奈良県におけるエンテロウイルスによる無菌性髄膜炎の疫学的研究

Abstract

In order to characterize epidemiologic features of aseptic meningitis in Nara Prefecture, Japan, the temporal and geographic patterns of the most common type of enterovirus were analyzed on the basis of the surveillance data on viral infections for a 12 -year period from 1984 to 1995. The results of the investigation are as follows. 1) Viruses were isolated from 296 among 749 patients with aseptic meningitis over the entire 12-year period. Enteroviruses were found in 262 patients, and accounted for 88.5% of the virus isolated cases. The incidence of enteroviral meningitis was high in summer with a peak in July in these years. The numbers and the major serotypes of isolated enterovir- uses varied from year to year. 2) Enteroviral meningitis was provoked more frequently with two peaks of age-specific incidence (one at less than one year, and the second at 5 years of age) and was 1.8 times more frequent in males than in females. 3) More prevalent types of the enteroviruses which caused aseptic meningitis had two spreading patterns : one had an epidemic provably every 3-4 years (echovirus type 6, 7 and 30), the other appeared sporadically every year (coxsakievirus A4, A16, B3 and B5 and echovirus type 25). 4) Echovirus type 30 was isolated less frequently in the northern area of Nara Prefecture, which seemed to be due to interference with other enteroviruses. The present analyses may suggest the possibility of prediction of the enterovirus epidemic type in the coming years with data on virus isolates in the preceding years.