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.

The implementation of sustainable control strategies aimed at disrupting the transmission of vector-borne pathogens requires a comprehensive knowledge of the vector ecology in the different eco-epidemiological contexts, as well as the local pathogen transmission cycles and their dynamics. However, even when focusing only on one specific vector-borne disease, achieving this knowledge is highly challenging, as the pathogen may exhibit a high genetic diversity and multiple vector species or subspecies and host species may be involved. In addition, the development of the pathogen and the vectorial capacity of the vectors may be affected by their midgut and/or salivary gland microbiome. The recent advent of Next-Generation Sequencing (NGS) technologies has brought powerful tools that can allow for the simultaneous identification of all these essential components, although their potential is only just starting to be realized. We present a metabarcoding approach that can facilitate the description of comprehensive host-pathogen networks, integrate important microbiome and coinfection data, identify at-risk situations, and disentangle the transmission cycles of vector-borne pathogens. Please use Adobe Acrobat Reader to read this book chapter for free. Just open this same document with Adobe Reader. If you do not have it, you can download it here. You can freely access the chapter at the Web Viewer here. Vector-Borne Diseases -Recent Developments in Epidemiology and Control 2This powerful approach should be generalized to unravel the transmission cycles of any pathogen and their dynamics, which in turn will help the design and implementation of sustainable, effective, and locally adapted control strategies.

Homegardens are reservoirs of genetic resources. When native plant populations are compromised, traditional management of homegardens can be an effective means of conserving species and enhancing food security. Hylocereus undatus (dragonfruit) is a key species in homegardens but is rarely found in wild populations in the Yucatan. We analyzed management practices and genetic diversity of dragonfruit grown in homegardens in three climate regions (West, Central, and East) in the state of Yucatan, Mexico. Dragonfruit presence and reproductive phenology were documented via 2,660 surveys applied in seventeen municipalities. Eighty-nine semi-structured interviews were conducted to document dragonfruit management and use. Seventy-one specimens were collected among nine populations to characterize genetic diversity with DNA Inter Simple Sequence Repeats (ISSRs) markers. Dragonfruit was found in 12.4% of homegardens, propagated via cuttings (98%), received minimal agricultural management, and flowered and fruited in different seasons among regions. Its fruits were consumed fresh or as a beverage and different parts of the plants were used to treat dysentery, kidney stones, hair loss, and gastritis. Genetic diversity among regions was moderate (PLP [polymorphic loci] = 25.1 to 53.3%; He [expected heterozygosity] = 0.075 to 0.138), but the polymorphism information content (PIC) values were at the most 20% lower than those estimated from an ex situ germplasm collection of Hylocereus spp. A Bayesian assignment analysis identified two genetic lineages (K = 2): one in the West and East regions and another in the West and Central regions. Genetic differentiation Jaccard indexes among accessions from all homegardens were similar to those found among wild accessions from Mexico. We conclude, therefore, that homegardens in Yucatan are important in conserving the regional biocultural heritage of dragonfruit.