A total of 687 sera from adults and children in three areas of Trinidad were tested for the presence of neutralizing antibodies against VEE virus. In southwestern Trinidad, the area involved in the 1943–1944 epizootic, antibodies were found only in sera from individuals living in 1944. In the Port of Spain area, evidence of post-1944 experience with the virus was very slight. By contrast, in the non-epizootic area of central Trinidad, an appreciable incidence of serological positivity was found in all age groups, including children born after 1944, some even born as late as 1949. Possible explanations for these last findings are discussed. Of these, the most tenable postulates the existence in this area of a well-established focus of VEE virus, or a closely related strain, which produces essentially symptomless infection in man. Possible origins of this focus are considered.
Colonel, MC, USA (formerly with the U. S. Army Medical Unit, Walter Reed Army Medical Center, Fort Detrick, Maryland).
Staff member, The Rockefeller Foundation (formerly Director, Trinidad Regional Virus Laboratory, Port of Spain, Trinidad, W.I.).