Dichotomous Keys Based on Cytogenetic Data for Triatomines Reported in Brazilian Regions with Outbreaks of Orally Transmitted Chagas Disease (Pernambuco and Rio Grande Do Norte)

From molecules to ecosystems: Insights into a network of interactions for a Chagas disease outbreak using Triatoma brasiliensis as natural samplers

Exploring the dynamics of disease transmission involves an understanding of complex interactions within the eco-epidemiologic framework. In the context of Chagas disease (CD), elements are mainly represented by the interactions among the pathogen, insect vector, host, humans and the environment. We performed quantitative and qualitative analyses on a dataset derived from 98 Triatoma brasiliensis infected by trypanosomatids, which were linked to a CD outbreak in the semi-arid region of northeastern Brazil. We extracted invertebrate-derived DNA (iDNA) from these insects, comprising 18 populations around the outbreak area, each indicative of various strata of anthropogenic influence. Food source (FS) diversity, representing potential parasite reservoirs, was determined through mitochondrial gene (cyt b) sequencing of vertebrates, and parasite genotyping was accessed using fluorescent amplified fragment barcodes (FFLB) of trypanosomatids. We also assessed the residents' awareness of breeding sites for CD vectors in the inspected houses. The quantification of Trypanosoma cruzi was estimated via real-time PCR and is denominated here as the average parasite load (PL) per insect (T. cruzi/intestinal unit). We aimed to address vector-parasite-host-environment interactions that were discussed based on their significance among the components. Notably, among the significant interactions, we observed that the PL in the insects was significantly influenced by FS. Infected insects that fed on the classic reservoir, Didelphis albiventris, and Galea spixii exhibited higher PLs, compared to those that fed on Kerodon rupestris (p < 0.04)-a primary host. While D. albiventris is already recognized as a synanthropic species, we propose that G. spixii may also be undergoing a synanthropic process. Conversely, domestic cats are frequently identified as FS in infected insects from the sylvatic environment, suggesting a possible change in their behavior towards a wild state. Therefore, we propose that neglected anthropogenic actions have facilitated the reciprocal (sylvatic-peridomestic) circulation of T. cruzi-especially noted for TcI because it was predominant in insects found in peridomestic environments. Residents are often unaware of the existence of insect breeding grounds near their homes, particularly when it involves the storage of materials without planning for use, such as piles of tiles, bricks and wood. Although indirect inferences about the interaction among vector-parasite-host-environment are still incipient, we highlight the potential use of vectors as natural samplers of biological and ecological components in transmitting the disease.

What Do You Need to Know before Studying Chagas Disease? A Beginner's Guide

Chagas disease is one of the most important tropical infections in the world and mainly affects poor people. The causative agent is the hemoflagellate protozoan Trypanosoma cruzi, which circulates among insect vectors and mammals throughout the Americas. A large body of research on Chagas disease has shown the complexity of this zoonosis, and controlling it remains a challenge for public health systems. Although knowledge of Chagas disease has advanced greatly, there are still many gaps, and it is necessary to continue generating basic and applied research to create more effective control strategies. The aim of this review is to provide up-to-date information on the components of Chagas disease and highlight current trends in research. We hope that this review will be a starting point for beginners and facilitate the search for more specific information.