Encuesta serológica de virus transmitidos por artrópodos

Abstract

This report deals with the results of a serological survey performed at the "Colonia Penal Agrícola de Araracuara", Colombia, during March, 1966. A total of 396 sera, from persons never vaccinated before against yellow fever, was studied; 262 of them were brought to the area when older than fourteen years of age, and 134 were Indians, natives from that region who had never left it and who live a nomadic existence collecting natural rubber

The rate of people with neutralizing antibodies against yellow fever was high (47.7 per cent) particularly among natives with a rate of 67.8 per cent; non-natives reached 37.4 per cent

The general immunity rates in the hemagglutination-inhibition (HI) test for other agents were: Mayaro, 19.4 per cent; Ilheus, 19.9 per cent, and St. Louis, 18.7 per cent. There also showed higher values among Indians. In each case the incidence follows and endemic pattern without differences between sexes

Ilheus virus was isolated from a person. Venezuelan equine encephalitis (VEE) virus apparently is not present in the area as the Indians had not antibodies and only 4.6 per cent of non-natives had neutralizing antibodies. The St. Louis results -6 per cent neutralization test positivity- are also discussed

As for Mayaro (and/or Una), it seems to be constantly active, with an immunity rate of 44 per cent in the HI test for Indians, and 6.5 per cent for non-natives(AU)