Trypanosomes and microfilariae in feral owl and squirrel monkeys maintained in research colonies

A group of 358 owl and squirrel monkeys imported from Colombia, Peru, and Bolivia for the U.S. Agency for International Development Malaria Vaccine Development Program was examined for trypanosomes and microfilariae. Trypanosoma rangeli, isolated by hemoculture from Aotus nancymai, Saimiri b. boliviensis, and S. b. peruviensis, accounted for 76.6% of all trypanosome infections. Trypanosoma cruzi was isolated from 25 of 194 S. b. boliviensis, including two mixed infections with T. rangeli. Identifications of trypanosomes were confirmed by blinded tests with a panel of five rRNA probes on a subsample of cultures identified morphologically. Although no trypanosomes were isolated from Aotus vociferans or A. lemurinus griseimembra, positive serologic responses to T. cruzi were observed by indirect immunofluorescence assay in all species of monkeys examined and ranged from 42.1% among S. b. peruviensis to 92.3% among A. vociferans. Among T. rangeli-infected monkeys, 43.7% were seronegative for T. cruzi. No microfilariae were found in S. b. boliviensis or A. l. griseimembra. Mansonella barbascalensis and Dipetalonema caudispina were observed in A. vociferans, M. panamensis in A. nancymai, and M. saimiri and D. caudispina in S. b. peruviensis. Such naturally occurring infections in imported animal models are potential sources of accidental transmission to animal handlers and uninfected laboratory animals and can introduce confounding variables into otherwise well-planned and well-executed studies.