Triatoma maculata, the Vector of Trypanosoma cruzi, in Venezuela. Phenotypic and Genotypic Variability as Potential Indicator of Vector Displacement into the Domestic Habitat

Abstract

Triatoma maculata is a wild vector of Trypanosoma cruzi, the causative agent of Chagas disease; its incursion in the domestic habitat is scant. In order to establish the possible domestic habitat of T. maculata, we evaluated wing variability and polymorphism of genotypic markers in subpopulations of T. maculata that live in different habitats in Venezuela. As markers, we used the mtCyt b gene, previously apply to evaluate population genetic structure in triatomine species, and the β-tubulin gene region, a marker employed to study genetic variability in Leishmania subgenera. Adults of T. maculata were captured in the period 2012–2013 at domestic, peridomestic (PD), and wild areas of towns in the Venezuelan states of Anzoátegui, Bolívar, Portuguesa, Monagas, Nueva Esparta, and Sucre. The phenotypic analysis was conducted through the determination of the isometric size and conformation of the left wing of each insect (492 individuals), using the MorphoJ program. Results reveal that insects of the domestic habitat showed significant reductions in wing size and variations in anatomical characteristics associated with flying, in relation to the PD and wild habitats. The largest variability was found in Anzoátegui and Monagas. The genotypic variability was assessed by in silico sequence comparison of the molecular markers and PCR-RFLP assays, demonstrating a marked polymorphism for the markers in insects of the domestic habitat in comparison with the other habitats. The highest polymorphism was found for the β-tubulin marker with enzymes BamHI and KpnI. Additionally, the infection rate by T. cruzi was higher in Monagas and Sucre (26.8 and 37.0%, respectively), while in domestic habitats the infestation rate was highest in Anzoátegui (22.3%). Results suggest domestic habitat colonization by T. maculata that in epidemiological terms, coupled with the presence in this habitat of nymphs of the vector, represents a high risk of transmission of Chagas disease.

Untangling the transmission dynamics of primary and secondary vectors of Trypanosoma cruzi in Colombia: parasite infection, feeding sources and discrete typing units

“…By contrast, herein the frequency of T. cruzi infection was 67.6% and the percentage of feeding with human blood was 75.0% with the presence of TcIDom in some specimens collected in peridomiciliary habitats. Recent studies in Colombia and Venezuela have revealed infection frequencies between 38.0 and 75.0% and the presence of “TcIb” genotype that is associated with the peridomestic cycle [26, 27, 33, 34, 39, 40]. Regarding the DTUs herein detected, most of the specimens were infected with TcI and TcIII (sylvatic DTUs) and domestic specimens harbored TcIII suggesting how T. maculata can connect domestic and sylvatic transmision cycles (Fig.…”

Triatoma maculata colonises urban domicilies in Boa Vista, Roraima, Brazil

“…In Venezuela T. maculata is regarded as the second most important vector species in the transmission of Chagas disease, after Rhodnius prolixus . R. prolixus is related to domiciliated transmission, invasion and reinfestation of houses after control measures in Venezuela (Feliciangeli & Torrealba 1977, González-Brítez et al 2010, Reyes-Lugo et al 2011) where oral outbreaks have been reported, mainly related to the presence of sylvatic and peridomicile triatomine species (Rojas et al 2008, García-Alzate et al 2014, Alarcón de Noya et al 2015).…”

“…These processes stimulate adult dispersion, which might find a receptive environment in artificial ecotopes (Forattini et al 1979, Aragão 1983, González-Brítez et al 2010). In Venezuela this process has been described for T. maculata using geometric morphometry to analyse wings and by the variability in the b -tubuline marker, coupled with the presence of nymphs inside the houses (García-Alzate et al 2014). In the present observation in Roraima, we found eggs, nymphs in all development stages and one adult, which is the first encounter of T. maculata colonising domiciles in Brazil.…”

Trypanosoma cruzi, the Causal Agent of Chagas Disease: Boundaries between Wild and Domestic Cycles in Venezuela

“…T. maculata is found in palms, dry trees, wooden fences, and bird nests near human dwellings. Its domiciliation, in function to phenotypic and genotypic discrimination according to its ecotopes, guarantee the previous consideration about its presence a risk factor for parasite transmission in Brazil, Colombia, and Venezuela ( 11 – 13 ).…”