We report Trypanosoma cruzi infection in wild and domestic mammals from three orally acquired Chagas disease outbreak areas in Brazil. Cachoeiro do Arari (Pará) displayed a panzootic scenery (positive mammals in all ecologic strata), and human cases were probably the consequence of their exposure within the sylvatic T. cruzi transmission cycle. In Navegantes (Santa Catarina), Didelphis spp. was the main reservoir host, given that 93% were infected. In Redenção (Ceará), Monodelphis domestica and Thrichomys laurentius were also important for parasite maintenance. TCI was present in the three studied areas. Additionally, Z3 was detected in an armadillo from Pará and TCII in a triatomine from Navegantes. Domestic animals showed a high seroprevalence and should be considered sentinels in surveillance programs. The importance of a reduction in wild mammalian fauna diversity and selection of suitable T. cruzi reservoir hosts are discussed as risk factors for the re-emergence of Chagas disease.
BackgroundThe aim of this work was to explore the potential risk of vector-borne Chagas disease in urban districts in northeastern Brazil, by analyzing the spatiotemporal distributions and natural infection rates with Trypanosoma cruzi of triatomine species captured in recent years. The main motivation of this work was an acute human case of Chagas disease reported in 2008 in the municipality of Sobral.Methodology/principal findingsWe analyzed data from community-based entomological surveillance carried out from 2010 to 2014. Triatomine natural T. cruzi infection was assessed by examination of insect feces by optical microscopy. Sites of triatomine capture were georeferenced through Google Earth and analyzed with ArcGIS. A total of 191 triatomines were collected, consisting of 82.2% Triatoma pseudomaculata, 7.9% Rhodnius nasutus, 5.8% T. brasiliensis, 3.7% Panstrongylus lutzi, and 0.5% P. megistus, with an overall natural infection index of 17.8%. Most infestations were reported in the districts of Dom José (36.2%), Padre Palhano (24.7%), and Alto do Cristo (10.6%). The overwhelming majority of insects (185/96.9%) were captured inside houses, and most insects tended to be collected in intermittent peaks. Moreover, captured triatomines tended to constitute colonies. The acute case reported in 2008 was found to be situated within a T. pseudomaculata hotspot.ConclusionThe triatomine collection events carried out by dwellers were aggregated in time and space into distinct foci, suggesting that insects are intermittently and artificially introduced into the city, possibly via accidental migration from their natural reservoirs. The relatively high T. cruzi infection rate indicates considerable circulation of the parasite in these areas, increasing the risk of vector-borne Chagas disease infection. These data suggest a need to strengthen epidemiological surveillance and integrate appropriate control actions targeting triatomines, T. cruzi reservoirs, and human populations. Our data also identify Chagas disease transmission as a hazard in urban areas of Sobral.
Land use changes and biodiversity loss critically disrupts ecosystem functioning and are major drivers of infectious disease outbreaks. Trypanosoma cruzi, the agent of Chagas disease, is a multi‐host parasite whose epidemiology has changed due to the expansion of anthropogenic activities over natural areas. We aimed to understand the ecological processes increasing parasite prevalence at the individual, the community and the landscape levels using the largest database on small mammal infection by T. cruzi in Brazil. We applied machine learning techniques and structural equation models to show that allometric traits and the relative abundance of rodents in the community were important predictors of infection risk, followed by variables associated with the landscape environmental quality. Natural vegetation cover change and the taxonomic and functional dimensions of biodiversity indirectly reduced infection through its effect on the abundance distribution and composition of host communities. According to our findings, approaches to biodiversity conservation and restoration based on the integration of social inclusion and human welfare would contribute to regulate the prevalence of T. cruzi in wild hosts, which may reduce overall transmission risk.
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