Comparative proteomic analysis of the hemolymph and salivary glands of Rhodnius prolixus and R. colombiensis reveals candidates associated with differential lytic activity against Trypanosoma cruzi Dm28c and T. cruzi Y.

BACKGROUND: Immune response of triatomines plays an important role in the success or failure of transmission of T. cruzi. Studies on parasite-vector interaction have shown the presence of trypanolytic factors and have been observed to be differentially expressed among triatomines, which affects the transmission of some T. cruzi strains or DTUs (Discrete Typing Units). METHODOLOGY/PRINCIPAL FINDINGS: Trypanolytic factors were detected in the hemolymph and saliva of R. prolixus against epimastigotes and trypomastigotes of the Y strain (T. cruzi II). To identify the components of the immune response that could be involved in this lytic activity, a comparative proteomic analysis was carried out, detecting 120 proteins in the hemolymph of R. prolixus and 107 in R. colombiensis. In salivary glands, 1103 proteins were detected in R. prolixus and 853 in R. colombiensis. A higher relative abundance of lysozyme, prolixin, nitrophorins, and serpin as immune response proteins was detected in the hemolymph of R. prolixus. Among the R. prolixus salivary proteins, a higher relative abundance of nitrophorins, lipocalins, and triabins was detected. The higher relative abundance of these immune factors in R. prolixus supports their participation in the lytic activity on Y strain (T. cruzi II), but not on Dm28c (T. cruzi I), which is resistant to lysis by hemolymph and salivary proteins of R. prolixus due to mechanisms of evading oxidative stress caused by immune factors. CONCLUSIONS/SIGNIFICANCE: The lysis resistance observed in the Dm28c strain would be occurring at the DTU I level. T. cruzi I is the DTU with the greatest geographic distribution, from the south of the United States to central Chile and Argentina, a distribution that could be related to resistance to oxidative stress from vectors. Likewise, we can say that lysis against strain Y could occur at the level of DTU II and could be a determinant of the vector inability of these species to transmit T. cruzi II. Future proteomic and transcriptomic studies on vectors and the interactions of the intestinal microbiota with parasites will help to confirm the determinants of successful or failed vector transmission of T. cruzi DTUs in different parts of the Western Hemisphere.

High-throughput analysis of the Trypanosoma cruzi minicirculome (mcDNA) unveils structural variation and functional diversity.

Trypanosoma cruzi causes Chagas disease and has a unique extranuclear genome enclosed in a structure called the kinetoplast, which contains circular genomes known as maxi- and minicircles. While the structure and function of maxicircles are well-understood, many aspects of minicircles remain to be discovered. Here, we performed a high-throughput analysis of the minicirculome (mcDNA) in 50 clones isolated from Colombia's diverse T. cruzi I populations. Results indicate that mcDNA comprises four diverse subpopulations with different structures, lengths, and numbers of interspersed semi-conserved (previously termed ultra-conserved regions mHCV) and hypervariable (mHVPs) regions. Analysis of mcDNA ancestry and inter-clone differentiation indicates the interbreeding of minicircle sequence classes is placed along diverse strains and hosts. These results support evidence of the multiclonal dynamics and random bi-parental segregation. Finally, we disclosed the guide RNA repertoire encoded by mcDNA at a clonal scale, and several attributes of its abundance and function are discussed.

Genome plasticity driven by aneuploidy and loss of heterozygosity in Trypanosoma cruzi.

