Triatoma brasiliensis Neiva, 1911: food sources and diversity of Trypanosoma cruzi in wild and artificial environments of the semiarid region of Ceará, northeastern Brazil

Abstract

BackgroundKnowledge of triatomine food sources in different ecotopes enables the estimation of T. cruzi transmission risk in diverse environments, as well as its dynamics of dispersion and ecological niche. For Triatoma brasiliensis in the Caatinga, in the northeast of Brazil, seasonal differences influence feeding eclecticism and rates of T. cruzi infection. The objective of the present study was to monitor food sources and to characterize the populations of T. cruzi associated with T. brasiliensis in wild and domestic environments in the Caatinga of northeast Brazil.MethodsA cross-sectional study based on a search for triatomines in wild and domestic environments, was undertaken at five different time periods from 2009 to 2015. Insects from 2015 were used for identification of food sources. Two universal primers, based on the conserved regions of the 12S rRNA locus, were used to amplify fragments of 215 bp. The content of the intestinal tract of triatomines was identified by a comparison between the sequences obtained and those deposited in the GenBank database, using BLAST. In triatomines with parasitological diagnosis of infection by trypanosomatids, xenoculture was performed for the isolation and characterization of strains, using cox2, the amplification of the SL-IL mini-exon intergenic spacer and the polymorphism of the D7 divergent domain of the gene 24αrDNA-LSU.ResultsFood sources were identified in 76.3% (213/279) T. brasiliensis specimens sampled in 2015. The most frequent sources in a total of 20 vertebrate species were: rodents (58%, 123/213), ruminants (30%, 64/213) and cats (6%, 12/213). A total of 49% (44/89) of the samples of T. cruzi isolated in the period from 2009 to 2015 were characterized: TcII (43%, 19/44), TcI (41%, 18/44) and TcIII (16%, 7/44).ConclusionsThe feeding eclecticism of T. brasiliensis shows its importance in maintaining the transmission dynamics of T. cruzi, with evidence of intense circulation between anthropic and wild environments. Attention should be placed on the association among T. brasiliensis, rodents and ruminants, in addition to the presence of TcIII in the study region.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3235-4) contains supplementary material, which is available to authorized users.

Dynamics of food sources, ecotypic distribution and Trypanosoma cruzi infection in Triatoma brasiliensis from the northeast of Brazil

“…Unexpected blood meals were found, such as snakes, raccoons, sylvatic birds and doves, indicating the great variety of T. brasiliensis feeding habits. Of the total blood meals detected, 127 (70%) belong to rodents of Caviidae family-a kind of food source that was already found in other studies [5,15]. As expected, the higher diversity of blood meals in the sylvatic environment was evidenced by Shannon's diversity index.…”

“…The molecular detection of blood meals for T. brasiliensis was already explored, but these studies were limited to small geographic scales [5,15,28]. A detailed study on site-occupancy on T. brasiliensis has already been presented with robust findings, but with subjective inferences on the food sources [14].…”

“…Principal component analysis (PCA) was conducted to rank the three groups of animals according to their importance as the source of food for T. brasiliensis and consequently, their potential as T. cruzi reservoirs. Previous studies showed that rodents of Caviidae family are the main food sources of T. brasiliensis in the sylvatic habitat [5,14,15,18], sometimes found in peridomestic environments [14]. We combined all other mammals because they are also potential T. cruzi reservoirs, but are mainly exotics of Brazilian fauna (as cats, dogs, goats and cows).…”

“…Controversially, the blood meal detection/inferences to test the site-occupancy hypotheses for T. brasiliensis has been applied only locally (i.e. in small geographic scales) [5,14,15,16] and/or are based only on site-observation [14]. Here, the molecular identification of food sources was applied in a wider geographic area, which was implemented with field information on the site-occupancy of T. brasiliensis and molecular T. cruzi detection to infer on the potential reservoirs in ecotopes, in addition to vector (T. brasiliensis) and parasite (T. cruzi) distribution patterns.…”

Spatial distribution of synanthropic triatomines in Piaui State, Northeastern Brazil

“…In this study, the municipalities that registered the presence of T. brasiliensis are located mainly in the semi-arid Caatinga biome. T. brasiliensis is a typical species of this region 35 and naturally inhabits the cracks of rocky outcrops in the semiarid landscape. The present study shows that T. brasiliensis colonizes the interior of houses and documents the presence of nymphs of this species inside households in several municipalities.…”