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Identification of bloodmeal sources of triatomines captured in the Paraguayan Chaco region of South America by means of molecular biology analysis.

ABSTRACT: The Paraguayan Chaco is an isolated environment with its own unique ecosystem. In this region, Chagas disease remains a health problem. Chagas disease is caused by the parasite Trypanosoma cruzi, and it is primarily transmitted by triatomines. In order to identify the blood meal sources of triatomines, specimens of the vector were collected in domestic and peridomestic areas and the PCR-RFLP method was implemented. Cytochrome b was amplified from the samples and later subjected to digestion with two restriction enzymes: Hae III and Xho I.It was possible to generate distinct restriction patterns on the amplified material to identify several blood meal sources for the vectors. We employed the blood from several species as positive controls: human, chicken, canine, feline, and armadillo blood. However, we identified only 3 sources for the blood meals of the insect vectors: human, chicken and canine blood. In total, 76 triatomines were captured. T. cruzi was not found in any of them. In 61% of the captured specimens, the blood meal sources for the vectors could be identified. In 30% of these cases, the presence of DNA from more than one vertebrate was detected in the same triatomine. The most common blood meal source found was chicken blood. The presence of human and chicken blood in triatomines captured in domestic and peridomestic areas strongly suggests that the parasite can freely move amongst both areas regardless of food availability. Free vector movement in these areas constitutes an epidemiological threat for the inhabitants of the community under study.

SUBMITTER: Fraenkel S

PROVIDER: S-EPMC7144232 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundAlthough domestic infestations by Triatoma infestans have been successfully controlled across Latin America, in areas of the Gran Chaco region, recurrent post-spraying house colonization continues to be a significant challenge, jeopardizing Chagas disease vector control and maintaining active Trypanosoma cruzi transmission.Methodology/principal findingsTo investigate the dynamics of triatomine reinfestation in a rural area of the Paraguayan Chaco, genetic characterization (based on 10 microsatellite loci and cytochrome B sequence polymorphisms) was performed on baseline and reinfestant T. infestans (n = 138) from four indigenous communities and adjacent sylvatic sites. House quality and basic economic activities were assessed across the four communities. Significant genetic differentiation was detected among all baseline triatomine populations. Faster reinfestation was observed in the communities with higher infestation rates pre-spraying. Baseline and reinfestant populations from the same communities were not genetically different, but two potentially distinct processes of reinfestation were evident. In Campo Largo, the reinfestant population was likely founded by domestic survivor foci, with reduced genetic diversity relative to the baseline population. However, in 12 de Junio, reinfestant bugs were likely derived from different sources, including survivors from the pre-spraying population and sympatric sylvatic bugs, indicative of gene-flow between these habitats, likely driven by high human mobility and economic activities in adjacent sylvatic areas.Conclusions/significanceOur results demonstrate that sylvatic T. infestans threatens vector control strategies, either as a reinfestation source or by providing a temporary refuge during insecticide spraying. Passive anthropogenic importation of T. infestans and active human interactions with neighboring forested areas also played a role in recolonization. Optimization of spraying, integrated community development and close monitoring of sylvatic areas should be considered when implementing vector control activities in the Gran Chaco.

Project description:The South American continent presents a great diversity of biomes, whose ecosystems are constantly threatened by the expansion of human activity. The emergence and re-emergence of viral populations with impact on the human population and ecosystem have shown increases in the last decades. In deference to the growing accumulation of genomic data, we explore the potential of South American-related public databases to detect signals that contribute to virosphere research. Therefore, our study aims to investigate public databases with emphasis on the surveillance of viruses with medical and ecological relevance. Herein, we profiled 120 "sequence read archives" metagenomes from 19 independent projects from the last decade. In a coarse view, our analyses identified only 0.38% of the total number of sequences from viruses, showing a higher proportion of RNA viruses. The metagenomes with the most important viral sequences in the analyzed environmental models were 1) aquatic samples from the Amazon River, 2) sewage from Brasilia, and 3) soil from the state of São Paulo, while the models of animal transmission were detected in mosquitoes from Rio Janeiro and Bats from Amazonia. Also, the classification of viral signals into operational taxonomic units (OTUs) (family) allowed us to infer from metadata a probable host range in the virome detected in each sample analyzed. Further, several motifs and viral sequences are related to specific viruses with emergence potential from Togaviridae, Arenaviridae, and Flaviviridae families. In this context, the exploration of public databases allowed us to evaluate the scope and informative capacity of sequences from third-party public databases and to detect signals related to viruses of clinical or environmental importance, which allowed us to infer traits associated with probable transmission routes or signals of ecological disequilibrium. The evaluation of our results showed that in most cases the size and type of the reference database, the percentage of guanine-cytosine (GC), and the length of the query sequences greatly influence the taxonomic classification of the sequences. In sum, our findings describe how the exploration of public genomic data can be exploited as an approach for epidemiological surveillance and the understanding of the virosphere.

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Identification of bloodmeal sources of triatomines captured in the Paraguayan Chaco region of South America by means of molecular biology analysis.

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