Trypanosoma cruzi the causative agent of Chagas disease shows a marked genetic diversity and divided into at least six Discrete Typing Units (DTUs). High intra genetic variability has been observed in the TcI DTU, the most widely distributed DTU, where patterns of genomic diversity can provide information on ecological and evolutionary processes driving parasite population structure and genome organization. Chromosomal aneuploidies and rearrangements across multigene families represent an evidence of T. cruzi genome plasticity. We explored genomic diversity among 18 Colombian T. cruzi I clones and 15 T. cruzi I South American strains. Our results confirm high genomic variability, heterozygosity and presence of a clade compatible with the TcIdom genotype, described for strains from humans in Colombia and Venezuela. TcI showed high structural plasticity across the geographical region studied. Differential events of whole and segmental aneuploidy (SA) along chromosomes even between clones from the same strain were found and corroborated by the depth and allelic frequency. We detected loss of heterozygosity (LOH) events in different chromosomes, however, the size and location of segments under LOH varied between clones. Genes adjacent to breakpoints were evaluated, and retrotransposon hot spot genes flanked the beginning of segmental aneuploidies. Our results suggest that T. cruzi genomes, like those of Leishmania, may have a highly unstable structure and there is now an urgent need to design experiments to explore any potential adaptive role for the plasticity observed.

Transcriptional remodeling during metacyclogenesis in Trypanosoma cruzi I.

Metacyclogenesis is one of the most important processes in the life cycle of Trypanosoma cruzi. In this stage, noninfective epimastigotes become infective metacyclic trypomastigotes. However, the transcriptomic changes that occur during this transformation remain uncertain. Illumina RNA-sequencing of epimastigotes and metacyclic trypomastigotes belonging to T. cruzi DTU I was undertaken. Sequencing reads were aligned and mapped against the reference genome, differentially expressed genes between the two life cycle stages were identified, and metabolic pathways were reconstructed. Gene expression differed significantly between epimastigotes and metacyclic trypomastigotes. The cellular pathways that were mostly downregulated during metacyclogenesis involved glucose energy metabolism (glycolysis, pyruvate metabolism, the Krebs cycle, and oxidative phosphorylation), amino acid metabolism, and DNA replication. By contrast, the processes where an increase in gene expression was observed included those related to autophagy (particularly Atg7 and Atg8 transcripts), corroborating its importance during metacyclogenesis, endocytosis, by an increase in the expression of the AP-2 complex subunit alpha, protein processing in the endoplasmic reticulum and meiosis. Study findings indicate that in T. cruzi metacyclic trypomastigotes, metabolic processes are decreased, and expression of genes involved in specific cell cycle processes is increased to facilitate transformation to this infective stage.

Slight temperature changes cause rapid transcriptomic responses in Trypanosoma cruzi metacyclic trypomastigotes.

BACKGROUND: Severe changes in temperature can affect the behavior and ecology of some infectious agents. Trypanosoma cruzi is a protozoan that causes Chagas disease. This parasite has high genetic variability and can be divided into six discrete typing units (DTUs). Trypanosoma cruzi also has a complex life-cycle, which includes the process of metacyclogenesis when non-infective epimastigote forms are differentiated into infective metacyclic trypomastigotes (MT). Studies in triatomines have shown that changes in temperature also affect the number and viability of MT. METHODS: The objective of this study was to evaluate how temperature affects the transcriptional profiles of T. cruzi I and II (TcI and TcII) MT by exposing parasites to two temperatures (27 °C and 28 °C) and comparing those to normal culture conditions at 26 °C. Subsequently, RNA-seq was conducted and differentially expressed genes were quantified and associated to metabolic pathways. RESULTS: A statistically significant difference was observed in the number of MT between the temperatures evaluated and the control, TcII DTU was not strongly affected to exposure to high temperatures compared to TcI. Similar results were found when we analyzed gene expression in this DTU, with the greatest number of differentially expressed genes being observed at 28 °C, which could indicate a dysregulation of different signaling pathways under this temperature. Chromosome analysis indicated that chromosome 1 harbored the highest number of changes for both DTUs for all thermal treatments. Finally, gene ontology (GO) analyses showed a decrease in the coding RNAs involved in the regulation of processes related to the metabolism of lipids and carbohydrates, the evasion of oxidative stress, and proteolysis and phosphorylation processes, and a decrease in RNAs coding to ribosomal proteins in TcI and TcII, along with an increase in the expression of surface metalloprotease GP63 in TcII. CONCLUSIONS: Slight temperature shifts lead to increased cell death of metacyclic trypomastigotes because of the deregulation of gene expression of different processes essential for the TcI and TcII DTUs of T. cruzi.

