Lizards and rabbits may increase Chagas infection risk in the Mediterranean-type ecosystem of South America

Esteban San Juan,Nicol Quiroga,Raúl Araya-Donoso,Carezza Botto-Mahan,Andrea Yáñez-Meza,Alejandra Sandoval-Rodríguez

doi:10.1038/s41598-020-59054-8

Abstract

Studies of host-parasite relationships largely benefit from adopting a multifactorial approach, including the complexity of multi-host systems and habitat features in their analyses. Some host species concentrate most infection and contribute disproportionately to parasite and vector population maintenance, and habitat feature variation creates important heterogeneity in host composition, influencing infection risk and the fate of disease dynamics. Here, we examine how the availability of specific groups of hosts and habitat features relate to vector abundance and infection risk in 18 vector populations along the Mediterranean-type ecosystem of South America, where the kissing bug Mepraia spinolai is the main wild vector of the parasite Trypanosoma cruzi, the etiological agent of Chagas disease. For each population, data on vectors, vertebrate host availability, vegetation, precipitation, and temperature were collected and analyzed. Vector abundance was positively related to temperature, total vegetation, and European rabbit availability. Infection risk was positively related to temperature, bromeliad cover, and reptile availability; and negatively to the total domestic mammal availability. The invasive rabbit is suggested as a key species involved in the vector population maintenance. Interestingly, lizard species –a group completely neglected as a potential reservoir–, temperature, and bromeliads were relevant factors accounting for infection risk variation across populations.

Highlights

IntroductionWe assess how specific host assemblages and habitat features relate to vector abundance and infection risk (measured as infected vector abundance) in a range of abiotic conditions across populations
In this study, we assess how specific host assemblages and habitat features relate to vector abundance and infection risk in a range of abiotic conditions across populations
In this study we address the following questions: (1) Do reptiles, birds, and mammals influence vector abundance and infection risk at the regional scale? (2) To what extent are these effects - if any - modulated by the habitat features? (3) What is the importance of non-native mammal species on vector abundance and infection risk across localities?

Summary

Introduction

We assess how specific host assemblages and habitat features relate to vector abundance and infection risk (measured as infected vector abundance) in a range of abiotic conditions across populations. We focus on a system composed of the flagellated protozoan parasite Trypanosoma cruzi (the causative agent of Chagas disease), its hematophagous triatomine vector (kissing bugs), and vertebrate assemblages that include reptiles, birds, and native and non-native mammals from the Mediterranean-type ecosystem of South America (Chile). The first goal of our study was to identify the vertebrate assemblages that influence vector abundance and the maintenance of the protozoan T. cruzi at regional scale Because habitat features such as temperature, precipitation and vegetation cover, often affect host and insect vector demographic parameters such as survival and reproductive rates[21,22,23], the infection risk found in natural populations may be determined by variation in these factors[24,25].

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