Ecological, Social and Biological Risk Factors for Continued Trypanosoma cruzi Transmission by Triatoma dimidiata in Guatemala

Abstract

BackgroundChagas disease transmission by Triatoma dimidiata persists in Guatemala and elsewhere in Central America under undefined ecological, biological and social (eco-bio-social) conditions.MethodologyEco-bio-social risk factors associated with persistent domiciliary infestation were identified by a cross-sectional survey and qualitative participatory methods. Quantitative and qualitative data were generated regarding Trypanosoma cruzi reservoirs and triatomine hosts. Blood meal analysis and infection of insects, dogs and rodents were determined. Based on these data, multimodel inference was used to identify risk factors for domestic infestation with the greatest relative importance (>0.75).Principal FindingsBlood meal analysis showed that 64% of 36 bugs fed on chickens, 50% on humans, 17% on dogs; 24% of 34 bugs fed on Rattus rattus and 21% on Mus musculus. Seroprevalence among 80 dogs was 37%. Eight (17%) of 46 M. musculus and three (43%) of seven R. rattus from households with infected triatomines were infected with T. cruzi Distinct Typing Unit I. Results from interviews and participatory meetings indicated that vector control personnel and some householders perceived chickens roosting and laying eggs in the house as bug infestation risk factors. House construction practices were seen as a risk factor for bug and rodent infestation, with rodents being perceived as a pest by study participants. Multimodel inference showed that house infestation risk factors of high relative importance are dog density, mouse presence, interior wall plaster condition, dirt floor, tile roofing and coffee tree presence.Conclusions/SignificancePersistent house infestation is closely related to eco-bio-social factors that maintain productive T. dimidiata habitats associated with dogs, chickens and rodents. Triatomine, dog and rodent infections indicate active T. cruzi transmission. Integrated vector control methods should include actions that consider the role of peridomestic animals in transmission and community memberś level of knowledge, attitudes and practices associated with the disease and transmission process.

Information to Act: Household Characteristics are Predictors of Domestic Infestation with the Chagas Vector Triatoma dimidiata in Central America

“…This modeling technique is now the preferred method in ecological modeling for triatominae infestation. 11,12,45 We conclude that in this region, the rural housing factors included in our hypothesis can help predict houses with live infestation and some variables will have more important contributions to the predictions. Including spatial variability and signs of infestation improved the predictions.…”

“…13 Other studies in Jutiapa found that walls made of adobe with deteriorated or no plastering were associated with Triatoma dimidiata presence. 11,15 It can be noted that these variation in significance of association of factors from one place to the other could be a consequence of the lack of a balanced design. For instance, Jutiapa and Baja Verapaz might not have similar frequency of adobe and bajarequepalopique homes and this could affect the associations found.…”

“…[7][8][9][10] The risk factors associated with the odds of Triatoma dimidiata infestation have been studied across the distribution of this species. [11][12][13][14][15][16][17][18][19] In Yucatan, factors from outside of the houses, such as proximity to streetlights, proximity to vegetation, and the presence of animals or rock piles in the peridomicile, are risk factors that attract non-domiciliated Triatoma dimidiata into houses. 12,16 In central America, where Triatoma dimidiata is considered domiciliated, the type of house construction materials and their quality are very important risk factors for infestation.…”

“…14 Studies conducted at the household level in the Guatemalan departments of Jutiapa 11,15 and Chiquimula 13 found that poor sanitary conditions or a disorganized house, dirt floors, walls made of rustic materials (adobe, bajareque), and low-quality or nonexistent wall plastering, tile roofing, dog density, mice presence, and coffee trees around the house are factors associated with increased odds of Triatoma dimidiata presence. The presence of triatomine-like feces in the house increased the odds of live infestation in the Chiquimula study.…”

Poor Housing Construction Associated with Increased Malaria Incidence in a Cohort of Young Ugandan Children

“…Nondirt floors and cinder block walls have been associated with lower prevalence of vector-borne Chagas disease. 27 People living in rural households with dirt floors are at higher risk of acquiring soil-transmitted helminths Ascaris lumbricoides and Trichuris trichiura infections. 28 Improved natural ventilation HOUSE CONSTRUCTION AND MALARIA RISK in a household because of an increase in windows and entryways is associated with lower transmission of air-borne pathogens such as tuberculosis.…”