Transcriptomic changes across the life cycle of Trypanosoma cruzi II.

Trypanosoma cruzi is a flagellated protozoan that causes Chagas disease; it presents a complex life cycle comprising four morphological stages: epimastigote (EP), metacyclic trypomastigote (MT), cell-derived trypomastigote (CDT) and amastigote (AM). Previous transcriptomic studies on three stages (EPs, CDTs and AMs) have demonstrated differences in gene expressions among them; however, to the best of our knowledge, no studies have reported on gene expressions in MTs. Therefore, the present study compared differentially expressed genes (DEGs), and signaling pathway reconstruction in EPs, MTs, AMs and CDTs. The results revealed differences in gene expressions in the stages evaluated; these differences were greater between MTs and AMs-PTs. The signaling pathway that presented the highest number of DEGs in all the stages was associated with ribosomes protein profiles, whereas the other related pathways activated were processes related to energy metabolism from glucose, amino acid metabolism, or RNA regulation. However, the role of autophagy in the entire life cycle of T. cruzi and the presence of processes such as meiosis and homologous recombination in MTs (where the expressions of SPO11 and Rad51 plays a role) are crucial. These findings represent an important step towards the full understanding of the molecular basis during the life cycle of T. cruzi.

The effect of temperature increase on the development of Rhodnius prolixus and the course of Trypanosoma cruzi metacyclogenesis.

The increase in the global land temperature, expected under predictions of climate change, can directly affect the transmission of some infectious diseases, including Chagas disease, an anthropozoonosis caused by Trypanosoma cruzi and transmitted by arthropod vectors of the subfamily Triatominae. This work seeks to study the effects of temperature on the development of the life cycle, fertility and fecundity of the insect vector Rhodnius prolixus and on the metacyclogenesis of T. cruzi. All of the variables were subjected to 3 temperatures: 26°C, 28°C and 30°C. Hatching time was evaluated, along with time to fifth instar, time to adult, fecundity studied using the e-value, and egg viability during the first 3 reproductive cycles. In addition, the amounts of metacyclic trypomastigotes of the TcI and TcII DTUs in R. prolixus were evaluated from days 2 to 20 at two-day intervals and from weeks 6 to 8 post-infection. Decreases were observed in time to hatching (15-10 days on average) and in time to fifth instar (70-60 days on average) and transition to adult (100-85 days on average). No significant differences in egg viability were observed in any of the reproductive cycles evaluated, but an increase in fecundity was observed at 30°C during the third reproductive cycle. At 30°C, there was also an increase in the number of infective forms and a decrease in the time at which metacyclic trypomastigotes were detected in the rectal ampulla of the insects for both TcI and TcII. According to these results, the expected temperature increase under climate change would cause an increase in the number of insects and a greater probability of infection of the parasite, which affects the transmission of Chagas disease.

New native South American Y chromosome lineages.

Many single-nucleotide polymorphisms (SNPs) in the non-recombining region of the human Y chromosome have been described in the last decade. High-coverage sequencing has helped to characterize new SNPs, which has in turn increased the level of detail in paternal phylogenies. However, these paternal lineages still provide insufficient information on population history and demography, especially for Native Americans. The present study aimed to identify informative paternal sublineages derived from the main founder lineage of the Americas-haplogroup Q-L54-in a sample of 1841 native South Americans. For this purpose, we used a Y-chromosomal genotyping multiplex platform and conventional genotyping methods to validate 34 new SNPs that were identified in the present study by sequencing, together with many Y-SNPs previously described in the literature. We updated the haplogroup Q phylogeny and identified two new Q-M3 and three new Q-L54*(xM3) sublineages defined by five informative SNPs, designated SA04, SA05, SA02, SA03 and SA29. Within the Q-M3, sublineage Q-SA04 was mostly found in individuals from ethnic groups belonging to the Tukanoan linguistic family in the northwest Amazon, whereas sublineage Q-SA05 was found in Peruvian and Bolivian Amazon ethnic groups. Within Q-L54*, the derived sublineages Q-SA03 and Q-SA02 were exclusively found among Coyaima individuals (Cariban linguistic family) from Colombia, while Q-SA29 was found only in Maxacali individuals (Jean linguistic family) from southeast Brazil. Furthermore, we validated the usefulness of several published SNPs among indigenous South Americans. This new Y chromosome haplogroup Q phylogeny offers an informative paternal genealogy to investigate the pre-Columbian history of South America.Journal of Human Genetics advance online publication, 31 March 2016; doi:10.1038/jhg.2016.26.

