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Introduction: Choriocarcinoma is a malignant tumor, it is more frequent in the female sex, rarely reported in the male sex., Clinical Case: A 19-year-old male patient who was admitted with hematochezia and melenic evacuations, panendoscopy and colonoscopy were performed without documenting the bleeding site, exploratory laparotomy was performed finding tumor lesion in the jejunum, the histopathological examination reported Choriocarcinoma., Conclusions: Gastrointestinal bleeding as a presentation of choriocarcinoma is sometimes the only symptom that the patient presents. Metastatic choriocarcinoma to the gastrointestinal tract is rare, which makes the suspected diagnosis poor., (Copyright: © 2021 Permanyer.)

Background: Post-ERCP pancreatitis (PEP) is the most common complication of Post-endoscopic retrograde cholangiopancreatography., Objective: to demonstrate whether serum amylase and lipase values correlate with the presence and severity of PEP., Method: We conducted a retrospective, observational and analytical study of patients who underwent ERCP, those who developed pancreatitis were classified by severity according to the 2012 revised Atlanta criteria and their serum enzyme levels were analyzed. We used ROC (Receiver Operating Characteristics) curves to know the best enzyme cutoff points and analyzed their diagnostic yields. Chi-square, t-distribution and Mann-Whitney U test were used in the variable analysis and it was considered statistically significant when p < 0.05., Results: A total 621 patients, 54 presented pancreatitis. For moderately severe and severe forms: lipase level of 1500 U/L had an area under the curve (AUC) = 0.827, 95% CI (0.67-0.98), sensitivity = 72.7%, specificity = 86%, negative predictive value = 92.5%, p < 0.05. Amylase level of 920 U/L presented AUC = 0.65, 95% CI (0.43-0.86), sensitivity = 63%, specificity = 67%, p > 0.05., Conclusions: Serum lipase shows correlation with the presence and severity of PEP. Amylase shows no significant correlation with PEP., (Copyright: © 2020 Permanyer.)

Background: WHO's 2020 milestones for Chagas disease include having all endemic Latin American countries certified with no intradomiciliary Trypanosoma cruzi transmission, and infected patients under care. Evaluating the variation in historical exposure to infection is crucial for assessing progress and for understanding the priorities to achieve these milestones., Methods: Focusing on Colombia, all the available age-structured serological surveys (undertaken between 1995 and 2014) were searched and compiled. A total of 109 serosurveys were found, comprising 83 742 individuals from rural (indigenous and non-indigenous) and urban settings in 14 (out of 32) administrative units (departments). Estimates of the force-of-infection (FoI) were obtained by fitting and comparing three catalytic models using Bayesian methods to reconstruct temporal and spatial patterns over the course of three decades (between 1984 and 2014)., Results: Significant downward changes in the FoI were identified over the course of the three decades, and in some specific locations the predicted current seroprevalence in children aged 0-5 years is <1%. However, pronounced heterogeneity exists within departments, especially between indigenous, rural and urban settings, with the former exhibiting the highest FoI (up to 66 new infections/1000 people susceptible/year). The FoI in most of the indigenous settings remain unchanged during the three decades investigated. Current prevalence in adults in these 15 departments varies between 10% and 90% depending on the dynamics of historical exposure., Conclusions: Assessing progress towards the control of Chagas disease requires quantifying the impact of historical exposure on current age-specific prevalence at subnational level. In Colombia, despite the evident progress, there is a marked heterogeneity indicating that in some areas the vector control interventions have not been effective, hindering the possibility of achieving interruption by 2020. A substantial burden of chronic cases remains even in locations where serological criteria for transmission interruption may have been achieved, therefore still demanding diagnosis and treatment interventions., Competing Interests: Competing interests: None declared.

Introduction: Domestic and wild triatomines in the department of Santander have an epidemiological impact, as recently they have been linked to outbreaks of acute Chagas disease. The analysis of their diversity and temporal variation contributes to the understanding of their biology and ecology in one of the most endemic areas of the country., Objectives: To analyze triatominae diversity in two regions of Santander., Materials and Methods: We analyzed the triatomine records for Santander contained in the CINTROP-UIS entomology lab database. We grouped the information for two regions: the Middle Magdalena area and the Andean region, and for each one we designed species accumulation and range-abundance curves, we calculated diversity and equality indices, and we analyzed colonization and temporal variation or persistence of the community., Results: Ninety five percent of triatomines came from the Andean area and 4.57% from Magdalena Medio, with nine and ten species each. The dominant species in the Andean area were Rhodnius prolixus and Triatoma dimidiata while in Magdalena Medio they were Rhodnius pallescens and Panstrongylus geniculatus. We found a greater diversity and richness in Middle Magdalena compared to the Andean area. The temporal variation showed persistence of communities over time., Conclusions: Results revealed differences in the diversity of the two regions and the potential of wild species to occupy artificial ecotopes. Triatomines intrusion and the recent involvement of wild species in the transmission of Trypanosoma cruzi emphasize the need to further investigate the ecology of these vectors in order to guide population control strategies.

