Molecular Epidemiology of Chagas Disease in the Wild Transmission Cycle: The Evaluation in the Sylvatic Vector Mepraia spinolai from an Endemic Area of Chile

Abstract

Abstract. The sylvatic transmission cycle of Chagas disease in Chile is composed of wild mammals and insects of the genus Mepraia . We determined infection rates and Trypanosoma cruzi genotypes in Mepraia spinolai . We collected 227 insects from two ecologically contrasting areas to assess T. cruzi infection. Polymerase chain reaction (PCR)-amplified minicircle DNAs were characterized by Southern blot and hybridization tests with genotype-specific probes. Infection in insects from the more fertile area was almost 2-fold higher than in the poorer area. The genotype TCI was the most prevalent and other genotypes such as TCIIb, TCIId, and TCIIe were found at lower rates. The areas differed in their genotype distribution but not in their genotype diversity. We suggest that the difference in abundance and richness of mammals between the areas may be producing the detected infection levels in vectors. Our results are compared with those reported for mammals from the same area.

Trypanosoma cruzi Genotypes in Mepraia gajardoi from Wild Ecotopes in Northern Chile

“…There were few cases of mixed infections compared with those in M. spinolai, in which T. cruzi infection can reach up to 46.2% in some areas of central Chile, with up to half of the insects containing mixed infections. 17 Our results indicate that infection would not be widely spread in the ecotopes studied. One explanation could be that blood donor vertebrates inhabiting coastal areas may be refractory or dead-end hosts for maintaining and propagating T. cruzi.…”

“…25 The finding of Tc VI in ecotope 2 is similar to findings in northern Argentina, where this lineage is frequently found in humans, T. infestans, and dogs. 20,26 In contrast, Tc I is the most prevalent lineage found in M. spinolai at 31 S. 17 A high prevalence of Tc II was found in ecotope 1, which is the same lineage detected in Mepraia sp., in a coastal locality at 24 S. Different vertebrate hosts maintaining vector populations could explain the dissimilar geographic distribution of T. cruzi lineages in the two study ecotopes. These different host species in two types of ecotopes studied could transmit different T. cruzi lineages.…”

Temporal Fluctuation of Infection with Different Trypanosoma cruzi Genotypes in the Wild Rodent Octodon degus

“…This finding is common for T. cruzi because several mammals and vectors are infected with more than one T. cruzi genotype, 4,5 which results in recombination and hybrid genotypes. 8 We report that infection of rodents can show temporal fluctuations with different T. cruzi genotypes, which is probably the result of fluctuation of relative proportions of parasite loads of different genotypes in peripheral blood.…”

“…4 Recent studies of T. cruzi genotypes circulating in the wild vector in this disease-endemic area showed that TCI and TCII are the most prevalent genotypes. 5 We suggest that both rodent species showed moderate or high levels of parasitemia. We used xenodiagnosis with two triatomine species because insect vectors amplify T. cruzi in the midgut, which enables easy detection.…”

“…[3][4][5] After a short acute or primary infection, the mammal host sustains subclinical infections, which are microscopically undetectable in peripheral blood during the undetermined and chronic phases. Conversely, parasitemia in those phases is detected only by polymerase chain reaction (PCR).…”