Prevalence, Genetic Characterization, and 18S Small Subunit Ribosomal RNA Diversity of Trypanosoma rangeli in Triatomine and Mammal Hosts in Endemic Areas for Chagas Disease in Ecuador.

Trypanosoma rangeli is a nonpathogenic parasite for humans; however, its medical importance relies in its similarity and overlapping distribution with Trypanosoma cruzi, causal agent of Chagas disease in the Americas. The genetic diversity of T. rangeli and its association with host species (triatomines and mammals) has been identified along Central and the South America; however, it has not included data of isolates from Ecuador. This study reports infection with T. rangeli in 18 genera of mammal hosts and five species of triatomines in three environments (domestic, peridomestic, and sylvatic). Higher infection rates were found in the sylvatic environment, in close association with Rhodnius ecuadoriensis. The results of this study extend the range of hosts infected with this parasite and the geographic range of the T. rangeli genotype KP1(-)/lineage C in South America. It was not possible to detect variation on T. rangeli from the central coastal region and southern Ecuador with the analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, even though these areas are ecologically different and a phenotypic subdivision of R. ecuadoriensis has been found. R. ecuadoriensis is considered one of the most important vectors for Chagas disease transmission in Ecuador due to its wide distribution and adaptability to diverse environments. An extensive knowledge of the trypanosomes circulating in this species of triatomine, and associated mammal hosts, is important for delineating transmission dynamics and preventive measures in the endemic areas of Ecuador and Northern Peru.

Consumo de drogas emergentes en Medellín, Colombia / Use of Emerging Drugs in Medellín, Colombia

Resumen Introducción: La continua aparición de nuevas sustancias sintéticas que se puede utilizar como drogas de abuso supone un desafío constante para la salud pública. Drogas emergentes es el término acuñado en este trabajo para definir la aparición de nuevas sustancias psicoactivas en un momento dado y un contexto y un grupo particulares, la reaparición de otras que en los estudios epidemiológicos habían perdido su prevalencia y el aumento repentino en las prevalencias de drogas que se mantenían en consumos bajos. Método: Bajo un enfoque empírico-analítico, se planteó un estudio con un enfoque mixto. Conformaron la muestra de conveniencia 510 drogodependientes que en 2011 asistieron a centros de tratamiento, en la modalidad de internamiento, en el municipio de Medellín, en quienes se exploró el consumo de drogas emergentes. A todos los usuarios de drogas se les aplicó un instrumento ad-hoc para detectar consumo de las que el estudio consideraba drogas emergentes. Detectados los consumidores y seleccionados por la frecuencia del consumo y la prevalencia en el último año y el último mes, se les solicitó una entrevista semiestructurada, que indagaba por detalles de la sustancia y las características del consumo. Resultados: Del grupo estudiado en el caso de Medellín, el 82,2% son varones y el 17,8%, mujeres. El 58,2% cursa secundaria y el 26,8% tiene estudios superiores técnicos o de universidad. El 1,4% no ha ido a la escuela. Solo un 27,8% trabaja con un empleo fijo, ocasional o independiente. El 40,7% son estudiantes y el 8,9%, amas de casa. El 76,3% son solteros y el 17,8% tiene pareja estable. En la muestra están representados todos los estratos socioeconómicos. Entre las drogas emergentes halladas, se destacan las prevalencias de las benzodiacepinas flunitrazepam y clonazepam: prevalencia de vida (PV), 97,5%; prevalencia en el último año (PA), 67,9%, y prevalencia en el último mes (PM), 46,7%. Les siguen las drogas de síntesis (LSD, «éxtasis¼, anfetaminas, HGB, «éxtasis vegetal¼, fenciclidina, metanfetamina, ketamina, 2CB): PV, 96,5%; PA, 44,5%, y PM, 23,5%. Luego aparecen las cocaínas fumables (basuco, crack y free-base): PV, 80%; PA, 52,1%, y PM, 31,7%. Siguen los derivados opiáceos (heroína, morfina, opio, codeína, dextrometorfano, meperidina, fentanilo): PV, 61,4%; PA, 26,7%, y PM, 16%. Los alucinógenos como los hongos, el cacao sabanero y el yagué también aparecen entre los consumos: PV, 73,5%; PA, 23,2%, y PM, 12,2%. Hay también consumo de inhalantes como el popper y el diclorometano («Dick¼): PV, 87,9%; PA, 37,6%, y PM, 21,6%. Conclusiones: Estos resultados alertan sobre la necesidad de hacer seguimiento a las denominadas drogas emergentes por los riesgos que pueden implicar para la salud pública.

