Abstract
An outbreak of acute respiratory disease was observed in a colony of marmosets (Callithrix jacchus). Parainfluenza Type I (Sendai) virus was isolated from the lungs and from throat swabs of 2 animals which showed clinical signs of disease. A rising titre of serum neutralizing antibody to the virus isolated was detected in several affected animals. Approximately 50% of the colony showed clinical signs of disease, and 3 animals died. The duration of illness ranged from 3 to 16 days.