EV-71

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Enterovirus 71 (EV71) EV71 was first isolated and characterized from cases of neurological disease in California in 1969.[1][2] "Enterovirus 71 (EV71), the newest member of Enterovirudae, is notable for its etiological role in epidemics of severe neurological diseases in children. It appears to be emerging as an important virulent neurotropic enterovirus in the upcoming era of poliomyelitis eradication".[3] The illness usually peaks in June or July.

"Enterovirus 71 (EV71) infection may be asymptomatic or may cause diarrhea, rashes, and hand, foot and mouth disease (HFMD). However, EV71 also has the potential to cause severe neurological disease. To date, little is known about the molecular mechanisms of host response to EV71 infection. [...] EV71 infection led to increases in the level of mRNAs encoding chemokines, proteins involved in protein degradation, complement proteins, and proapoptotis proteins."[4]

"Enterovirus 71 (EV71), one of the major causative agents for hand, foot and mouth disease (HFMD), is sometimes associated with severe central nervous system diseases. In 1997, in Malaysia and Japan, and in 1998 in Taiwan, there were HFMD epidemics involving sudden deaths among young children, and EV71 was isolated from the HFMD patients, including the fatal cases. The nucleotide sequences of each EV71 isolate were determined and compared by phylogenetical analysis. EV71 strains from previously reported epidemics belonged to genotype A-1, while those from recent epidemics could be divided into two genotypes, A-2 and B."[5]

"Ever since the 1980s, large and small EV71 epidemics caused by distinct genotypes have occurred in Asian countries and regions sharing trade with China. In Hong Kong, sporadic EV71 infections with incidences of monoplegia were reported in 1987, and a fatal case was documented in 2001. A large outbreak of HFMD due to EV71 infection occurred in Taiwan in 1998, including 129,106 case reports, 405 children with severe complications, and more than 80 deaths. After 1998, smaller EV71 epidemics occurred almost annually in Taiwan, primarily associated with EV71 viruses of genotypes C2 and B4. In Malaysia, EV71 outbreaks occurred in 1997 and 2000, mainly associated with genotypes B3 and B4. Since 1997, EV71 epidemics (genotypes B and C) have been reported annually in Singapore, with genotype B4 forming the predominant causative agent of a large outbreak in 2000 (5). In Korea, an EV71 epidemic in 2000 was caused by a relatively new genotype, C3, which has only rarely been identified outside of Korea in recent years (10). Thus, the EV71 genotypes of these HFMD epidemics seem to be regionally and temporally unrestricted."[6]

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[edit] Treatment

There is no vaccine or antiviral agent known to be effective in treating or preventing EV71 infection. Experimental vaccines and antiviral agents are being worked on.[7] For example, "both bovine and human lactoferrins were found to be potent inhibitors of EV71 infection"[3] and "ribavirin could be a potential anti-EV71 drug."[8]

[edit] Taiwan

"Two outbreaks of hand-foot-and-mouth disease (HFMD) occurred in Taiwan between 1998 and 2000. Enteroviruses were isolated from a total of 1,892 patients in this laboratory during this period. Of the virus isolates, enterovirus 71 (EV71) was diagnosed in 44.4% of the patients (132 of 297) in 1998, 2% (13 of 646) in 1999, and 20.5% (195 of 949) in 2000. Genetic analyses of the 5�-untranslated and VP1 regions of EV71 isolates by reverse transcription-PCR and sequencing were performed to understand the diversity of EV71 in these outbreaks of HFMD. Most EV71 isolates from the 1998 epidemic belonged to genotype C, while only one-tenth of the isolates were genotype B. Interestingly, all EV71 isolates tested from 1999 to 2000 belonged to genotype B. This study indicated that two genogroups of EV71 capable of inducing severe clinical illness have been circulating in Taiwan. Furthermore, the predominant EV71 genotypes responsible for each of the two major HFMD outbreaks within the 3-year period in Taiwan were different."[1]

[edit] China

From 1999 to 2004, there were no epidemics of hand, foot, and mouth disease in Shenzhen, People's Republic of China, but each year there were small, local outbreaks associated with only a few cases of neurological disease and no reported fatalities. Genetic analysis revealed 19 cases of EV71 among 147 children who had hand, foot, and mouth disease in Shenzhen during this time.[6]

Until 2008, no large EV71 epidemic had been reported on the Chinese mainland, but sporadic infections were common in the southeast coastal area as well as inland regions, such as Beijing, Chongqing, and Jinan. From 1998 to 2004, the only EV71 viruses identified on mainland China belonged to the genotype C4, indicating far less variety in China than in Taiwan.[6]

On May 3, 2008, Chinese health authorities reported a major outbreak of EV71 enterovirus in Fuyang city and other localities in Anhui, Zhejiang, and Guangdong provinces. As of May 3, 2008, 3736 cases occurring mainly in children have been reported, with 22 dead and 42 critically ill. Some 415 new cases have been reported in the last 24 hours in Fuyang City alone.[9][10] As of May 5, 2008, 6,300 were sickened by the viral outbreak which killed another child, in Zhejiang raising the death toll to 26 children, with 1,198 other children affected in that province alone. Specifically, an additional 5,151 cases were reported in Anhui province with scores more in 4 other provinces. 8,531 cases of children infected with hand-foot-mouth disease (HFMD) were reported in China. All the children infected are aged below 6, with most of them being under 2.[11][12][13] As of May 7 contagious HFMD led to 28 deaths.[14] Xinhua reported the number of people infected, also rose by 4000 to 15,799.[15]

[edit] Vietnam

Vietnam has recorded some 2,000 cases of hand, foot and mouth disease in the first four months of this year, said Nguyen Huy Nga, director of the Ministry of Health's Department of Preventive Medicine. Between 10 and 20 percent were caused by EV71.[16]

[edit] Sources and notes

  1. ^ a b Change of Major Genotype of Enterovirus 71 in Outbreaks of Hand-Foot-and-Mouth Disease in Taiwan between 1998 and 2000
  2. ^ Laboratory Investigation of a Suspected Enterovirus 71 Outbreak
  3. ^ a b Lactoferrin Inhibits Enterovirus 71 Infection of Human Embryonal Rhabdomyosarcoma Cells In Vitro
  4. ^ Identification of genes involved in the host response to enterovirus 71 infection J Neurovirol. 2004 Oct;10(5):293-304
  5. ^ Enterovirus 71 from fatal and nonfatal cases of hand, foot and mouth disease epidemics in Malaysia, Japan and Taiwan in 1997-1998 Jpn J Infect Dis. 1999 Feb;52(1):12-5.
  6. ^ a b c 1
  7. ^ DNA vaccine constructs against enterovirus 71 elicit immune response in mice
  8. ^ Ribavirin Reduces Mortality in Enterovirus 71–Infected Mice by Decreasing Viral Replication
  9. ^ China on alert as virus spreads BBC News
  10. ^ China orders heightened efforts to stop deadly virus AP News
  11. ^ news.bbc.co.uk, China virus toll continues rise
  12. ^ www.inthenews.co.uk, Hand-foot-mouth epidemic continues to infect children across China
  13. ^ ap.google.com, China says 6,300 cases in viral outbreak
  14. ^ news.xinhuanet.com, Xinhua's tally: Death toll of hand-foot-mouth disease rises to 28 in China
  15. ^ www.theaustralian.news.com.au, 28 Chinese children die from virus
  16. ^ http://news.yahoo.com/s/ap/20080507/ap_on_he_me/china_child_virus