Abstract Introduction: The ongoing emergence of new synthetic substances that are used as drugs is a constant challenge to public health. Emerging drugs is the concept used in this research project to define the emergence of new psychoactive substances at a given time, a specific context and group, the reemergence of others that some epidemiologists considered had lost their prevalence, and the sudden prevalence of drugs that had low levels of consumption. Method: This research project was carried out using an empirical-analytical approach using a mixed methods study. The convenience sample was made up of 510 drug dependents institutionalized in treatment centers in Medellin in the year 2011. The examination was carried out related to the consumption of emerging drugs. An ad hoc tool was applied to all the drug users in order to identify which of the drugs of this study they considered to be emergent. Once the consumers were identified and selected based on the frequency of consumption, and the prevalence in the last year and last month, a semi-structured interview was carried out to find out details on the substances and their consumption characteristics. Results: Based on the new drug consumers in Medellin, 82.2% were male and 17.8% female. As regards education levels, 58.2% were in high school, 26.8% hold higher technical or college degrees, and 1.4% had no schooling. Only 27.8% held a steady job, occasional employment, or were independent business owners, 40.7% were students and 8.9% were housewives. More than three-quarters (76.3%) were single, and 17.8% had a steady partner. The sample represented all social classes. Of all the emerging drugs found in this study, the prevalence of benzodiazepines stands out (flunitrazepam and clonazepam), life prevalence (LP), 97.5%; last year prevalence (LYP), 67.9%, and last month prevalence (LMP), 46.7%. These were followed by the synthetic drugs (LSD, Ecstasies, amphetamines, GHB, Vegetable Ecstasies, Phencyclidine; Methamphetamine, Ketamine, 2CB), with LP, 96.5%; LYP, 44.5%, and LMP, 23.5%. Then there was smokable cocaine (Crack and Free-Base), with LP, 80%, LYP, 52.1%, and LYP=31.7%. The opiate derivatives (heroine, morphine, opium, codeine, dextromethorphan, meperidine, fentanyl) had an LP, 61.4%; LYP, 26.7% and LMP, 16%. The consumption statistics of the hallucinogens such as mushrooms, scopolamine and "yague", had an LP, 73.5%; LYP, 23.2% and LMP, 12.2%. Finally, use of inhalants such as popper and dichloromethane (Dick) had an LP, 87.9%; LYP, 37.6% and LMP, 21.6%. Conclusion: These results are an alert to the need to track the development of these so called emergent drugs due to the risks they pose for public health.

[Use of Emerging Drugs in Medellín, Colombia]. / Consumo de drogas emergentes en Medellín, Colombia.

