Effects of Non-Susceptible Hosts on the Infection with Trypanosoma cruzi of the Vector Triatoma infestans: an Experimental Model

Vázquez, Diego P.; Canale, Delmi; Gürtler, Ricardo E.

doi:10.1590/s0074-02761999000300024

Cited by 7 publications

(8 citation statements)

References 12 publications

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“…Moreover, the adjusted odds of human infection with T. cruzi increased with the household number of infected dogs or cats and the presence of chickens indoors [29]. An experimental study corroborated that the additional presence of chickens relative to infected guinea pigs reduced bug infection prevalence [30]. A mathematical model of the household transmission of T. cruzi was consistent with this empirical evidence and predicted that the fraction of spring bugs' feeding contacts with humans would decrease with more dogs and chickens in spring because both animal hosts would divert vector feeding contacts [31].…”

Section: Introductionmentioning

confidence: 75%

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

et al. 2014

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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.

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Section: Introductionmentioning

confidence: 75%

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

et al. 2014

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“…Yet the quantitative preference for feeding on dogs only was directly and significantly related to relative dog biomass in the comparison with cats but not with chickens. A laboratory-based comparison of host-feeding choices between chickens and guinea pigs also showed no direct relationship with host biomass [18]. It appears that relative host biomass would play a lesser role in determining feeding choices of T. infestans between two animal host species than in the case of mosquitoes and humans [38], possibly because of differences in behavior between host species.…”

Section: Discussionmentioning

confidence: 94%

“…In laboratory-based host choice experiments of Triatoma sordida (a species typically associated with birds), first-instar nymphs significantly preferred birds to humans [16] whereas fifth-instar nymphs feeding success and bloodmeal size were significantly larger on guinea pigs than on pigeons [17]. Triatoma infestans preferred caged chickens to guinea pigs though not in all replicates [18]. In a simultaneous exposure of four caged vertebrate species to separate groups of fifth-instar nymphs of T. infestans , Triatoma dimidiata and Rhodnius prolixus , none displayed dominant host-feeding preferences among dogs, chickens and opossums but toads were only rarely fed upon [19].…”

Section: Introductionmentioning

confidence: 99%

Strong Host-Feeding Preferences of the Vector Triatoma infestans Modified by Vector Density: Implications for the Epidemiology of Chagas Disease

et al. 2009

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BackgroundUnderstanding the factors that affect the host-feeding preferences of triatomine bugs is crucial for estimating transmission risks and predicting the effects of control tactics targeting domestic animals. We tested whether Triatoma infestans bugs prefer to feed on dogs vs. chickens and on dogs vs. cats and whether vector density modified host choices and other vital rates under natural conditions.MethodologyTwo host choice experiments were conducted in small caged huts with two rooms between which bugs could move freely. Matched pairs of dog–chicken (six) and dog–cat (three) were assigned randomly to two levels of vector abundance and exposed to starved bugs during three nights. Bloodmeals from 1,160 bugs were tested by a direct enzyme-linked immunosorbent assay.Principal FindingsConditional logistic regression showed that dogs were highly preferred over chickens or cats and that vector density modified host-feeding choices. The relative risk of a bug being blood-engorged increased significantly when it fed only on dog rather than chicken or cat. Bugs achieved higher post-exposure weight at higher vector densities and successive occasions, more so if they fed on a dog rather than on a cat.ConclusionsOur findings strongly refute the hypothesis that T. infestans prefers to blood-feed on chickens rather than dogs. An increase in dog or cat availability or accessibility will increase the rate of bug feeding on them and exert strong non-linear effects on R 0. When combined with between-dog heterogeneities in exposure, infection, and infectiousness, the strong bug preference for dogs can be exploited to target dogs in general, and even the specific individuals that account for most of the risk, with topical lotions or insecticide-impregnated collars to turn them into baited lethal traps or use them as transmission or infestation sentinels based on their immune response to Trypanosoma cruzi or bug salivary antigens.

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“…While the empirical literature on Chagas disease ecology points at the importance of non-human hosts in the transmission of T . cruzi to human [31–33], its modelling has often been focused on vector population dynamics with the hope of optimizing vector control interventions targeting the reduction of triatomine abundance and infestation (see [34] for a review). Dynamic compartmental models of T .…”

Section: Introductionmentioning

confidence: 99%

Trypanosoma cruzi transmission dynamics in a synanthropic and domesticated host community

et al. 2019

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Trypanosoma cruzi is the causative agent of Chagas disease, a Neglected Tropical Disease affecting 8 million people in the Americas. Triatomine hematophagous vectors feed on a high diversity of vertebrate species that can be reservoirs or dead-end hosts, such as avian species refractory to T. cruzi. To understand its transmission dynamics in synanthropic and domesticated species living within villages is essential to quantify disease risk and assess the potential of zooprophylaxis. We developed a SI model of T. cruzi transmission in a multi-host community where vector reproduction and parasite transmission depend on a triatomine blood-feeding rate accounting for vector host preferences and interference while feeding. The model was parameterized to describe T. cruzi transmission in villages of the Yucatan peninsula, Mexico, using the information about Triatoma dimidiata vectors and host populations accumulated over the past 15 years. Extensive analyses of the model showed that dogs are key reservoirs and contributors to human infection, as compared to synanthropic rodents and cats, while chickens or other domesticated avian hosts dilute T. cruzi transmission despite increasing vector abundance. In this context, reducing the number of dogs or increasing avian hosts abundance decreases incidence in humans by up to 56% and 39%, respectively, while combining such changes reduces incidence by 71%. Although such effects are only reached over >10-years periods, they represent important considerations to be included in the design of cost-effective Integrated Vector Management. The concomitant reduction in T. cruzi vector prevalence estimated by simulating these zooprophylactic interventions could indeed complement the removal of colonies from the peridomiciles or the use of insect screens that lower vector indoor abundance by ~60% and ~80%. These new findings reinforce the idea that education and community empowerment to reduce basic risk factors is a cornerstone to reach and sustain the key objective of interrupting Chagas disease intra-domiciliary transmission.

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Effects of Non-Susceptible Hosts on the Infection with Trypanosoma cruzi of the Vector Triatoma infestans: an Experimental Model

Abstract: We tested experimentally the effects of the presence of non-susceptible hosts on the infection with

Cited by 7 publications

References 12 publications

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

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

Strong Host-Feeding Preferences of the Vector Triatoma infestans Modified by Vector Density: Implications for the Epidemiology of Chagas Disease

Trypanosoma cruzi transmission dynamics in a synanthropic and domesticated host community

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