Host Life History Strategy, Species Diversity, and Habitat Influence Trypanosoma cruzi Vector Infection in Changing Landscapes

Abstract

BackgroundAnthropogenic land use may influence transmission of multi-host vector-borne pathogens by changing diversity, relative abundance, and community composition of reservoir hosts. These reservoir hosts may have varying competence for vector-borne pathogens depending on species-specific characteristics, such as life history strategy. The objective of this study is to evaluate how anthropogenic land use change influences blood meal species composition and the effects of changing blood meal species composition on the parasite infection rate of the Chagas disease vector Rhodnius pallescens in Panama.Methodology/Principal Findings R. pallescens vectors (N = 643) were collected in different habitat types across a gradient of anthropogenic disturbance. Blood meal species in DNA extracted from these vectors was identified in 243 (40.3%) vectors by amplification and sequencing of a vertebrate-specific fragment of the 12SrRNA gene, and T. cruzi vector infection was determined by pcr. Vector infection rate was significantly greater in deforested habitats as compared to contiguous forests. Forty-two different species of blood meal were identified in R. pallescens, and species composition of blood meals varied across habitat types. Mammals (88.3%) dominated R. pallescens blood meals. Xenarthrans (sloths and tamanduas) were the most frequently identified species in blood meals across all habitat types. A regression tree analysis indicated that blood meal species diversity, host life history strategy (measured as rmax, the maximum intrinsic rate of population increase), and habitat type (forest fragments and peridomiciliary sites) were important determinants of vector infection with T. cruzi. The mean intrinsic rate of increase and the skewness and variability of rmax were positively associated with higher vector infection rate at a site.Conclusions/SignificanceIn this study, anthropogenic landscape disturbance increased vector infection with T. cruzi, potentially by changing host community structure to favor hosts that are short-lived with high reproductive rates. Study results apply to potential environmental management strategies for Chagas disease.

Sylvatic host associations of Triatominae and implications for Chagas disease reservoirs: a comprehensive review and new host records based on archival specimens

“…In contrast, females may be stationary after (Table 2), all of which were previously known to be capable of hosting the parasite [7]. 261 We did not see evidence of double peaks in our chromatographs and direct sequencing 266 always resulted in a single, uncontroversial host sequence, similar to results from other studies 267 conducted using similar primers [49], but in contrast to other studies where cloning of the PCR 268 product was performed and as many as four hosts were detected from a single specimen [50]. may reflect the sylvatic nature of most of our collecting sites and, potentially, the rigorous 278 sterilization protocol we utilized.…”

Rodent reservoirs of future zoonotic diseases

“…From previous studies in wildlife, it is clear that infection patterns can be the result of complex relationships between hosts and parasites that depend on the lifecycle and transmission mode of the parasite as well as the life history strategies, tradeoffs, and ecological context of host species (15)(16)(17). By simultaneously considering all rodent species and the zoonotic infectious agents that they are known to carry, our models identified trait profiles suggesting that rodent reservoirs are distinguished from other rodent species by a fast-paced life history strategy (Fig.…”

Human health impacts of ecosystem alteration

“…In field experiments, exposure to hantavirus increases when mammalian diversity falls (56). For Chagas disease in Panama and the Brazilian Amazon, risk of human exposure is positively correlated with reduced mammalian species diversity (57,58). This suite of findings has led to the proposal of a general principle of disease ecology-the "dilution effect"-whereby a greater diversity of intermediate hosts can dilute the pool of hosts that amplify transmission (competent hosts), resulting in decreased exposure to vector-borne disease (59,60).…”

“…Some recent research suggests that immunological tolerance, and hence high host competence, tends to characterize the species that are intrinsically more likely to persist when diversity declines (62). Related research has indicated that hosts with a high intrinsic rate of increase are both more ecologically resilient and reservoir competent (58). Other work has emphasized the idiosyncratic nature of particular disease/ecology relationships (63), and still other efforts have concluded that generalizations about the effect of biodiversity on disease transmission have been premature (64).…”