INTRODUCTION: The ongoing emergence of new synthetic substances that are used as drugs is a constant challenge to public health. Emerging drugs is the concept used in this research project to define the emergence of new psychoactive substances at a given time, a specific context and group, the reemergence of others that some epidemiologists considered had lost their prevalence, and the sudden prevalence of drugs that had low levels of consumption. METHOD: This research project was carried out using an empirical-analytical approach using a mixed methods study. The convenience sample was made up of 510 drug dependents institutionalized in treatment centers in Medellin in the year 2011. The examination was carried out related to the consumption of emerging drugs. An ad hoc tool was applied to all the drug users in order to identify which of the drugs of this study they considered to be emergent. Once the consumers were identified and selected based on the frequency of consumption, and the prevalence in the last year and last month, a semi-structured interview was carried out to find out details on the substances and their consumption characteristics. RESULTS: Based on the new drug consumers in Medellin, 82.2% were male and 17.8% female. As regards education levels, 58.2% were in high school, 26.8% hold higher technical or college degrees, and 1.4% had no schooling. Only 27.8% held a steady job, occasional employment, or were independent business owners, 40.7% were students and 8.9% were housewives. More than three-quarters (76.3%) were single, and 17.8% had a steady partner. The sample represented all social classes. Of all the emerging drugs found in this study, the prevalence of benzodiazepines stands out (flunitrazepam and clonazepam), life prevalence (LP), 97.5%; last year prevalence (LYP), 67.9%, and last month prevalence (LMP), 46.7%. These were followed by the synthetic drugs (LSD, Ecstasies, amphetamines, GHB, Vegetable Ecstasies, Phencyclidine; Methamphetamine, Ketamine, 2CB), with LP, 96.5%; LYP, 44.5%, and LMP, 23.5%. Then there was smokable cocaine (Crack and Free-Base), with LP, 80%, LYP, 52.1%, and LYP=31.7%. The opiate derivatives (heroine, morphine, opium, codeine, dextromethorphan, meperidine, fentanyl) had an LP, 61.4%; LYP, 26.7% and LMP, 16%. The consumption statistics of the hallucinogens such as mushrooms, scopolamine and "yague", had an LP, 73.5%; LYP, 23.2% and LMP, 12.2%. Finally, use of inhalants such as popper and dichloromethane (Dick) had an LP, 87.9%; LYP, 37.6% and LMP, 21.6%. CONCLUSION: These results are an alert to the need to track the development of these so called emergent drugs due to the risks they pose for public health.

Transcriptomic analyses of the avirulent protozoan parasite Trypanosoma rangeli.

Two species of the genus Trypanosoma infective to humans have been extensively studied at a cell and molecular level, but study of the third, Trypanosoma rangeli, remains in relative infancy. T. rangeli is non-pathogenic, but is frequently mistaken for the related Chagas disease agent Trypanosoma cruzi with which it shares vectors, hosts, significant antigenicity and a sympatric distribution over a wide geographical area. In this study, we present the T. rangeli gene expression profile as determined by the generation of ESTs (Expressed Sequence Tags) and ORESTES (Open Reading Frame ESTs). A total of 4208 unique high quality sequences were analyzed, composed from epimastigote and trypomastigote forms of SC-58 and Choachí strains, representing the two major phylogenetic lineages of this species. Comparative analyses with T. cruzi and other parasitic kinetoplastid species allowed the assignment of putative biological functions to most of the sequences generated and the establishment of an annotated T. rangeli gene expression database. Even though T. rangeli is apathogenic to mammals, genes associated with virulence in other pathogenic kinetoplastids were found. Transposable elements and genes associated mitochondrial gene expression, specifically RNA editing components, are also described for the first time. Our studies confirm the close phylogenetic relationship between T. cruzi and T. rangeli and enable us to make an estimate for the size of the T. rangeli genome repertoire ( approximately 8500 genes).

Molecular characterization and diagnosis of trypanosoma cruzi and T. rangeli.

