Summary

Serological surveys of Trinidad residents by the Trinidad Regional Virus Laboratory demonstrated yellow fever immunes in eight individuals 15–19 years of age, and in a high proportion of older individuals. Yellow fever virus was isolated from a human case in April 1954. Subsequently virus isolations have been made from 13 other human cases, 7 red howler (Alouatta) monkeys which were brought in dead, 21 pools of Haemagogus mosquitoes, and 1 pool of mixed mosquitoes—a total of 43 virus isolations. Yellow fever virus was repeatedly recovered from Haemagogus mosquitoes captured at ground level.