Trypanosomatids in Small Mammals of an Agroecosystem in Central Brazil: Another Piece in the Puzzle of Parasite Transmission in an Anthropogenic Landscape

Abstract

We surveyed infection by Trypanosoma spp. and Leishmania spp. in small wild mammals from Cumari, Goiás State aiming to investigate the diversity of trypanosomatid in a modified landscape of the Brazilian Cerrado (and possible infection overlapping with canids from the same area). Blood, skin, spleen, and liver samples were collected for parasitological, serological, and molecular assays. Gracilinanus agilis was the most abundant species (N = 70; 48.6%) and it was the only one with patent parasitemia. Characterization by mini-exon and 18SrDNA targets were achieved in 7/10 hemocultures with positive fresh blood examination, which confirmed the T. cruzi infection by Discrete Typing Units (DTU) TcI in single (N = 2) and mixed infections with other DTUs (N = 5). T. rangeli and T. dionisii were detected in skin fragments from Didelphis albiventris and Oecomys cleberi, respectively. G. agilis were found to be infected by L. braziliensis and L. guyanensis, while Leishmania sp. DNA was detected in the liver of Oligoryzomys nigripes and Calomys expulsus. Subpatent infection by T. cruzi and Leishmania sp. was serologically detected in 15% and 9% of the small mammal fauna, respectively. Small mammals from Cumari are included in T. cruzi and Leshmania spp. transmission cycles, showing a higher diversity of trypanosomatid species and/or genotypes than that observed in canids of the same agroecosystem.

Wild and Domestic Canids and Their Interactions in the Transmission Cycles of Trypanosoma Cruzi and Leishmania spp. in an Area of the Brazilian Cerrado

“…Positive hemocultures were detected in dogs, L. vetulus and C. thous, and it has been shown that these animals share at least one DTU of T. cruzi (TcIII) [ 10 ]. Although we were not able to distinguish the genotype/s involved (TcIII/TcV), previous studies using RFLP-PCR in samples from this two hoary foxes confirmed the infection by DTU TcIII [ 11 ], a genotype also found in marsupials ( Gracilinanus agilis ) from the same area [ 31 ]. Considering the pattern observed for experimentally infected domestic dogs, someone can expect that both wild and domestic canids from the area present a short period of patent parasitemia during the initial phase of infection (rarely demonstrated by positive hemocultures in this study), followed by a later phase with undetectable parasitemia, even in reinfections [ 39 ].…”

“…Both T. cruzi and Leishmania spp. infect wild and domestic canids at Limoeiro region, besides small mammals [ 31 ], and maintenance of these parasites by canids occurs despite the low rate of positive parasitological assays. Canids probably become infected through their exposure and consumption of infected vectors and prey.…”

“…Both T cruzi and Leishmania spp. infect wildlife and domestic canids from Limoeiro region, and infection rates were higher in wild canids and small mammals than in dogs [ 31 ]. The wider spatial distribution of T. cruzi is probably a consequence of the higher infection rate by this parasite in all studied mammals.…”

“…In addition, for the first time we detected T. cruzi infection in maned wolves in this area. Infection rates were higher in wild canids, followed by wild small mammals and domestic dogs [ 31 ]. The rate of infection by T. cruzi in a specific host is driven by contact processes vector–parasite–environment–host; thus, we might expect that these ecological dissimilarities lead to different infection ratios [ 10 ].…”

“…Canids appear to behave as selective filters of parasite species/genotypes (controlling and maintaining infection at low parasitism levels) when compared to small mammals, where greater richness of trypanosomatids was detected [ 31 ]. Interactions and competitive exclusion between tripanosomatid species and/or T. cruzi subpopulations certainly take a role in modulating infection ratios [ 10 ].…”