Ecologic Studies of Japanese Encephalitis Virus in Japan

IX. Epidemiologic Correlations and Conclusions

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  • Department of Virus and Rickettsial Diseases, 406th Medical General Laboratory, U. S. Army, Japan
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Study of the ecology of Japanese encephalitis (JE) virus in several habitats near Tokyo between 1952 and 1955 established that infections of the vector mosquito, C. tritaeniorhynchus, the wild avian and porcine amplifying hosts, and the diseased host, man, were annual late summer phenomena. As the study progressed, it was postulated that infections of these hosts were ecologically related, for they occurred almost simultaneously (mosquitoes, birds and pigs) or after a 2-week interval (man) (Articles II, IV, VI and VII). Further, the titers and duration of viremia in laboratory infected birds were adequate to infect 47 to 93% of colonized C. tritaeniorhynchus and, after extrinsic incubation of 15 or more days, 43 to 92% of infected mosquitoes would transmit to birds and pigs. The quantitative dynamics of mosquito-bird-swine infections, and their epidemologic significance to human infections, however, required further study.