Echovirus type 9 epidemic in Kagoshima, southern Japan: seroepidemiology and clinical observation of aseptic meningitis.

An outbreak of aseptic meningitis caused by echovirus type 9 occurred between March and October, 1990, in Kagoshima, Southern Japan. Clinical manifestations and laboratory data of 259 children with aseptic meningitis who were admitted to the outpatient clinic of pediatrics in the Kagoshima City Hospital were analyzed (other diseases caused by echovirus type 9 were not investigated). The patients' age ranged from 1 month to 15 years and the highest incidence was in 4-year-old children. The male:female ratio was 1.3:1. Frequencies of headache (69%), vomiting (64%), neck stiffness (36%) and rash (195%) were lower than those in the previous reports in the United States or in the Europe. Pleocytosis in the cerebrospinal fluid increased with increasing age in the younger children. A predominance of neutrophils in cerebrospinal fluid lasted for 3 days or more after onset in 16% of the patients. Seroepidemiologic study suggested that the accumulation of susceptible children < 5 years of age had predisposed to the epidemic.