Enterovirus 71 Outbreaks, Taiwan: Occurrence and Recognition
Enterovirus 71 (EV71) caused a large outbreak in Taiwan in 1998 with 78 deaths, and smaller outbreaks recurred in 2000 and 2001. The outbreak was recognized because of a large number of hand, foot, and mouth disease cases and the rapid deaths of children with the disease. Virologic and pathologic studies indicated that EV71 was the most important agent related to severe and fatal cases and that a neurogenic inflammatory response was involved in the pathogenesis of cardiopulmonary collapse resulting from fulminant EV71 infection. Seroepidemiologic study suggested that EV71 had circulated for at least 16 years and that the accumulation of susceptible hosts might have triggered the 1998 outbreak. However, a change in EV71 neurovirulence and host genetic susceptibility may also have affected the clinical outcome. The Taiwan outbreak shows that worldwide attention should be paid to such outbreaks, new antiviral drugs should be developed, and that vaccination of children under 5 years of age may be warranted.

Enteroviruses consist of 68 serotypes and usually cause self-limited infections in children. Enterovirus 71 (EV71) was first isolated in California in 1969. Since then, EV71 has been isolated in many parts of the world. Two patterns of EV71 outbreaks have been observed: small outbreaks associated with occasional patient death and severe outbreaks associated with a high case-fatality rate. The latter pattern occurred in Bulgaria in 1975 with 44 deaths and Hungary in 1978 with 45 deaths. During the past 5 years severe outbreaks have occurred: in Malaysia in 1997 with 30 deaths and in Taiwan with 78 deaths in 1998, 25 deaths in 2000, and 26 deaths in 2001.