Cybermed Update October 2000
There has been a recent increase in Enterovirus cases in the region. First in Singapore, followed by Malaysia and now recently in Philippines and Sri Lanka. A recent posting in Promed has shown an uptrend in the number of reported HFM cases in the country over the last few years, more so when it became compulsory to notify such cases in the day care centers. This uptrend is not only reflective of the incidence in Singapore but I am sure of Malaysia and the region.
In the recent outbreak in Singapore more than 2000 cases of HFM has been reported in the island. The cases were attributed to the similar virus which hit this region in 1997, Enterovirus 71 . The outbreak spilled over to Johore (http://www.thestar.com.my/news/story.asp?file=/2000/10/11/focus/1122cont&newspage=Search), Malaysia with sporadic cases being reported in other States.
The outbreak in Malaysia, was attributed to several enteroviruses, with the fatal and severe cases being due to echovirus 7. I append part of Prof. Lam S.K posting in Promed. "During the present hand, foot and mouth outbreak, several enteroviruses have been isolated by UHKL. These included 7 Coxsackie A16, 14 enterovirus 71, one Coxsackie B, 12 herpes simplex and 6 echo 7. However, 5 of the 6 echo 7 virus isolates were from severe and fatal encephalitis. The identification of echo 7 in severe and fatal cases during an outbreak of HFMD in Malaysia is of global interest because of the increase in emerging and re-emerging diseases worldwide."
Are we seeing an uptrend in new and emerging viruses or is it because of increase in awareness, surveillance and laboratory detection of such cases? This question can only be answered if we have proper records with the setting up of sentinels sites to monitor the disease. This is being done in Taiwan , Japan and Singapore since the Taiwan outbreak.
What are enteroviruses? From Harissons Online,
Enteroviruses are so named because of their ability to multiply in the gastrointestinal tract. Despite their name, these viruses are not a prominent cause of gastroenteritis. Members of the picornavirus (Spanish pico, "a little bit" + RNA + virus) family, enteroviruses encompass 67 human serotypes: 3 serotypes of poliovirus, 23 serotypes of coxsackievirus A, 6 serotypes of coxsackievirus B, 31 serotypes of echovirus, and enteroviruses 68 through 71.
Enteroviruses have no lipid envelope and are stable in acidic environments, including the stomach. These viruses are resistant to inactivation by standard disinfectants (e.g., alcohol, detergents) and can persist for days at room temperature.
An estimated 5 to 10 million cases of symptomatic enterovirus disease occur in the United States each year. Enteroviruses are the major cause of aseptic meningitis and nonspecific febrile illnesses of neonates. Certain clinical syndromes are more likely to be caused by certain serotypes (Table 195-2), but there is much overlap. From 1970 to 1983, 70 percent of enterovirus infections were caused by only 10 of the 67 human serotypes. Echoviruses 9 and 11 alone accounted for 24 percent of recognized enterovirus infections; echoviruses 4, 6, and 30 and coxsackieviruses A9 and B2 through B5 accounted for 46 percent.
Manifestations Commonly Associated With Enterovirus Serotypes
Serotype(s) of Indicated Virus Manifestation Coxsackievirus Echovirus (E) and Enterovirus (Ent) Aseptic meningitis A2, 4, 7, 9, 10; B1-5 E4, 6, 7, 9, 11, 16, 18, 30, 33; Ent70, 71 Exanthem A4, 5, 9, 10, 16; B1, 3-5 E4-7, 9, 11, 16-19, 25, 30; Ent71 Generalized disease of the newborn B2-5 E4-6, 9, 11, 14, 16, 19 Hand-foot-and-mouth disease A5, 7, 9, 10, 16; B2, 5 Ent71 Herpangina A1-10, 16, 22; B1-5 E6, 9, 11, 16, 17, 22, 25 Myocarditis, pericarditis A4, 9, 16; B1-5 E6, 9, 11, 22 Paralysis A4, 7, 9; B1-5 E2, 4, 6, 9, 11, 30; Ent70, 71 Pleurodynia A1, 2, 4, 6, 9, 10, 16; B1-6 E1-3, 69, 11, 12, 14, 16, 19, 2325, 30 Pneumonia A9, 16; B1-5 E6, 7, 9, 11, 12, 19, 20, 30; Ent68, 71
Enteroviruses known to cause Hand-foot-and-mouth disease (HFM) are Coxsackievirus A5,7,9,10,16; B2, 5 and Enterovirus 71. Echovirus 7 on the other hand manifest as Aseptic meningitis, exanthem, pleurodynia and pneumonia. It will be interesting to know what signs and symptoms 5 of the 6 severe/fatal cases echovirus 7 patients had. This is important because clinical presentation of HFM may be absent in these group. (according to Harisson's Online). EV 71 on the other hand may manifest with Aseptic meningitis, exanthem, HFM, paralysis, and pneumonia. Whatever the type of enterovirus, EV 71 or echovirus 7, management is supportive. There are no known proven drugs or vaccine for this disease.
Another interesting observation is the predominent number of EV71 cases in both Malaysia and Singapore but the fatal/serious cases in each country being different.
We may have to consider changing the term HFM cases to Enterovirus cases to encompass the echovirus group. I have used the term "outbreak" loosely for want of a better word.
With that I let your "mouse" or your "keyboard" do the "talking".
Till next month, "Happy Surfing".
Cyberdoc ( firstname.lastname@example.org )
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Updated 15 January 2006.
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