ABSTRACT
Serologic profiles were established using the indirect fluorescent antibody test in a longitudinal study of six villages in an interior area of El Salvador. Positive serologic responses as well as active cases found through the voluntary collaborator posts occurred primarily in adult males, suggesting that much of the malaria experience in the study area resulted from exposure of this segment of the population in more malarious areas where they traveled to engage in temporary agricultural labor. Malaria incidence was generally low but transmission potential apparently varied markedly even over relatively small distances. Serologic profiles reflected the malaria experience in the population sampled, but many localities were widely dispersed and samples taken from village centers were found in some cases not to be representative of the entire locality population in terms of malaria exposure. The indirect fluorescent antibody technique was found to reflect the malaria experience in the population segments examined. When these data were correlated with the surveillance data from the voluntary collaborator posts, the epidemiology of malaria in the study area was more thoroughly understood.