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

Background:the 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.methods:a 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.findings:median 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 significance:based 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. © 2014 gürtler et al.