Abstract
BackgroundIn the Yucatán Peninsula, Mexico, Triatoma dimidiata is the main vector of Trypanosoma cruzi, the causative agent of Chagas disease. Little effort has been made to identify blood meal sources of T. dimidiata in natural conditions in this region, although this provides key information to disentangle T. cruzi transmission cycles and dynamics and guide the development of more effective control strategies. We identified the blood meals of a large sample of T. dimidiata bugs collected in different ecotopes simultaneously with the assessment of bug infection with T. cruzi, to disentangle the dynamics of T. cruzi transmission in the region.MethodsA sample of 248 T. dimidiata bugs collected in three rural villages and in the sylvatic habitat surrounding these villages was used. DNA from each bug midgut was extracted and bug infection with T. cruzi was assessed by PCR. For blood meal identification, we used a molecular assay based on cloning and sequencing following PCR amplification with vertebrate universal primers, and allowing the detection of multiple blood meals in a single bug.ResultsOverall, 28.7% of the bugs were infected with T. cruzi, with no statistical difference between bugs from the villages or from sylvatic ecotopes. Sixteen vertebrate species including domestic, synanthropic and sylvatic animals, were identified as blood meal sources for T. dimidiata. Human, dog and cow were the three main species identified, in bugs collected in the villages as well as in sylvatic ecotopes. Importantly, dog was highlighted as the main blood meal source after human. Dog was also the most frequently identified animal together with human within single bugs, and tended to be associated with the infection of the bugs.ConclusionsDog, human and cow were identified as the main mammals involved in the connection of sylvatic and domestic transmission cycles in the Yucatán Peninsula, Mexico. Dog appeared as the most important animal in the transmission pathway of T. cruzi to humans, but other domestic and synanthropic animals, which most were previously reported as important hosts of T. cruzi in the region, were evidenced and should be taken into account as part of integrated control strategies aimed at disrupting parasite transmission.
Highlights
In the Yucatán Peninsula, Mexico, Triatoma dimidiata is the main vector of Trypanosoma cruzi, the causative agent of Chagas disease
Simultaneously with the assessment of the infection of the triatomine bugs with T. cruzi, we identified the blood meal sources in a large sample of T. dimidiata collected in different ecotopes using a molecular assay allowing for the identification of multiple blood meals in a single bug [17,18,19,20] to better understand the dynamics of T. cruzi transmission to humans in the region
It is clear that achievement of this goal will be postponed, because of the role played by intrusive triatomine species on intra-domiciliary transmission, and that innovative control strategies, based on a comprehensive understanding of the ecology of the vectors and of local T. cruzi transmission cycles and their dynamics, are needed to achieve such an ambitious target [10, 32, 33]
Summary
In the Yucatán Peninsula, Mexico, Triatoma dimidiata is the main vector of Trypanosoma cruzi, the causative agent of Chagas disease. Trypanosoma cruzi is transmitted to more than 180 mammal species (including humans) by blood-sucking bugs called triatomines, from which 31 species are currently reported in Mexico [2, 3] In this country, active transmission is reported in most of the territory and the most recent estimates suggest a national seroprevalence of 3.38%, suggesting that around four million people carry the parasite in the country, and highlighting the urgency of establishing Chagas disease surveillance and control as a key national public health priority in Mexico [4]. While T. dimidiata may colonize houses in some regions, it presents an intrusive behavior in multiple regions and most in Yucatán In this region, located in southern Mexico, it lives mainly in sylvatic ecotopes and to a lesser extent in peridomestic habitats, but frequently enters inside homes, on a seasonal basis, without establishing large colonies [6,7,8]. Vector control based on massive insecticide spraying has limited efficacy and is not sustainable [9, 10] while alternative strategies, based for example on Ecohealth/One Health approaches are giving promising results [11, 12]
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