A Large-Scale Serum-Neutralization Survey of Certain Vertebrates as Part of an Epidemiological Study of Encephalitis of the Western Equine and St. Louis Types

摘要

1. 1. From an irrigated western valley region, where both St. Louis and western equine encephalitis occur in annual epidemics, 576 sera representing 74 species were examined by means of the neutralization-test for antibody against both viruses.2. 2. Each of the viruses was neutralized by approximately 50 per cent of the sera from domestic fowl and to a less extent by sera from domestic mammals. The sera from wild species from each group showed a significantly lower percentage of positives than those from the respective domestic groups. Only 8 per cent of the sera from wild mammals possessed antibodies. No sampling error was found which would alter the significance of these differences.3. 3. From “control” areas, where encephalitis was not recognized, 132 sera, largely from domestic species, were tested. Only one was positive. This confirms the specificity of the neutralization-test.4. 4. In this valley the epidemiology of these two diseases appears to be parallel.5. 5. It is concluded that many of these birds and mammals, principally the domestic fowl, probably serve as reservoirs for infection of mosquitoes. The percentage of susceptible horses which become infected is very high.