Modelling geospatial distributions of the triatomine vectors of Trypanosoma cruzi in Latin America

Abstract

Approximately 150 triatomine species are suspected to be infected with the Chagas parasite, Trypanosoma cruzi, but they differ in the risk they pose to human populations. The largest risk comes from species that have a domestic life cycle and these species have been targeted by indoor residual spraying campaigns, which have been successful in many locations. It is now important to consider residual transmission that may be linked to persistent populations of dominant vectors, or to secondary or minor vectors. The aim of this project was to define the geographical distributions of the community of triatomine species across the Chagas endemic region. Presence-only data with over 12, 000 observations of triatomine vectors were extracted from a public database and target-group background data were generated to account for sampling bias in the presence data. Geostatistical regression was then applied to estimate species distributions and fine-scale distribution maps were generated for thirty triatomine vector species including those found within one or two countries and species that are more widely distributed from northern Argentina to Guatemala, Bolivia to southern Mexico, and Mexico to the southern United States of America. The results for Rhodnius pictipes, Panstrongylus geniculatus, Triatoma dimidiata, Triatoma gerstaeckeri, and Triatoma infestans are presented in detail, including model predictions and uncertainty in these predictions, and the model validation results for each of the 30 species are presented in full. The predictive maps for all species are made publicly available so that they can be used to assess the communities of vectors present within different regions of the endemic zone. The maps are presented alongside key indicators for the capacity of each species to transmit T. cruzi to humans. These indicators include infection prevalence, evidence for human blood meals, and colonisation or invasion of homes. A summary of the published evidence for these indicators shows that the majority of the 30 species mapped by this study have the potential to transmit T. cruzi to humans.

Urban vectors of Chagas disease in the American continent: A systematic review of epidemiological surveys

“…An important point to highlight is that at least 18 species of triatomines belonging to the genera Panstrongylus, Rhodnius and Triatoma occur in urban areas. The results of a study that modeled the geo-spatial distributions (including rural and urban areas) of the thirty most commonly reported triatomine species and putative vectors of T. cruzi partially coincide with our results, showing 14 of our 18 species reported in urban areas [66]. Other species such as R. montenegrensis, R. nasutus, T. barbieri, T. brasiliensis, T. nigromaculata and T. recurva have been found sharing ecotopes with some of the 18 species mentioned above (results not shown).…”

Systematic review on the biology, ecology, genetic diversity and parasite transmission potential of Panstrongylus geniculatus (Latreille 1811) in Latin America

“…(86) Although the presence of P. geniculatus has been recorded in 18 countries, the recent availability of predictive maps can produce a robust summary of its distribution and show its spatial variation so that regions with a high probable risk of vector transmission and transmission through food contamination can be identified. (87) Genetic diversity in P. geniculatus -The Panstrongylus genus is classified as belonging to the Triatomini, a monophyletic tribe. However, the phylogenetic relationships inside this group are far to be cleared because current knowledge is limited and messy.…”

Immature instars of three species of Rhodnius Stål, 1859 (Hemiptera, Reduviidae, Triatominae): morphology, morphometry, and taxonomic implications

“…Arboreal habits are common in the genus, and most are associated with one or more palm species. Among the species studied in this work, R. robustus is found in Bolivia, Colombia, Ecuador, Peru, and Venezuela, as well as northern Brazil [ 2 , 19 ]. In wild environments it is generally found in a variety of palm species, its presence having also been reported in domiciles and peridomiciles [ 20 , 21 ].…”

“…Rhodnius prolixus is considered the most important species in the transmission of Chagas disease in Venezuela, Colombia, and Central America [ 2 , 19 ]. One of the factors that contribute to this is its optimal adaptation to human dwellings.…”