The sylvatic transmission cycle of Trypanosoma cruzi in the Humid Chaco of Argentina.

OROZCO MM; ENRIQUEZ GF,; ALVARADO-OTEGUI JA,,; CARDINAL MV; SCHIJMAN AG; KITRON, U; GURTLER RE

Congreso; 61st Annual Meeting of the American Society of Tropical Medicine and Hygiene,; 2012

A wide variety of wild mammals (e.g., marsupials, edentates, rodents and primates) are reservoir hosts of Trypanosoma cruzi. Understanding the complex epidemiology of T. cruzi and the variety of transmission cycles requires a representative picture of parasite genetic diversity −currently classified into six Discrete Typing Units (DTUs). We estimated the prevalence and diversity of T. cruzi infection in wild mammals of a well-defined rural area (Pampa del Indio) in Chaco, northern Argentina. A total of 195 mammals from 13 identified species were captured in four surveys conducted between 2008 and 2011 and examined for infection by xenodiagnosis and kDNA-PCR. A total of the 27 (14%) were xenodiagnosis-positive: 12 of 31 (29%) Didelphis albiventris opossums and among armadillos, 12 of 29 (46%) Dasypus novemcinctus, 2 of 15 (13%) Tolypeutes matacus, and one of 16 (6%) Chaetophractus vellerosus. A total of 15 xenodiagnosis-negative animals were kDNA-PCR-positive, including 4 D. albiventris opossums, 1 Euphractus sexcinctus and 3 D. novemcinctus armadillos, 5 Thylamys pusilla (Chaco fat-tailed opossum), and 2 small rodents (unidentified species). Using SAT-DNA-PCR we confirmed T. cruzi infection in one D. novemcinctus and two T. pusilla positive by kDNA-PCR only. These are the first findings of T. cruzi in T. pusilla and TcIII in C. vellerosus and T. matacus from Argentina. A PCR-based strategy showed that all opossums were infected with DTU TcI and all armadillos with TcIII, implying separate parasite transmission cycles. Wild mammals had no evidence of parasite DTUs infecting local domestic dogs, cats or Triatoma infestans bugs (TcV and TcVI). Sylvatic transmission cycles of T. cruzi in the dry and humid Chaco differ in the composition of the main reservoir hosts.