Abstract
Background Triatoma dimidiata, currently the major Central American vector of Trypanosoma cruzi, the parasite that causes Chagas disease, inhabits caves throughout the region. This research investigates the possibility that cave dwelling T. dimidiata might transmit the parasite to humans and links the blood meal sources of cave vectors to cultural practices that differ among locations.Methodology/Principal FindingsWe determined the blood meal sources of twenty-four T. dimidiata collected from two locations in Guatemala and one in Belize where human interactions with the caves differ. Blood meal sources were determined by cloning and sequencing PCR products amplified from DNA extracted from the vector abdomen using primers specific for the vertebrate 12S mitochondrial gene. The blood meal sources were inferred by ≥99% identity with published sequences. We found 70% of cave-collected T. dimidiata positive for human DNA. The vectors had fed on 10 additional vertebrates with a variety of relationships to humans, including companion animal (dog), food animals (pig, sheep/goat), wild animals (duck, two bat, two opossum species) and commensal animals (mouse, rat). Vectors from all locations fed on humans and commensal animals. The blood meal sources differ among locations, as well as the likelihood of feeding on dog and food animals. Vectors from one location were tested for T. cruzi infection, and 30% (3/10) tested positive, including two positive for human blood meals.Conclusions/SignificanceCave dwelling Chagas disease vectors feed on humans and commensal animals as well as dog, food animals and wild animals. Blood meal sources were related to human uses of the caves. We caution that just as T. dimidiata in caves may pose an epidemiological risk, there may be other situations where risk is thought to be minimal, but is not.
Highlights
Humans have been attracted to caves for much of our history for purposes as varied as religious ceremonies to shelter
We challenge the assumption that cave-dwelling vectors are not important for human transmission by determining blood meal sources of vectors collected in caves from three locations that differ in the activities of humans at the caves, and link the results to cultural practices that differ among locations
Seventy percent of cave-collected vectors were positive for human DNA, and fed on 10 additional vertebrates with relationships to humans varying from companion animal, food animals, wild animals to commensal animals
Summary
Humans have been attracted to caves for much of our history for purposes as varied as religious ceremonies to shelter. In Guatemala people use caves for several cultural practices including religious ceremonies, tourism, and shelter [1]. In the department of Peten in northern Guatemala, caves are often used by hunters for sleeping and shelter from rain, especially in the rainy season. In northern Guatemala, caves in the department of Alta Verapaz are sacred places and sometimes the site of Mayan religious ceremonies; tourists visit some caves. This research investigates the possibility that cave dwelling T. dimidiata might transmit the parasite to humans and links the blood meal sources of cave vectors to cultural practices that differ among locations
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