Patterns of house infestation dynamics by non-domiciliatedTriatoma dimidiatareveal a spatial gradient of infestation in rural villages and potential insect manipulation byTrypanosoma cruzi

Abstract

Summaryobjective Chagas disease is a major vector-borne parasitic disease in Latin America, primarily transmitted to humans by triatomine vectors. Non-domiciliated triatomine species such as Triatoma dimidiata in the Yucatan peninsula, Mexico, can transiently invade houses and are emerging as a major challenge to control Trypanosoma cruzi transmission to humans. We analyzed the spatio-temporal spreading of house infestation by T. dimidiata in four rural villages.methods Triatomines were collected in four rural villages over a 2 years period, and the spatio-temporal patterns of infestation were analyzed.results Triatomines were consistently more abundant at the periphery of villages than in centers, indicating a much higher risk of T. cruzi transmission at the periphery. Male T. dimidiata were found further in the center of the village, while females remained closer to the periphery, suggesting differential dispersal capabilities between sexes, although the timing of dispersal appeared identical. Surprisingly, infected females were consistently collected in houses much further from the surrounding bushes than non-infected females, while the distribution of males was unaffected by their T. cruzi infection status, suggesting an increased dispersal capability in infected females.conclusion The spatial structure of infestation should be taken into account for the prioritization of vector control activities within villages, and spatially targeted interventions may be explored. A potential vector manipulation by T. cruzi, observed for the first time in triatomines, may favor parasite transmission to new hosts.

High Frequency of Human Blood in Triatoma dimidiata Captured Inside Dwellings in a Rural Community in the Yucatan Peninsula, Mexico, but Low Antibody Seroprevalence and Electrocardiographic Findings Compatible with Chagas Disease in Humans

“…Natural infection rate is one important factor; several studies have reported a wide range of natural infection in T. dimidiata that varies from very low, such as 4%, to high natural infection, such as up to 34%. 3,4,16 For example, low natural infection of 4% has been found in sylvan populations of T. dimidiata in the Yucatan state, Mexico, whereas in the Peten, Guatemala, it can reach up to 25% in sylvan populations. 4,17 In this work, we found natural infection of 38%; these data are similar to those results in the work by Ramirez-Sierra and others, 3 which reported 34% natural infection in a rural community in the Yucatan state, Mexico.…”

“…1,2 In the Yucatan Peninsula of Mexico, cryptic species were found; specimens from Yucatan should be considered as separate species rather than T. dimidiata. 2 Several studies have shown that the vector population in the domestic and peridomestic cycles in the Yucatan Peninsula comes from sylvan stocks and presents clear seasonality [3][4][5][6][7] . In this cycle of transmission, several reservoirs are involved: infected Didelphys virginiana and Peromyscus leucopus have been found in the sylvan cycle, and in the peridomestic and domestic cycles, Canis familiaris, Rattus rattus, Mus musculus, and humans have been found at different rates.…”

Comparative Field Trial of Alternative Vector Control Strategies for Non-Domiciliated Triatoma dimidiata

“…Vector control interventions, including conventional indoor residual insecticide spraying, peridomicile management, and the installation of insect screens and insecticide-impregnated curtains, were then applied to subsets of houses, and triatomine abundance in the houses was monitored for up to two consecutive infestation seasons. First, because of each house's location in the village, and particularly each house's distance from the surrounding forest/bushes, is a key factor for house infestation by non-domiciliated triatomines, 31 we ensured that houses receiving control interventions were located at a comparable distance from the periphery as houses without vector control interventions (permutation test P = 0.13, P = 0.39, and P = 0.10 in the villages of Sudzal, Teya, and Bokoba, respectively) and thus were exposed to a comparable risk for infestation.…”

Spatial patterns and eco-epidemiological systems – part I: multi-scale spatial modelling of the occurrence of Chagas disease insect vectors

“…Where insects are transiently present and/or in very low density in the domestic habitat, community participation has been found highly reliable for entomologic surveys and also shown to be more sensitive than manual collection (Barbu et al, 2010;Ramirez-Sierra et al, 2010). Although we initially chose manual collection, it was performed by the same person to avoid operator bias.…”

“…However, studies that explicitly take into account the spatial dimension remain rare. For example, Ramirez-Sierra et al (2010) studied domiciliary infestation of four villages on the Yucatan peninsula, Mexico with regard to insect sex, infection status and distance between houses and the village boundary, the latter variable being suggested by observations and the outcome of a model proposed by Slimi et al (2009). In a comparable way, Roux et al (2009) used several attributes to explicitly characterise the spatial structure of a Brazilian village in the semi-arid region of Bahia: (i) distance to the village centre; (ii) distance to the specific house where the majority of the insects was found; and (iii) relative situations of the domiciliary unit (central or peripheral and connected or isolated).…”