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Published Date: 2012-03-01 22:13:06
Subject: PRO/EDR> Hand foot & mouth disease - Singapore
Archive Number: 20120301.1058004

HAND, FOOT AND MOUTH DISEASE - SINGAPORE
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Date: Thu 1 Mar 2012
Source: ST.Breaking News, Singapore [edited]
http://www.straitstimes.com/BreakingNews/Singapore/Story/STIStory_772355.html

Hand, foot and mouth disease (HFMD) cases have hit epidemic levels for the 2nd week running. Nearly 3 times as many youngsters have reported falling ill over the last 2 months compared with the same period last year [2011].

Three childcare centres have also been placed on the Ministry of Health's watch list due to the high number of pupils with the viral infection, which mostly affects children. The symptoms include fever, sore throat, mouth ulcers and blisters on the hands and feet.

[Byline: Poon Chian Hui]

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[The identity of the etiologic agent in the current outbreak has yet to been revealed. The following background information on HFMD in Singapore is reproduced from a recent publication in BMC Infect Dis. 2011; 11: 270. By: Li W Ang, Meng C Phoon, Yan Wu, Jeffery Cutter, Lyn James,and Vincent T Chow, http://www.biomedcentral.com/1471-2334/11/270.

"Enterovirus 71 (EV71) and coxsackievirus A16 (CA16) have caused large epidemics of hand, foot and mouth disease (HFMD) worldwide. Since EV71 was 1st identified in 1969 from an infant suffering from encephalitis in California, outbreaks associated with this virus have been documented, including in Australia in 1972, Japan in 1973 and 1978, Bulgaria in 1975 and Hungary in 1978. EV71 infection is occasionally associated with severe complications (such as encephalitis) and deaths in children. Since 1997, EV71-related HFMD epidemics in the Asia-Pacific region have been increasingly reported, including in Sarawak, Malaysia in 1997, 2000, 2003 and 2006; Brunei in 2006; Perth, Australia in 1999 [11]; Taiwan in 1998 and 2000; Japan in 2000 and 2003; and China in 2008.

"In Singapore, HFMD was 1st recognized in an outbreak in June-July 1970, but the etiologic agent was hitherto unknown. CA16 was associated with 2 other outbreaks without serious complications or fatalities, involving 104 individuals between September 1972 and January 1973, and 742 individuals between September and December 1981. EV71 was 1st isolated from an infant with symptoms of HFMD in Singapore in 1984. Between September and October 2000, a large EV71-associated HFMD outbreak occurred in Singapore, resulting in 4 deaths. HFMD became notifiable under the Infectious Diseases Act from 1 Oct 2000. All preschool centers were closed from 1 Oct to 15 Oct 2000. By 28 Oct 2000, a total of 2827 cases were notified. The main pathologic findings in the fatal cases were encephalitis, interstitial pneumonitis, and myocarditis. Thereafter, EV71-associated HFMD epidemics occurred in 2006 and 2008, with the latter being the largest known HFMD outbreak in Singapore.

"HFMD is endemic in Singapore, and more than 50 percent of cases occur in children below 5 years of age. Although the predominant circulating enteroviruses change periodically, the 2 major enteroviruses causing nationwide HFMD epidemics in Singapore have been CA16 and EV71.

"An EV71 serologic survey in Singapore had been conducted on serum samples collected from 856 children aged 12 years or younger at a pediatric clinic at the National University Hospital (NUH) between July 1996 and December 1997. All children who were born at the hospital or brought for routine visits and vaccinations during this 18-month period were included, and they did not exhibit HFMD-related symptoms at the time of sample collection. Since then, there had not been any comprehensive survey to measure the EV71 seroprevalence between or after EV71-associated HFMD epidemics in Singapore.

"Between August 2008 and July 2010, we conducted a seroprevalence survey to estimate the levels of EV71-specific neutralizing antibodies among children and adolescents aged between 1-17 years. This was the largest and 2nd nationally representative survey conducted to ascertain the latest age-specific seroprevalence of EV71 infection in Singapore. We compared our findings with the results of the 1996-1997 study to discern any significant changes over the past decade.

"Our study revealed that EV71 infection is very common among Singapore children and adolescents, with 39 percent infected by the time they are in secondary school (i.e. 13-17 years of age). The previous 1996-1997 study was conducted before the 1st EV71-associated HFMD epidemic occurred in 2000. Our survey commenced in August 2008, several months after an HFMD epidemic started in Singapore around March 2008. This may have contributed in part to the EV71 seroprevalence found in our survey.

"Around the same period in 2008, there were heightened levels of EV71 activity in the Asia-Pacific region, including Malaysia, mainland China, Hong Kong, and Taiwan [28]. In China, EV71-associated epidemics were documented in many provinces from March to August 2008, with about 490 000 HFMD cases, including 126 fatalities reported in 2008."

"Based on our findings, higher EV71-specific neutralizing antibody titers were observed in pre-school children aged 1-6 years than those in the other 2 older age groups, indicating that most of the infections had been acquired during early childhood. Seroprevalence surveys conducted periodically to measure the prevalence of EV71-neutralizing antibody in the pediatric population in Singapore will facilitate a more in-depth understanding of the epidemiologic trends and HFMD epidemics associated with EV71 infections."

Interested readers are recommended to read the full (open access) paper for a more detailed account of the analysis.

The HealthMap interactive map of Singapore can be accessed at: http://healthmap.org/r/1l5I. - Mod.CP]

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