Abstract
Serologic testing revealed that 17/84 (20·2%) of bought-in Aotus and 1/31 (3·2%) of colony-born Aotus had haemagglutination-inhibition antibody. Clinically-inapparent measles infections were detected in 3 monkeys by increased antibody titres. Following the detection of a recent infection, antibody titre persisted at a high level for at least 240 days. Although 84% of the monkeys were sero-susceptible, no further serological evidence of measles infection occurred.