Virological and epidemiological studies on an outbreak of aseptic meningitis caused by echovirus 4 in northern Japan in 1964

During the summer and autumn of 1964, echovirus 4 was found widely distributed in northern Japan; this virus was associated with localized outbreaks of iaseptic meningitis in many regions. The evidence that the echovirus was aetio-logically related to aseptic meningitis was shown by the virus isolation from cerebrospinal fluids and faeces and the serodiagnosis of paired sera in many patients: Age-specific sero-immunity and morbidity rate suggested that echovirus 4 had spread extensively in about 1954. The strains of echovirus 4 isolated in the 1964; epidemic were similar to the prototype strain, Pesascek, in biological characteristics.