The parasitic protozoan Trypanosoma cruzi infects an estimated 16 million individuals in Latin America. In a variable proportion of patients, this infection can result in a life-threatening cardiac or digestive pathology recognized as Chagas disease. In the majority of cases, the parasitemic phase of infection is transient and often goes unnoticed against the high background of endemic diseases present in the low-income groups usually affected by T. cruzi infection. Consequently, diagnosis of the infection by direct microscopic examination is rarely possible; therefore, routine serologic procedures as well as modern molecular techniques provide the most sensitive indicators of human infection.

kDNA markers define two major Trypanosoma rangeli lineages in Latin-America.

Trypanosoma rangeli is a hemoflagellate parasite of man, domestic and wild animals in Central and South America. The genus Rhodnius is particularly susceptible to infection by T. rangeli and transmission by salivary inoculation has been demonstrated in 12 of 14 nominal species of naturally and experimentally infected insects. This report describes the molecular characterization of 37 strains of T. rangeli isolated from vertebrate and invertebrate hosts. Strains were analyzed by hybridization with kinetoplast DNA (kDNA) probes, polymerase chain reaction (PCR) amplification of kDNA minicircles and random amplification polymorphic DNA (RAPD). Strains isolated from Rhodnius prolixus present KP1, KP2 and KP3 minicircle amplification products but strains isolated from R. colombiensis or Panstrongylus megistus present amplification products derived only from KP2 and KP3 minicircles. The two T. rangeli groups defined as KP1(+) and KP1(-) present a high genetic divergence as they have probably been co-evolutioned with different adaptive radiated lines of the genus Rhodnius in Latin-America. The data obtained from insects with intestinal and salivary glands infections confirm that each Rhodnius species select the sub-population of T. rangeli KP1(+) or KP1(-) which is susceptible to transmit it by salivary inoculation to the vertebrate host.

Differentiation and genetic analysis of Rhodnius prolixus and Rhodnius colombiensis by rDNA and RAPD amplification

Domiciliated Rhodnius prolixus and sylvatic R. colombiensis were analyzed in order to confirm their genetic divergence and verify the risk that the latter represents in the domiciliation process, and to provide tools for identifying the sources of possible reinfestation by triatomines in human dwellings allowing control programs to be undertaken. Comparison of random amplified polymorphic DNA amplification patterns and cluster analysis suggests reproductive discontinuity between the two species. The calculated statistical F value of 0.24 and effective migration rate of 0.6 individuals per generation are insufficient to maintain genetic homogeneity between them and confirm the absence of present genetic flow. R. colombiensis presents higher intrapopulation variability. Polymerase chain reaction of ribosomal DNA supports these findings. The low genetic flow between the two species implies that R. colombiensis do not represent an epidemiological risk for the domiciliary transmission of Trypanosoma cruzi in the Tolima Department. The lower variability of the domiciliated R. prolixus could result in greater susceptibility to the use of pesticides in control programs

Chagas disease and human migration

Human Chagas disease is a purely accidental occurrence. As humans came into contact with the natural foci of infection might then have become infected as a single addition to the already extensive host range of Trypanosoma cruzi that includes other primates. Thus began a process of adaptation and domiciliation to human habitations through which the vectors had direct access to abundant food as well as protection from climatic changes and predators. Our work deals with the extraction and specific amplification by polymerase chain reaction of T. cruzi DNA obtained from mummified human tissues and the positive diagnosis of Chagas disease in a series of 4,000-year-old Pre-Hispanic human mummies from the northern coast of Chile. The area has been inhabited at least for 7,000 years, first by hunters, fishers and gatherers, and then gradually by more permanent settlements. The studied specimens belonged to the Chinchorro culture, a people inhabiting the area now occupied by the modern city of Arica. These were essentially fishers with a complex religious ideology, which accounts for the preservation of their dead in the way of mummified bodies, further enhanced by the extremely dry conditions of the desert. Chinchorro mummies are, perhaps, the oldest preserved bodies known to date.