investigated the fi rst 350 laboratory-confirmed cases of novel influenza A (H1N1-2009) identified from the healthcare institutions between 27 May and 25 June 2009. Epidemiological details of these cases were retrieved and analysed. Contact tracing and active case finding were also instituted for each reported case, and relevant particulars including flight information were provided to WHO and overseas counterparts.

RESULTSThe fi rst 350 novel influenza A (H1N1-2009) cases comprised 221(63%) imported cases, 124 (35%) locally acquired cases and 5 (2%) cases with unknown source. The imported cases consisted of three waves involving the United States (US), Australia and Southeast Asia. In the fi rst wave, 11 (69%) of the 16 imported cases had visited the US within seven days prior to their onset of illness between 25 May and 4 June 2009. In the second wave, 20 (74%) of the 27 imported cases between 5 June and 12 June had travelled to Melbourne, Australia. In the third wave, 90 (51%) of the 178 imported cases between 13 June and 25 June were acquired from intra-regional travel in Southeast Asia. Specifically, 49 cases were from the Philippines and 40 (82%) of them had travelled to Manila. A total of 667 communications were effected through the IHR mechanism; a majority within 24 hours of disease notification.

CONCLUSIONSingapore experienced an unprecedented need for international cooperation in surveillance and response to this novel Influenza A (H1N1-2009) pandemic. The IHR mechanism served as a useful channel to engage in regional cooperation concerning disease surveillance and data sharing, but requires improvement.

Adolescent ; Adult ; Child ; Disease Notification ; Disease Outbreaks ; prevention & control ; Female ; Guideline Adherence ; Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; prevention & control ; International Cooperation ; Male ; Singapore ; epidemiology ; Travel ; World Health Organization ; Young Adult

INTRODUCTIONThis paper describes the epidemiology and control of a community outbreak of novel influenza A (H1N1-2009) originating from a dance club in Singapore between June and July 2009.

MATERIALS AND METHODSCases of novel influenza A (H1N1-2009) were confirmed using in-house probe-based real-time polymerase chain reaction (PCR). Contact tracing teams from the Singapore Ministry of Health obtained epidemiological information from all cases via telephone.

RESULTSA total of 48 cases were identified in this outbreak, of which 36 (75%) cases were patrons and dance club staff, and 12 (25%) cases were household members and social contacts. Mathematical modelling showed that this outbreak had a reproductive number of 1.9 to 2.1, which was similar to values calculated from outbreaks in naïve populations in other countries.

CONCLUSIONThis transmission risk occurred within an enclosed space with patrons engaged in intimate social activities, suggesting that dance clubs are places conducive for the spread of the virus.

Adolescent ; Adult ; Commerce ; Contact Tracing ; methods ; Dancing ; Disease Outbreaks ; Female ; Humans ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza, Human ; diagnosis ; epidemiology ; Interviews as Topic ; Male ; Models, Statistical ; Polymerase Chain Reaction ; Singapore ; epidemiology ; Travel ; Young Adult