Domestic Animal Hosts Strongly Influence Human-Feeding Rates of the Chagas Disease Vector Triatoma infestans in Argentina

Abstract

BackgroundThe host species composition in a household and their relative availability affect the host-feeding choices of blood-sucking insects and parasite transmission risks. We investigated four hypotheses regarding factors that affect blood-feeding rates, proportion of human-fed bugs (human blood index), and daily human-feeding rates of Triatoma infestans, the main vector of Chagas disease.MethodsA cross-sectional survey collected triatomines in human sleeping quarters (domiciles) of 49 of 270 rural houses in northwestern Argentina. We developed an improved way of estimating the human-feeding rate of domestic T. infestans populations. We fitted generalized linear mixed-effects models to a global model with six explanatory variables (chicken blood index, dog blood index, bug stage, numbers of human residents, bug abundance, and maximum temperature during the night preceding bug catch) and three response variables (daily blood-feeding rate, human blood index, and daily human-feeding rate). Coefficients were estimated via multimodel inference with model averaging.FindingsMedian blood-feeding intervals per late-stage bug were 4.1 days, with large variations among households. The main bloodmeal sources were humans (68%), chickens (22%), and dogs (9%). Blood-feeding rates decreased with increases in the chicken blood index. Both the human blood index and daily human-feeding rate decreased substantially with increasing proportions of chicken- or dog-fed bugs, or the presence of chickens indoors. Improved calculations estimated the mean daily human-feeding rate per late-stage bug at 0.231 (95% confidence interval, 0.157–0.305).Conclusions and SignificanceBased on the changing availability of chickens in domiciles during spring-summer and the much larger infectivity of dogs compared with humans, we infer that the net effects of chickens in the presence of transmission-competent hosts may be more adequately described by zoopotentiation than by zooprophylaxis. Domestic animals in domiciles profoundly affect the host-feeding choices, human-vector contact rates and parasite transmission predicted by a model based on these estimates.

Reservoir host competence and the role of domestic and commensal hosts in the transmission of Trypanosoma cruzi

“…Increasing the number of chickens in human sleeping quarters (for hypothetical zooprophylactic effects) very slightly decreased the human prevalence rate but increased the size of the infected summer bug population. The available empirical data are consistent with model predictions (Cohen and Gürtler, 2001;Gürtler et al, 2014bGürtler et al, , 2005Gürtler et al, , 1997. Both the transmission model and data illustrate a paradox: increasing the access to (or introducing) a suitable, non-susceptible host on which bugs blood-feed frequently, such as chickens, increases the infected-bug population in the presence of other domestic reservoir hosts.…”

“…For T. infestans collected from all (peri)domestic bug habitats in mid-spring, the median feeding interval was 4.1 days in human sleeping quarters and varied widely from 2.8 days in chicken coops to 10.2 days in kitchens (Gürtler et al, 2014b).…”

Landscape ecology of Trypanosoma cruzi in the southern Yucatan Peninsula

“…Recent studies on the ecological connectivity of vector and parasite host communities within anthropogenic landscapes are providing novel insights into the spatial epidemiology linked to T. cruzi transmission, vector population dynamics, and mammal host metacommunities (Ramsey et al, 2012;Gottdenker et al, 2014;Fernandez et al, 2014). Metacommunities resulting from habitat filtering in anthropogenic landscapes influence bloodmeal use by triatomines, and generally increase T. cruzi prevalence (Gottdenker et al, 2012;Ramsey et al, 2012;Gurtler et al, 2014). Furthermore, regional-scale phylogeographic studies of T. cruzi highlight the influence of sylvatic habitats surrounding human-transformed land as sources of parasite diversity (Ocana-Mayorga et al, 2010;Lima et al, 2014a).…”

Filling dynamics of the Brindley’s glands in the blood-sucking bug Triatoma infestans (Hemiptera: Reduviidae)

“…In peridomestic populations, for instance, adults fed every 2.9, 4.3, 7 and 5.6 days in spring, summer, fall and winter, respectively (Ceballos et al, 2005). Domestic populations, however, predictably show more stable feeding rates of 4 days between meals (Gürtler et al, 2014). As a whole, feeding rates in T. infestans are high, and according to our results, this would imply that the Brindley's glands are probably full most of the time.…”