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Abstract. Characteristics of Trypanosoma cruzi infection were studied in a rural area of the eastern plains of Colombia. Using enzyme-linked immunosorbent assay and indirect fluorescent-antibody tests, the infection was determined in 11.6% of the inhabitants of 142 dwellings. During 6 months of community surveillance, in 42.3% dwellings, 609 triatomines were collected (597 Rhodnius prolixus and seven, three, one, and one of Panstrongylus geniculatus, Psammolestes arturi, Eratyrus mucronatus, and Triatoma maculata, respectively). Rhodnius prolixus was found in 80% peridomiciliary Attalea butyracea palms examined with baited traps, and its infection with T. cruzi was 30% and 38.5% in dwellings and palms, respectively. Trypanosoma cruzi was isolated in five of 35 triatomines and in one of 24 dogs. The blood of domestic and wild animals was identified in triatomines collected in the intradomicile and in palms. These results support the extension of the wild cycle of T. cruzi to human dwellings and the characterization of a new scenario for transmission in Colombia.Trypanosoma cruzi infection continues to affect nearly 6 million people in 21 countries of the Americas 1 despite the success of control programs against domestic triatomines. 2There are zones where dwellings are infested by other species of Triatominae with peridomiciliary and wild ecotopes. In the Amazon, some of the more than 27 wild species described, principally of the genus Rhodnius, have made incursions into dwellings, with the risk of infecting human populations. 3In Colombia, the Andean region in the eastern zone below 2,000 m above sea level has been considered endemic for Chagas disease because of the high degree of domiciliary infestation, wide dispersion, and the high densities of Rhodnius prolixus.4,5 A decade after the adoption of a government program to control domiciliary triatomines, in our observation, this species has been controlled. However, another transmission scenario has begun to be known with checking of the wild cycle in peridomiciliary palms as a transmission risk factor in the departments of the eastern plains 6 and the reporting of high prevalence rates of human infection with T. cruzi.7 This study was conducted for the purpose of clarifying the epidemiological characteristics of this scenario in this region.In December 2008, the prevalence of T. cruzi infection was evaluated in the inhabitants of 142 dwellings in the department of Casanare, dispersed in rural areas of the municipalities of Maní (04°49′02″N/72°17′19″W) and Aguazul (05°10′23″N/ 72°33′17″W), which were fumigated by the program of VectorTransmitted Diseases (Enfermedades Transmitidas por Vectores [ETV], in Spanish) in that department. This territory corresponds to the alluvial and eolic plains of the Orinoquía, composed of flooded savannas with herbaceous and graminaceous vegetation in the humid warm thermal floor, with an average temperature of 25-27°C and an annual rainfall of 2,400-2,600 mm (Figure 1).The dwellings are constructed with brick walls, cement, ti...

Chagas disease is a severe public health problem in Latin-American countries. In Colombia, the predominance of Trypanosoma cruzi I has been described in the literature, with a broad heterogeneity between strains. However, most of the studies carried out centered on isoenzyme analysis, with a smaller number that focus on other molecular methods. In this report, we discuss the results of a molecular analysis of T. cruzi I strains, isolated from the domestic cycle, from the department of Santander, one of the territorial divisions where the prevalence of infection is highest. Internal transcribed spacer-restriction fragment length polymorphism and random amplification of polymorphic DNA were used to characterize 16 strains from human and vector (Triatominae) hosts. The data reveal a clustering based on the biological origin. Human and vector strains grouped separately; however, three vector strains clustered together with human strains. These results indicate that genetic differences exist in the strains that infect both hosts. We conclude that T. cruzi I populations in the domestic cycle of transmission of Chagas disease in Santander are heterogeneous and are composed of different clones. The epidemiological and biological implications are discussed.

One hundred twenty Rhodnius prolixus (Stal) (Hemiptera: Reduviidae) specimens from 6 Colombian Departments and 1 Venezuelan State had 594-bp of the mitochondrial cytochrome-b gene sequenced to improve the understanding of evolutionary processes that shape the main vector of Chagas disease. The levels of genetic diversity for this species were low-medium with reference to other bugs. The genetic heterogeneity among the populations was very limited which means there has been extensive gene flow and/or very recent split processes. The overall sample as well as some individual populations showed evidence of recent population expansions (with the exception of Arauca, which yielded evidence of a bottleneck for a mismatch distribution). This expansion (11,000 or 2000-25,000 year ago depending of two procedures employed) coincides with the ending of the last intense glacial conditions during the Pleistocene and the beginning of the Holocene that had a warmer and wetter climate. Some of our autocorrelation analyses (AIDA and Genetic Landscape Interpolation Analysis) indicated local patches of high genetic similarity but no globally significant spatial structure. We did show an original haplotype distributed throughout the entirety of the geographical area studied.