Abstract
We used an individual-based molecular multisource approach to assess the epidemiological importance of Triatoma brasiliensis collected in distinct sites and ecotopes in Rio Grande do Norte State, Brazil. In the semi-arid zones of Brazil, this blood sucking bug is the most important vector of Trypanosoma cruzi—the parasite that causes Chagas disease. First, cytochrome b (cytb) and microsatellite markers were used for inferences on the genetic structure of five populations (108 bugs). Second, we determined the natural T. cruzi infection prevalence and parasite diversity in 126 bugs by amplifying a mini-exon gene from triatomine gut contents. Third, we identified the natural feeding sources of 60 T. brasiliensis by using the blood meal content via vertebrate cytb analysis. Demographic inferences based on cytb variation indicated expansion events in some sylvatic and domiciliary populations. Microsatellite results indicated gene flow between sylvatic and anthropic (domiciliary and peridomiciliary) populations, which threatens vector control efforts because sylvatic population are uncontrollable. A high natural T. cruzi infection prevalence (52–71%) and two parasite lineages were found for the sylvatic foci, in which 68% of bugs had fed on Kerodon rupestris (Rodentia: Caviidae), highlighting it as a potential reservoir. For peridomiciliary bugs, Galea spixii (Rodentia: Caviidae) was the main mammal feeding source, which may reinforce previous concerns about the potential of this animal to link the sylvatic and domiciliary T. cruzi cycles.
Highlights
Blood-sucking bugs (Triatominae, Reduviidae, Hemiptera) are vectors of the parasite Trypanosoma cruzi (Kinetoplastida, Trypanosomatidae), which causes Chagas disease
We suggested that Kerodon rupestris (Rodentia: Caviidae) may be a potential parasite reservoir, because most sylvatic bugs had fed on this rodent and were infected with T. cruzi, population genetics results indicated that vector control efforts in domiciles are threatened by gene flow from the perennial sylvatic foci with high T. cruzi prevalence
We identified 81 adult insects as T. brasiliensis by morphology, and the remaining 216 immature insects were identified as T. brasiliensis based on our molecular analysis
Summary
Blood-sucking bugs (Triatominae, Reduviidae, Hemiptera) are vectors of the parasite Trypanosoma cruzi (Kinetoplastida, Trypanosomatidae), which causes Chagas disease. More than five million people are infected, and approximately 70 million live at risk [1]. An intensive and expensive Chagas Disease Control Program (PCDCh)—launched by the Ministry of Health of Brazil—was established in this country in 1975 directed primarily at Triatoma infestans—the vector responsible for most of cases of Chagas disease transmission in Brazil. In 2006, T. cruzi transmission by T. infestans, had been officially interrupted [2]. Once it became clear that T. cruzi was no longer actively transmitted by T. infestans, investment in entomological surveillance and control programs decreased. Concerns are high regarding the potential of native triatomines, such as Triatoma brasiliensis, for re-emerging hyperendemic Chagas disease foci in Brazil [3]
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