Trypanosoma cruzi and Chagas' Disease in the United States

Abstract

Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi and causes potentially life-threatening disease of the heart and gastrointestinal tract. The southern half of the United States contains enzootic cycles of T. cruzi, involving 11 recognized triatomine vector species. The greatest vector diversity and density occur in the western United States, where woodrats are the most common reservoir; other rodents, raccoons, skunks, and coyotes are also infected with T. cruzi. In the eastern United States, the prevalence of T. cruzi is highest in raccoons, opossums, armadillos, and skunks. A total of 7 autochthonous vector-borne human infections have been reported in Texas, California, Tennessee, and Louisiana; many others are thought to go unrecognized. Nevertheless, most T. cruzi-infected individuals in the United States are immigrants from areas of endemicity in Latin America. Seven transfusion-associated and 6 organ donor-derived T. cruzi infections have been documented in the United States and Canada. As improved control of vector- and blood-borne T. cruzi transmission decreases the burden in countries where the disease is historically endemic and imported Chagas' disease is increasingly recognized outside Latin America, the United States can play an important role in addressing the altered epidemiology of Chagas' disease in the 21st century.

Fig. 1.

Photographs of U.S. triatomine species, Triatoma and Paratriatoma. The image size relative to the scale bar represents the average length of each species. Photographs for T. incrassata, T. recurva, and P. hirsuta were unavailable. All photographs are by S. Kjos.

Fig. 2.

Triatomine species diversity in the continental United States and Hawaii by county. States shaded gray have reported at least one species. The states of Kentucky, Maryland, Mississippi, New Jersey, and Pennsylvania have each reported one species but with no locality specified. References are provided in Table 3.

Fig. 3.

Triatomine species geographic distribution by state (gray areas) and county and Trypanosoma cruzi infection status by county in the continental United States and Hawaii. (A) All species; (B) Triatoma gerstaeckeri; (C) T. incrassata; (D) T. indictiva; (E) T. lecticularia; (F) T. neotomae; (G) T. protracta; (H) T. recurva; (I) T. rubida; (J) T. rubrofasciata; (K) T. sanguisuga; (L) Paratriatoma hirsuta. Red, T. cruzi-positive specimens; blue, negative specimens; yellow, no testing reported. References are provided in Table 3.

Fig. 4.

Reports of natural Trypanosoma cruzi infection in U.S. mammals. (A) Raccoons, Virginia opossums, and ringtails; infection of opossums has been reported in Virginia, but no locality was specified. (B) Rodents and mesomammals. An additional report of infected coyotes was published from Virginia, but no locality was specified. (C) Domestic canines. In some states (California, Georgia, Tennessee, and Virginia, shown in dark gray), additional canine clinical cases were reported, but no locality was specified. References are provided in Table 4 for panels A and B and in the text for panel C.