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December 18, 1943


JAMA. 1943;123(16):1048-1049. doi:10.1001/jama.1943.02840510042010

Successful laboratory transmission of St. Louis encephalitis virus by several species of mosquitoes has been accomplished by Hammon and Reeves,1 of the Hooper Foundation, University of California. They have demonstrated also a symptom free viral septicemia in domestic fowls as an essential prerequisite for transmission by the mosquito.

During the summer of 1941 a study was made of the possible role of arthropods in the annually recurring epidemics and epizootics of encephalitis in the Yakima Valley, Washington.2 About 50 human cases and an equal number of equine cases occur each year in this valley. Over 15,000 living arthropods were collected and identified in this survey. These included 12,500 mosquitoes of four different genera and about 3,000 domestic flies, black flies, ticks, mites, gnats, horse and deer flies, bedbugs and other insects. These were immediately frozen and transported by air express to the central laboratory in San Francisco. Pools