抄録
Epidemiological and virological studies of a large epidemic of echo-4 virus meningitis occurring in Japan in 1964 are described. The findings are as follows: (1) Out of about 400 specimens collected in the epidemic areas 152 strains of echo-4 virus were isolated by primary MK tube cultures. The isolation was successful up to day 9 after onset from spinal fluid (28.8% in the first week and 18.2% in the second week), day 16 from stools (61.4% in the first week and 44.1% in the second week), and day 3 from throat swabs. (2) The plaque method was ten times more sensitive than the tube method in echo-4 virus isolation from clinical materials and it afforded another advantage to have allowed quantitative measurement of existing virus in a material. The isolation rate from spinal fluid collected within 10 days after onset reached as high as 86% and that from blood taken within 5 days was 56%. The high rate of occurrence of echo-4 virus in spinal fluid and blood is considered to have significance in the pathogenesis of meningitis. (3) The current echo-4 virus isolated shared antigenic similarity, belonging to the Pesascek type which readily showed break through in neutralization. When compared serologically, they revealed rather unique antigenicity to the past echo-4 virus strains. (4) Human embryonic lung cell tube culture was of utility value for the neutralization of Pesascek type of echo-4 virus, since the endpoint was easily determined without break through. And also it was as useful as MK cells for virus isolation. (5) Seroepidemiological survey revealed that individuals under 9 years of age had no antibody to echo-4 virus before the epidemic in several areas of prevalence, thus it was concluded that the echo-4 virus epidemic broke out after an interval of about ten years. And other epidemiological features are described and disscussed.
