The results of a survey of 223 Peruvian and Colombian monkeys and marmosets for trypanosomes are presented. Eight Trypanosoma cruzi or Trypanosoma cruzi-like infections and 42 infections with trypanosomes identified as Trypanosoma minasense were detected in 47 (21%) of the animals. There were three double infections. Trypanosomes were found in 11 of 14 species, representing eight of nine surveyed primate genera.
Strains of T. cruzi were identified in Peruvian squirrel monkeys (Saimiri boliviensis) and marmosets (Tamarinus nigricollis). Infections in other Peruvian and Colombian squirrel monkeys (S. sciurea) were presumed to be due to T. cruzi. The Tamarinus strain of T. cruzi grew well in culture, developed normally in posterior station in reduviid bugs (Triatoma protracta) and was highly virulent for suckling and immature mice. Previous records for T. cruzi and/or T. cruzi-like trypanosomes in Neotropical lower primates are discussed. T. sanmartini is more likely an aberrant strain of T. cruzi than a distinct species. A presumed arboreal T. cruzi cycle involving primates and unknown arboreal intermediate hosts is discussed.
T. minasense, a T. rangeli-like trypanosome, is apparently common in Neotropical arboreal primates. Saimiri strains of T. minasense grew well in culture, but Saimiri and Cebus strains failed to infect adults and nymphs of Triatoma infestans and T. protracta. A Saimiri strain was non-pathogenic for suckling mice and did not produce tissue forms. The synonymy of the T. rangeli-like trypanosomes is considered, and mechanisms of transmission of trypanosomes between arboreal primates are discussed, with particular reference to T. minasense. Both transmission by ingestion of infected insects and transmission by biting (or biting-plus-defecation) probably take place.
Primates infected with T. cruzi are known to be imported into the United States from the New World tropics. It is unlikely that these trypanosome strains will find their way into native invertebrates and vertebrates, including man, in this country. On the other hand the laboratory investigator should be aware, both from the point of view of his own health and that of his animals, that T. cruzi may occur in these animals.
Present address: Medical Zoology Laboratory, Institute for Medical Research, Kuala Lumpur, Malaya.