Retroperitoneal fibromatosis and acquired immunodeficiency syndrome in macaques: epidemiologic studies

At the University of Washington Regional Primate Research Center, a simian acquired immunodeficiency syndrome (SAIDS) associated with retroperitoneal fibromatosis (RF) has been observed in 82 macaques since 1976, including 77 pigtailed macaques (Macaca nemestrina), two long-tailed macaques (M. fascicularis), one Japanese macaque (M. fuscata) and two rhesus macaques (M. mulatta). The syndrome is characterized by immunodeficiency accompanied by a fibroproliferative lesion, primarily affects young monkeys (1-3 years) and has a high case fatality rate. Based on the occurrence of RF in colony-born and non-colony-born monkeys, the minimum incubation period for natural exposure is believed to be about 9 months. The incidence of RF was 0.9% in M. nemestrina, 0.1% in M. fascicularis, 1.0% in M. fuscata and 0.4% in M. mulatta. There were no significant differences in the incidence of RF by sex or seasonality. Epidemiologic studies were focused on 42 juvenile M. nemestrina that developed RF between January 1980 and June 1983, and the results were compared with 42 age- and sex-matched controls. The incidence of RF was 5.7% in monkeys 12-24 months old and 3.4% in monkeys 24-36 months old, but less than 1.0% in age groups of under 1 year and over 3 years. No significant associations were found for housing history, parentage, generations or ancestral origins. Epidemiologic information and preliminary viral studies suggest a type D retrovirus may be the causative agent in RF and SAIDS. RF associated with SAIDS appears to be an excellent model for Kaposi's sarcoma associated with human AIDS.