Background Trypanosoma cruzi is the causative agent of Chagas disease. Due to its genetic diversity has been classified into six Discrete Typing Units (DTUs) in association with transmission cycles. In Colombia, natural T. cruzi infection has been detected in 15 triatomine species. There is scarce information regarding the infection rates, DTUs and feeding preferences of secondary vectors. Therefore, the aim of this study was to determine T. cruzi infection rates, parasite DTU, ecotopes, insect stages, geographical location and bug feeding preferences across six different triatomine species.MethodsA total of 245 insects were collected in seven departments of Colombia. We conducted molecular detection and genotyping of T. cruzi with subsequent identification of food sources. The frequency of infection, DTUs, TcI genotypes and feeding sources were plotted across the six species studied. A logistic regression model risk was estimated with insects positive for T. cruzi according to demographic and eco-epidemiological characteristics.ResultsWe collected 85 specimens of Panstrongylus geniculatus, 77 Rhodnius prolixus, 37 R. pallescens, 34 Triatoma maculata, 8 R. pictipes and 4 T. dimidiata. The overall T. cruzi infection rate was 61.2% and presented statistical associations with the departments Meta (OR: 2.65; 95% CI: 1.69–4.17) and Guajira (OR: 2.13; 95% CI: 1.16–3.94); peridomestic ecotope (OR: 2.52: 95% CI: 1.62–3.93); the vector species P. geniculatus (OR: 2.40; 95% CI: 1.51–3.82) and T. maculata (OR: 2.09; 95% CI: 1.02–4.29); females (OR: 2.05; 95% CI: 1.39–3.04) and feeding on opossum (OR: 3.15; 95% CI: 1.85–11.69) and human blood (OR: 1.55; 95% CI: 1.07–2.24). Regarding the DTUs, we observed TcI (67.3%), TcII (6.7%), TcIII (8.7%), TcIV (4.0%) and TcV (6.0%). Across the samples typed as TcI, we detected TcIDom (19%) and sylvatic TcI (75%). The frequencies of feeding sources were 59.4% (human blood); 11.2% (hen); 9.6% (bat); 5.6% (opossum); 5.1% (mouse); 4.1% (dog); 3.0% (rodent); 1.0% (armadillo); and 1.0% (cow).ConclusionsNew scenarios of T. cruzi transmission caused by secondary and sylvatic vectors are considered. The findings of sylvatic DTUs from bugs collected in domestic and peridomestic ecotopes confirms the emerging transmission scenarios in Colombia.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1907-5) contains supplementary material, which is available to authorized users.

Villavicencio, the capital city of the Department of Meta, Colombia, is at high risk for the urbanization of malaria because of the region's ecological conditions, as well as the permanent presence of infected human populations arriving from rural areas. From August to November 2002 and in April 2003, anopheline collections were undertaken in the area. Isofamilies were obtained from 331 wild females, which were then recorded according to their abundance as follows: Anopheles marajoara, Anopheles rangeli, Anopheles braziliensis, Anopheles darlingi, and Anopheles apicimacula. Anopoheles darlingi showed the highest biting activity (3.0) between 1800 and 1900 h. Forty-five breeding places were sampled, 64% of which were fish ponds, 6.7% flooded meadows, and 6.7% drainpipes, with these being the most representative locations. All sampled breeding sites were positive for anophelines. Anopheles marajoara could play an important role as an auxiliary vector in Villavicencio's urban area. Control measures should be aimed at weeding the marginal areas around fish ponds and at evaluating the use of impregnated bed-nets.

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...

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Patterns of malaria cases were compared between the department of Meta and the municipality of Puerto Gaitán, Colombia, to examine temporal change in malaria from 2005-2010. During this time frame in Meta the mean ratio was 2.53; in contrast, in Puerto Gaitán it was 1.41, meaning that a surprisingly high proportion of Plasmodium falciparum cases were reported from this municipality. A detailed analysis of data from Puerto Gaitán for 2009 and 2010 detected a significant difference (χ2, p < 0.001) in the distribution of plasmodia, with Plasmodium vivax more prevalent in 2009 and P. falciparum in 2010. Males had the highest number of cases but there was no difference in the distribution of cases between sexes and years. In both years, for both sexes, people 16-40 accounted for the majority of cases (58.9% in 2009; 60.4% in 2010). There were significant differences in the distribution of both P. vivax (χ2, p < 0.01) and P. falciparum cases (χ2, p < 0.05) by geographic setting (urban vs. non-urban) between years. Urban cases of both P. vivax and P. falciparum are recorded in this study for the first time in Puerto Gaitán, possibly the result of area wide displacement and migration due to armed conflict.

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Trypanosoma cruzi, the causal agent of Chagas disease, is mainly transmitted by insects of the Triatominae subfamily. In Colombia, there are 26 triatomine species, and 16 of them are naturally infected with the parasite. The parasite loads of naturally infected vectors can be significant in targeting specific species that can affect the epidemiology of the disease. Studying their ecology and behavior is vital to understand their role in T. cruzi transmission dynamics. We evaluated the parasite loads of 182 field-collected triatomines corresponding to 10 species in 13 departments across Colombia. We standardized a methodology to quantify T. cruzi DNA in these insects. We obtained a LOD (limit of detection) of 3.05 p-eq/mL. The 82% of triatomines we evaluated were positive for T. cruzi infection, with loads ranging from hundreds to millions of equivalent parasites per milliliter. Panstrongylus geniculatus, Rhodnius prolixus, and Triatoma dimidiata were the species with the highest loads of T. cruzi; however, other species whose role as vectors is still unknown were also found with high loads of parasites. Our results suggest the relevance of secondary species for T. cruzi transmission in Colombia. We hope our data can help improve entomological surveillance and vector control programs in the country and the region.