Epidemiologic aspects of an outbreak of acquired immunodeficiency in rhesus monkeys (Macaca mulatta).

Since August 25, 1981, an outbreak of simian acquired immunodeficiency syndrome ( SAIDS ) has been recognized in a single outdoor corral housing 77 rhesus monkeys (Macaca mulatta) over a 16-month period. The etiology of this syndrome is unknown but epidemiologic evidence suggests an infectious agent. Thirty-two cases of SAIDS have been identified (31 female, 1 male), and 27 of these animals have died (case fatality rate = 84%). Three of these deaths occurred among 13 infants born in the corral . All 27 deaths were females. For animals in the original cohort, sex was not a statistically significant risk factor. For animals born in the corral females were at greater risk (p = 0.0489; Fisher's Exact Test). SAIDS mortality rates were highest for animals entering the corral at less than 30 months of age (4.4 deaths per 100 monkey months of follow-up) and for animals born into the cage (3.3 deaths per 100 monkey-months of follow-up). The mortality rate was lowest for animals entering the corral at greater than 30 months of age, (0.32 deaths per 100 monkey-months of follow-up). No significant associations were found for the factors weaning history, cage-move history, parentage, generation, and medical history, including history of bite-wound trauma. Nine of the original 64 animals entering the corral on August 25, 1981, were previously associated with a group of 110 rhesus monkeys occupying this same corral from September 1976 to August 1981. Though less dramatic, a similar pattern of morbidity and high mortality was recognized retrospectively in this group.(ABSTRACT TRUNCATED AT 250 WORDS)