Pandemic (H1N1) 2009 Surveillance and Prevalence of Seasonal Influenza, Singapore

DOI: 10.3201/eid1601.091164
Suggested citation for this article: Leo Y-S, Lye DC, Barkham T, Krishnan P, Seow E, Chow A. Pandemic (H1N1) 2009 surveillance and prevalence of seasonal influenza, Singapore. Emerg Infect Dis. 2010 Jan; [Epub ahead of print]

Pandemic (H1N1) 2009 Surveillance and Prevalence of Seasonal Influenza, Singapore
Yee-Sin Leo, David C Lye, Timothy Barkham, Prabha Krishnan, Eillyne Seow, and Angela Chow

Author affiliation: Tan Tock Seng Hospital, Singapore

On April 25, 2009, Singapore implemented strict containment measures for pandemic (H1N1) 2009 with enhanced surveillance and hospital isolation. In the first month, seasonal influenza, predominantly virus subtype H3N2, was diagnosed for 32% of patients with acute febrile respiratory illness. Our findings underscore the high prevalence of seasonal influenza in Singapore.

Tropical countries experience influenza year round, with 2 peaks corresponding to the rainy seasons (1). Despite this year-round activity, seasonal influenza is often neglected in tropical countries in terms of clinical diagnosis, treatment, and vaccination (2). In Singapore, influenza activity usually peaks in June and December (3). The annual all-cause death rate from seasonal influenza in Singapore has been estimated at 14.8/100,000 person-years; the proportion of deaths among persons ≥65 years of age is 11.3× higher than that among the general population (4). In addition, previous pandemic influenza–related excess deaths in Singapore are comparable to those in temperate countries (5).

In April 2009, a novel influenza A virus (H1N1) of swine origin emerged in the United States (6) and triggered alarm about its pandemic potential (7). On June 11, 2009, the World Health Organization announced that the virus had become pandemic; it is now referred to as pandemic (H1N1) 2009 virus (8). We report on enhanced influenza surveillance in Singapore...

abrir aquí para acceder al documento CDC EID completo en pdf de 7 páginas:
http://www.cdc.gov/eid/content/16/1/pdfs/09-1164.pdf