Abstract
Traditional methods for Chagas disease prevention are targeted at domestic vector reduction, as well as control of transfusion and maternal-fetal transmission. Population connectivity of Trypanosoma cruzi-infected vectors and hosts, among sylvatic, ecotone and domestic habitats could jeopardize targeted efforts to reduce human exposure. This connectivity was evaluated in a Mexican community with reports of high vector infestation, human infection, and Chagas disease, surrounded by agricultural and natural areas. We surveyed bats, rodents, and triatomines in dry and rainy seasons in three adjacent habitats (domestic, ecotone, sylvatic), and measured T. cruzi prevalence, and host feeding sources of triatomines. Of 12 bat and 7 rodent species, no bat tested positive for T. cruzi, but all rodent species tested positive in at least one season or habitat. Highest T. cruzi infection prevalence was found in the rodents, Baiomys musculus and Neotoma mexicana. In general, parasite prevalence was not related to habitat or season, although the sylvatic habitat had higher infection prevalence than by chance, during the dry season. Wild and domestic mammals were identified as bloodmeals of T. pallidipennis, with 9% of individuals having mixed human (4.8% single human) and other mammal species in bloodmeals, especially in the dry season; these vectors tested >50% positive for T. cruzi. Overall, ecological connectivity is broad across this matrix, based on high rodent community similarity, vector and T. cruzi presence. Cost-effective T. cruzi, vector control strategies and Chagas disease transmission prevention will need to consider continuous potential for parasite movement over the entire landscape. This study provides clear evidence that these strategies will need to include reservoir/host species in at least ecotones, in addition to domestic habitats.
Highlights
Chagas disease, caused principally by the vector transmission of Trypanosoma cruzi, is widespread and endemic in Latin America from southern United States to Argentina, with emerging nonvector transmission in other North American [1] and European countries [2]
Triatomine and mammal surveys In all, 185 T. pallidipennis and two T. barberi individuals were collected in this study; the latter species is not included in our analyses, since no bloodmeals were obtained from either specimen
Triatoma pallidipennis collection success was highest in domestic habitats in the rainy season, with a non-significant decrease during the dry season though the collection method for the domestic habitat was direct, as compared with indirect for the ecotone and sylvatic areas (Table 1)
Summary
Chagas disease, caused principally by the vector transmission of Trypanosoma cruzi, is widespread and endemic in Latin America from southern United States to Argentina, with emerging nonvector transmission in other North American [1] and European countries [2]. At least formerly the primary vector responsible for Chagas disease transmission in many South American countries, is almost entirely domestic over its distribution, genetically isolated from sylvatic populations that persist only in a few regions [4,5,6]. Triatoma pallidipennis has been incriminated as one of the most important vector species for human T. cruzi infections in Mexico [13]
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