Methods to determine blood-meal sources of hematophagous Triatominae bugs (Chagas disease vectors) are serological or based on PCR employing species-specific primers or heteroduplex analysis, but these are expensive, inaccurate, or problematic when the insect has fed on more than one species. To solve those problems, we developed a technique based on HRM analysis of the mitochondrial gene cytochrome B (Cyt b). This technique recognized 14 species involved in several ecoepidemiological cycles of the transmission of Trypanosoma cruzi and it was suitable with DNA extracted from intestinal content and feces 30 days after feeding, revealing a resolution power that can display mixed feedings. Field samples were analyzed showing blood meal sources corresponding to domestic, peridomiciliary and sylvatic cycles. The technique only requires a single pair of primers that amplify the Cyt b gene in vertebrates and no other standardization, making it quick, easy, relatively inexpensive, and highly accurate.

Oral transmission of Trypanosoma cruzi has gained relevance because of its association with high morbidity and lethality rates. This transmission route is responsible for maintaining the infection of the parasite in sylvatic cycles, and human cases have been associated mainly with the consumption of food contaminated with triatomine feces or didelphid secretions. Several ecological changes allow the intrusion of sylvatic reservoirs and triatomines to the domestic environments with subsequent food contamination. Here, high-resolution molecular tools were used to detect and genotype T. cruzi across humans, reservoirs, and insect vectors in 2 acute outbreaks of presumptive oral transmission in eastern Colombia.Keywords. Chagas disease; oral transmission; outbreaks; triatomines; Trypanosoma cruzi; opossums; canines; food.Oral transmission of Trypanosoma cruzi is considered ancient, allowing the circulation and maintenance of the parasite in the sylvatic cycle of transmission. T. cruzi has been classified into 6 discrete typing units (DTUs), TcI-TcVI, and, within TcI, into 2 genotypes (domestic TcI [TcI Dom ] and sylvatic TcI). In humans, this mechanism has been described in >1000 cases corresponding to 138 outbreaks, with a fatality rate of 8%-35% across Latin America [1,2]. In Colombia, between 1992 and 2009, 11 outbreaks were reported, with a lethality rate of 16.0% [3]. In 2014, 2 outbreaks occurred in the Colombian Orinoco region.The aim of this study was to determine the possible sources of oral transmission, by using molecular tools, during the outbreaks that occurred in the municipalities of Restrepo, Meta Department, and Paz de Ariporo, Casanare Department. METHODSA total of 70 patients with suspected T. cruzi oral infection, along with 39 samples from reservoir organisms (opossums and canines) and 23 samples from triatomines (Panstrongylus geniculatus, Rhodnius pictipes, and Rhodnius prolixus) during the 2 outbreaks were included. Patients were confirmed as infected, using direct parasitological tests (thick blood smears), serological tests (trypomastigote excreted-secreted antigen [TESA] [5,6]. Finally, in all qPCR-positive samples, amplification and analysis by Microsat (a program for microsatellite analysis) was performed using 7 microsatellite markers [7]. RESULTS Restrepo OutbreakThis outbreak occurred in a family comprising 4 adults and 1 child, who visited Restrepo, including a farm, which contains forests and savannas, as well as some restaurants located along the road in Cumaral municipality, between February 13 and 16, 2014. The family returned to Bogota (the capital of Colombia) afterward, where the 4 adults were hospitalized for fever and edema. Thick blood smears were positive in 2 of 4 symptomatic patients. Results of conventional serological analyses, TESA blots, and molecular tests were positive for the 4 symptomatic patients. The median parasite load was 6.2 equivalent parasites/mL. The child was asymptomatic and had negative results of all diagnostic tests (Supplementary Table 1).The fi...

Triatomines are the vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Although Triatoma and Rhodnius are the most-studied vector genera, other triatomines, such as Panstrongylus, also transmit T. cruzi, creating new epidemiological scenarios. Panstrongylus has at least 13 reported species but there is limited information about its intraspecific genetic variation and patterns of diversification. Here, we begin to fill this gap by studying populations of P. geniculatus from Colombia and Venezuela and including other epidemiologically important species from the region. We examined the pattern of diversification of P. geniculatus in Colombia using mitochondrial and nuclear ribosomal data. Genetic diversity and differentiation were calculated within and among populations of P. geniculatus. Moreover, we constructed maximum likelihood and Bayesian inference phylogenies and haplotype networks using P. geniculatus and other species from the genus (P. megistus, P. lignarius, P. lutzi, P. tupynambai, P. chinai, P. rufotuberculatus and P. howardi). Using a coalescence framework, we also dated the P. geniculatus lineages. The total evidence tree showed that P. geniculatus is a monophyletic species, with four clades that are concordant with its geographic distribution and are partly explained by the Andes orogeny. However, other factors, including anthropogenic and eco-epidemiological effects must be investigated to explain the existence of recent geographic P. geniculatus lineages. The epidemiological dynamics in structured vector populations, such as those found here, warrant further investigation. Extending our knowledge of P. geniculatus is necessary for the accurate development of effective strategies for the control of Chagas disease vectors.

Background The transmission dynamics of leishmaniasis are complex. There is also a lack of information about the ecological relationships between the vector/host/parasite at a more local and specific level. The Andean region concentrates more than 50% of Colombia’s cutaneous leishmaniasis (CL) cases. The study of the ecological interactions of sand flies through the identification of blood sources has provided information on the female’s opportunistic behavior, feeding on various hosts. Therefore, this study aimed to determine sand flies’ ecological interactions with Leishmania parasites and their blood sources in an endemic area of CL. Results A total of 4,621 sand flies were collected, comprising 20 species, in which the most abundant were Nyssomyia yuilli yuilli (55.4%), Psychodopygus ayrozai (14.5%) and Ps. panamensis (13.4%). Sequences of 12S gene fragment were analyzed using the BLASTn search tool. Blood-meal source identification was successfully performed for 47 sand flies, detecting seven vertebrate species, human and armadillo being the most frequent. Leishmania DNA was amplified in four female pools, constituted by Ny. yuilli yuilli and Ps. ayrozai, and the identification through RFLP detected Leishmania (Viannia) panamensis in the positive pools. Conclusions The interactions between the sand fly species, local mammalian fauna and the Leishmania parasite in this active focus of CL, provide evidence of the potential role of two different species in the maintenance of the parasite transmission, important information for the understanding of the ecoepidemiology and transmission dynamics of the disease in Andean endemic areas. However its necessary further evaluations of the vector and host competence in the transmission and maintenance of Leishmania spp, in these complex and diverse areas.