Printed in U.S.A. EPIDEMIOLOGIC INVESTIGATIONS OF THE 1969 EPIDEMIC OF

An epizoodemic of Venezuelan equine encephalitis (VEE), subtype I variant B, occurred in Ecuador during the rainy and hot season of 1969. In this paper, a general description of the epidemic is given and virus isola-tions from humans are reported. A serologic survey was performed in order to determine the extension of the epidemic along the coastal zone of the country. It is not clear whether the higher antibody rate in older people was because they were at greater risk of infection or was the result of an ac-cumulated immunity with time. The latter could be an indication of endemic virus activity, not yet proven for the VEE IB virus variant. Mosquito surveil-lance and attempted control by aerial spraying were carried out. antibodies; encephalitis virus, Venezuelan equine; epidemics; epidemiol-ogy; mosquito control; serolog