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Published Date: 2012-03-19 20:21:50
Subject: PRO/EDR> Hand, foot & mouth disease (03): Taiwan, EV71
Archive Number: 20120319.1074955

HAND, FOOT AND MOUTH DISEASE (03): TAIWAN, ENTEROVIRUS 71
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Date: Mon 19 Mar 2012
Source: Focus Taiwan News channel [edited]
http://focustaiwan.tw/ShowNews/WebNews_Detail.aspx?Type=aALL&ID=201203190024

Taipei city health authorities warned Monday [19 Mar 2012] of a rising trend of enterovirus (EV) infection and the likelihood that the virus, a common cause of hand, foot and mouth disease [HFMD] among children, will also attack teenagers. Lin Kuo-ning, deputy chief of the city Department of Health's disease control division, said there have been 5 cases of enterovirus 71 (EV71) infection reported so far this year [2012], involving one high school student and 2 junior high school students.

EV71 is a picornavirus associated with HFMD and fatal neurological illness in infants and young children. These cases suggest a rising trend in the age of patients susceptible to EV, Lin said.

According to city health department statistics, as of 10 Mar 2012, district hospitals in the city had reported a total of 1182 cases of EV infection, 2.8 times the 417 cases the hospitals reported in the same period last year [2011]. Meanwhile, schools around Taipei reported a total of 1384 EV[71?] cases from 1 Jan 2012 to 10 Mar 2012, some 3.93 times the 352 cases recorded in the same period of last year. The accumulated number of school classes forced to be suspended due to cluster infections reached 113 classes during this period, that is 3.22 times the 35 classes reported in the same period of 2011, the statistics show.

The city health department reminded the public that infants and toddlers aged under 5 are at the highest risk of severe EV infection. Children who develop symptoms of extreme sleepiness, unconsciousness, vomiting, persistent fever or seizures should be taken to local clinics or hospitals for medical treatment as soon as possible, the department said.

[Byline: Huang Li-yun and Elizabeth Hsu]

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[It seems likely that EV71 is the virus mainly responsible for the current outbreaks in Southeast and South Asia, although the causative agent is rarely specified.

EV71 was 1st identified in 1969 from an infant suffering from encephalitis in California, and subsequent outbreaks associated with this virus have been described, 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; China in 2008, and currently in Viet Nam.

EV71 phylogenetic analyses have revealed considerable genetic diversity. VP1 sequences [indicative of potential antigenic diversity] clustered into 3 genogroups, A, B and C, with genogroups B and C further divided into 5 subgenogroups, B1-B5 and C1-C5, respectively. All EV71 strains were clustered similarly in the 5'UTR and VP1 trees, except for one Taiwanese strain, which demonstrated different clustering in the 2 trees, suggesting a recombination event in the phylogeny.

Another recent overview describes the molecular epidemiology of human enterovirus 71 (HEV71) in the Asia-Pacific region from 1997 through 2002. Phylogenetic analysis of the VP4 and VP1 genes of recent HEV71 strains indicates that several genogroups of the virus have been circulating in the Asia-Pacific region since 1997. The 1st of these recent outbreaks, described in Sarawak (Malaysian Borneo) in 1997, was caused by genogroup B3. This outbreak was followed by large outbreaks in Taiwan in 1998, caused by genogroup C2, and in Perth (Western Australia) in 1999, where viruses belonging to genogroups B3 and C2 co-circulated. Singapore, Taiwan, and Sarawak had HEV71 epidemics in 2000, caused predominantly by viruses belonging to genogroup B4; however, large numbers of fatalities were observed only in Taiwan. HEV71 was identified during an epidemic of hand, foot and mouth disease in Korea; that epidemic was found to be due to viruses constituting a new genogroup, C3.

See:
[1] J Gen Virol. 2010 Aug;91(Pt 8):1949-58. Epub 2010 Apr 7. Evolutionary trajectory of the VP1 gene of human enterovirus 71 genogroup B and C viruses. van der Sanden S, van der Avoort H, Lemey P, Uslu G, Koopmans M.

[2] J Virol. 2012 Mar;86(5):2676-85. Epub 2011 Dec 28. The association of recombination events in the founding and emergence of subgenogroup evolutionary lineages of human enterovirus 71. McWilliam Leitch EC, Cabrerizo M, Cardosa J, Harvala H, Ivanova OE, Koike S, Kroes AC, Lukashev A, Perera D, Roivainen M, Susi P, Trallero G, Evans DJ, Simmonds P.

It would be of interest to establish the genogroup of the virus responsible for the current outbreak in Taiwan.

A map of Taiwan, showing Taipei in the north, can be accessed at: http://www.lib.utexas.edu/maps/middle_east_and_asia/taiwan_pol92.jpg. - Mod.CP

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/r/1ob5.]

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