Chagas Disease in 2 Geriatric Rhesus Macaques (Macaca mulatta) Housed in the Pacific Northwest

Chagas disease (American trypanosomiasis) is caused by the protozoan parasite Trypanosoma cruzi. It is endemic in Latin America but also is found in the southern United States, particularly Texas and along the Gulf Coast. Typical clinical manifestations of Chagas disease are not well-characterized in rhesus macaques, but conduction abnormalities, myocarditis, and encephalitis and megaesophagus have been described. Here we report 2 cases of Chagas disease in rhesus macaques housed in the northwestern United States. The first case involved a geriatric male macaque with cardiomegaly, diagnosed as dilated cardiomyopathy on ultrasonographic examination. Postmortem findings included myocarditis as well as ganglioneuritis in the esophagus, stomach, and colon. The second case affected a geriatric female macaque experimentally infected with SIV. She was euthanized for a protocol-related time point. Microscopic examination revealed chronic myocarditis with amastigotes present in the cardiomyocytes, ganglioneuritis, and opportunistic infections attributed to her immunocompromised status. Banked serum samples from both macaques had positive titers for T. cruzi. T. cruzi DNA was amplified by conventional PCR from multiple tissues from both animals. Review of their histories revealed that both animals had been obtained from facilities in South Texas more than 12 y earlier. Given the long period of clinical latency, Chagas disease may be more prevalent in rhesus macaques than typically has been reported. T. cruzi infection should be considered for animals with unexplained cardiac or gastrointestinal pathology and that originated from areas known to have a high risk for disease transmission.Abbreviations: DCM, dilated cardiomyopathy; CMV, cytomegalovirus; NHP, nonhuman primateChagas disease is caused by the hemoflagellate protozoan parasite Trypanosoma cruzi. The disease is endemic in many regions of South and Central America, and its range extends to the southern United States. In the United States, there is evidence that the parasite has established a domestic transmission cycle with canine reservoirs,¹⁹ and there are numerous wildlife reservoirs, most importantly armadillos, raccoons, rodents, and opossums.⁶ The main mode of transmission is via arthropod vectors, primarily triatomine species (kissing bugs or cone-nosed bugs), which serve as intermediate hosts. Vector species are present in the southern half of the United States.² Infection has been reported sporadically in domestic nonhuman primate (NHP) colonies.¹² Autochthonous insect vector-mediated transmission in humans in the United States has been reported rarely.³³ Transmission of T. cruzi to NHP is thought to occur mainly through insect vectors, specifically by contamination of the oral mucous membranes with parasite-containing feces during consumption of the bug. The infection may remain subclinical for years and, similar to that in people, affects the nervous system, digestive system, and heart. Clinical findings in NHP are infrequent but can include subcutaneous edema, fever, anorexia, lethargy, heart failure, and sudden death.^4,5 As in humans, the disease in NHP consists of an acute phase, with a paucity of clinical manifestations, and a chronic phase, characterized by irreversible cardiomyopathy leading to cardiac dysfunction and death. Chronically infected NHP in the indeterminate form of the chronic phase can exhibit subclinical conduction and echocardiographic abnormalities.⁸T. cruzi infections have been reported in a number of NHP species housed in Texas, Louisiana, and Georgia. Species affected include rhesus macaques (Macaca mulatta),^12,17 cynomolgus macaques (M. fascicularis),^29,42 yellow baboons (Papio cynocephalus), olive baboons (P. anubis),^12,14,41 pig-tailed macaques (M. nemestrina),^12,35 squirrel monkeys (Saimiri sciureus),¹³ ring-tailed lemurs (Lemur catta),^15,30 black-eyed lemurs (Eulemur macaco flavifrons), black and white ruffed lemurs (Varecia variegata variegate),¹⁵ pileated gibbon (Hylobates pileatus),³⁶ a lion-tailed macaque (M. silenus),³⁰ a Celebes crested black macaque (M. nigra),²⁷ and a chimpanzee (Pan troglodytes).⁴ Here we report on 2 cases of Chagas disease in rhesus macaques housed in the northwestern United States but that originated from South Texas.