An outbreak of aseptic meningitis due to echovirus 30 in a high school baseball club--possible role of severe exercise for a high attack rate.

In September 2008, an outbreak of aseptic meningitis caused by echovirus 30 occurred in Ota City, Gunma. Among the 26 people hospitalized, 17 were members of a high school baseball club. The attack rate within the club was as high as 40%. The other 9 patients were either their families or close relatives of the baseball club members, indicating the outbreak was confined to a limited community. Although numerous outbreaks of echoviral meningitis have been reported worldwide, those with such a high attack rate within a limited community are rare. Severe physical exercise in a hot temperature could be associated with this high attack rate.