Abstract
BackgroundThe demographic transition of populations from rural areas to large urban centers often results in a disordered occupation of forest remnants and increased economic pressure to develop high-income buildings in these areas. Ecological and socioeconomic factors associated with these urban transitions create conditions for the potential transmission of infectious diseases, which was demonstrated for Chagas disease.Methodology/Principal FindingsWe analyzed 930 triatomines, mainly Triatoma tibiamaculata, collected in artificial and sylvatic environments (forests near houses) of a suburban area of the city of Salvador, Bahia State, Brazil between 2007 and 2011. Most triatomines were captured at peridomiciles. Adult bugs predominated in all studied environments, and nymphs were scarce inside houses. Molecular analyses of a randomly selected sub-sample (n=212) of triatomines showed Trypanosoma cruzi infection rates of 65%, 50% and 56% in intradomestic, peridomestic and sylvatic environments, respectively. We detected the T. cruzi lineages I and II and mixed infections. We also showed that T. tibiamaculata fed on blood from birds (50%), marsupials (38%), ruminants (7%) and rodents (5%). The probability of T. cruzi infection was higher in triatomines that fed on marsupial blood (odds ratio (OR) = 1.95, 95% confidence interval (CI) = 1.22-3.11). Moreover, we observed a protective effect against infection in bugs that fed on bird blood (OR = 0.43, 95% CI = 0.30-0.73).Conclusions/SignificanceThe frequent invasion of houses by infected triatomines indicates a potential risk of T. cruzi transmission to inhabitants in this area. Our results reinforce that continuous epidemiological surveillance should be performed in areas where domestic transmission is controlled but enzootic transmission persists.
Highlights
The demographic transition of populations from rural areas to large urban centers often results in the development of slums, disordered occupation of forest remnants, parks, and protected areas, and increased economic pressure to develop high-income buildings in these same areas
We studied the spatial distribution, natural infections by Trypanosoma cruzi and feeding patterns of triatomines in a suburban area of Salvador, Bahia State, Brazil between 2007 and 2011
Triatoma tibiamaculata was collected in sylvatic, peridomestic and domestic habitats, and a high T. cruzi infection rate was established for triatomines that fed on blood from birds, marsupials, ruminants and rodents
Summary
The demographic transition of populations from rural areas to large urban centers often results in the development of slums, disordered occupation of forest remnants, parks, and protected areas, and increased economic pressure to develop high-income buildings in these same areas. Anthropogenic landscape disturbances can increase triatomine abundance and their rates of infection with T. cruzi, which indicates that forest remnants may be sources for vector populations within disturbed areas [16,17]. These processes, coupled with socioeconomic factors and triatomine attraction to artificial lights, may influence the invasion of Chagas disease vectors in environments near human populations [18,19,20]. The demographic transition of populations from rural areas to large urban centers often results in a disordered occupation of forest remnants and increased economic pressure to develop high-income buildings in these areas. Ecological and socioeconomic factors associated with these urban transitions create conditions for the potential transmission of infectious diseases, which was demonstrated for Chagas disease.
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