| Abstract: | A large epidemic of aseptic meningitis due to ECHO 6 virus swept over Japan in the summer months of 1965. In our studies on 89 cases of aseptic meningitis in the epidemic, primary culture of human embryonic kidney cells was shown to provide a highly sensitive host system for isolation of ECHO 6 virus from clinical materials. Virus was recovered from cerebrospinal fluid in 72% of 89 cases, from throat swabs in 64% of 36 cases, and from rectal swabs in 59% of 37 cases. Most significant is the finding that the rate of virus isolation from cerebrospinal fluid in this host system was considerably higher as compared with that obtained by other investigators in other host systems such as primary monkey kidney cells or human amniotic cells (primary or EL). This finding should be emphasized particularly because isolation of a virus from cerebrospinal fluid, in contrast to throat secretions or feces, is of much greater importance in establishing the etiologic relationship to the disease in the diagnosis of aseptic meningitis. The neutralization test was shown to be efficient in detecting ECHO 6 virus infection; acute serums should be taken preferably by the 4th day of illness and convalescent serums in the second week. Epidemiologic findings, such as the predominance of male patients and occurrence of the epidemic in summer months, generally coincide with the previous reports. However, our cases were in much younger age groups in contrast with the previous reports; 90% of our 89 patients were 6 years of age or younger, and 15 children or 17% were less than 1 year of age, including 3 less than 6 months of age. The clinical observations on our cases confirmed the previous reports. |
