Blood samples obtained from indigenous residents of 38 localities in 6 states in India have been tested for neutralizing antibody against each of 15 different viruses known or believed to be arthropod borne.
All tests with yellow fever, Bwamba fever, and Bunyamwera viruses were negative. A small number of sera were found which neutralized Ilhéus or Semliki Forest viruses, but neither of these agents appears to be of much importance in the localities sampled.
Six of 211 sera neutralized St. Louis encephalitis virus. The same sera also neutralized West Nile virus. The interpretation of this result is not attempted.
Antibodies against dengue types 1 and 2 and West Nile viruses were found in sera from residents of many localities; in some localities the incidence of protection was quite high. Significant numbers of the sera neutralized Zika, Uganda S, Nitaya, Japanese B, or Murray Valley virus. Six of 26 sera from donors living in the Sorath district of Saurashtra were protective against Russian spring-summer encephalitis virus.
The question of possible group-specific reactions is discussed.