Ecological Connectivity of Trypanosoma cruzi Reservoirs and Triatoma pallidipennis Hosts in an Anthropogenic Landscape with Endemic Chagas Disease

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.

Prehistoric earth oven facilities and the pathoecology of Chagas disease in the Lower Pecos Canyonlands

“…Seven species of rodent were collected, all of which had individuals that were infected. Ramsey et al (2012) found an ecological connectivity between sylvatic areas, ecotone between sylvatic and domestic areas, and domestic habitats that provided for reservoir species dispersal. They point out that in the modern world, human expansion of domestic environments into sylvatic cycles results in chronic Chagas disease infection.…”

“…The analysis of anthropogenic landscape change related to Chagas disease by Ramsey et al (2012) presents a modern example of ecological connectivity of Chagas disease with human development of the environment. These researchers addressed the basic question of how triatomines become reestablished in a Mexican village rapidly after a successful triatomine extermination program.…”

Landscape ecology of Trypanosoma cruzi in the southern Yucatan Peninsula

“…Recent studies on the ecological connectivity of vector and parasite host communities within anthropogenic landscapes are providing novel insights into the spatial epidemiology linked to T. cruzi transmission, vector population dynamics, and mammal host metacommunities (Ramsey et al, 2012;Gottdenker et al, 2014;Fernandez et al, 2014). Metacommunities resulting from habitat filtering in anthropogenic landscapes influence bloodmeal use by triatomines, and generally increase T. cruzi prevalence (Gottdenker et al, 2012;Ramsey et al, 2012;Gurtler et al, 2014). Furthermore, regional-scale phylogeographic studies of T. cruzi highlight the influence of sylvatic habitats surrounding human-transformed land as sources of parasite diversity (Ocana-Mayorga et al, 2010;Lima et al, 2014a).…”

“…Thebloodmeal source of all T. dimidiata was identified using PCR as previously described (Mota et al, 2007;Ramsey et al,2012). The proportion of bugs containing human blood was used to calculate the adjusted prevalence of single or mixed human bloodmeals in each habitat.…”

“…Extracted DNA was re-suspended in 80 µL of nuclease-free water, and maintained at 20°C prior to amplification protocols. All samples were first analyzed for the presence of T. cruzi using oligonucleotide primers from the conserved region of the kinetoplast minicircle, S34 5-ACA CCA ACC CCA ATC GAA CC-3 and S67 5-TGG TTT TGG GAG GGG SSK TC-3 (Sturm et al, 1989;Ramsey et al, 2012), resulting in a 125 bp product. PCR amplicons were separated on 3% agarose gel, stained with ethidium bromide and visualized under UV light.…”