Introduction: Notice of triatomines in dwellings of some neighborhoods in Bucaramanga motivated the realization of this study.Objetive: To evaluate the intrusion of triatomines and mammals, as well as some risk factors in urban dwellings., Materials and Methods: Triatomines were collected in a neighborhood in Bucaramanga, Santander, on a monthly basis during one year with participation of the community. Collection included manual search in lamp posts, use of light traps, animal bait, and chemical attractants in nearby forests. Reservoirs were collected with bait traps. Insects and mammals were identified and examined in order to determine their natural infection. Risk factors in homes were assessed by means of a social-environmental survey., Results: Eleven adult specimens of Pastrongylus geniculatus, as well as 63 of Rhodnius pallescens were collected in the forest, recreational peridomiciliary areas, and houses. Even two females and 21 nymphs of R. pallescens were found in bedrooms. Two specimens of Didelphis marsupialis were captured in neighboring forests. Out of the eleven P. geniculatus captured, nine were examined. Of these, five were positive for Trypanosoma cruzi. It was not possible to establish a significant risk factor;however, the dwellings with report of triatomines were located nearer to the adjacent forest., Conclusions: The finding of intrusive triatominae species and mammals with T. cruzi in intradomiciliary and peridomiciliary areas and periurban forests prove the potential risk to acquire infection from these populations that dwell in urban housing adjacent to these ecotopes where the sylvan cycle is kept.

Triatoma dimidiata Latreille is the second most important vector of Chagas' disease in Colombia and is found in urban and periurban areas. From January 2007 to June 2008, we performed field work in 8 departments, 18 municipalities, and 44 rural villages, covering most of its known distribution and all of its ecological zones in the country. The goal was to determine the geographical distribution, the ecology, and house infestation indices of T. dimidiata over its range and hence the Chagas' disease transmission risk. In Colombia, T. dimidiata occupies a wide variety of ecosystems, from transformed ecosystems in the Andean biome with shrub and xerofitic vegetation to very dense forests in the humid tropical forests in the Sierra Nevada of Santa Marta. According to genetic and ecological criteria, at least two T. dimidiata forms of this species are present: populations from the northwest of the country (Caribbean plains) are restricted to palm tree habitats, and domestic involvement is limited to sporadic visits because of attraction by light; and populations of the east region (Andean mountains) presenting a complex distributional pattern including sylvatic, peridomestic, and domiciliated ecotopes, and occupying a great variety of life zones. The latter population is of epidemiological importance due to the demonstrated migration and genetical flow of individuals among the different habitats. Control, therefore, must take into account its diversity of habitats., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Palms are ubiquitous across Neotropical landscapes, from pristine forests or savannahs to large cities. Although palms provide useful ecosystem services, they also offer suitable habitat for triatomines and for Trypanosoma cruzi mammalian hosts. Wild triatomines often invade houses by flying from nearby palms, potentially leading to new cases of human Chagas disease. Understanding and predicting triatomine-palm associations and palm infestation probabilities is important for enhancing Chagas disease prevention in areas where palm-associated vectors transmit T. cruzi. We present a comprehensive overview of palm infestation by triatomines in the Americas, combining a thorough reanalysis of our published and unpublished records with an in-depth review of the literature. We use site-occupancy modeling (SOM) to examine infestation in 3590 palms sampled with non-destructive methods, and standard statistics to describe and compare infestation in 2940 palms sampled by felling-and-dissection. Thirty-eight palm species (18 genera) have been reported to be infested by ∼39 triatomine species (10 genera) from the USA to Argentina. Overall infestation varied from 49.1-55.3% (SOM) to 62.6-66.1% (dissection), with important heterogeneities among sub-regions and particularly among palm species. Large palms with complex crowns (e.g., Attalea butyracea, Acrocomia aculeata) and some medium-crowned palms (e.g., Copernicia, Butia) are often infested; in slender, small-crowned palms (e.g., Euterpe) triatomines associate with vertebrate nests. Palm infestation tends to be higher in rural settings, but urban palms can also be infested. Most Rhodnius species are probably true palm specialists, whereas Psammolestes, Eratyrus, Cavernicola, Panstrongylus, Triatoma, Alberprosenia, and some Bolboderini seem to use palms opportunistically. Palms provide extensive habitat for enzootic T. cruzi cycles and a critical link between wild cycles and transmission to humans. Unless effective means to reduce contact between people and palm-living triatomines are devised, palms will contribute to maintaining long-term and widespread, albeit possibly low-intensity, transmission of human Chagas disease., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: The incidence of diverticular disease of the colon has been rising in recent years, and the associated factors are: low ingestion of fibre, age, lack of physical activity, and obesity., Methods: A retrospective, descriptive, observational study was conducted on patients with the diagnosis of complicated diverticular disease requiring surgical or interventional treatment, for a period of 12 years., Results: A total of 114 patients (72 males, and 42 females), age range 28-91 years. More than three-quarters (88 patients; 77.19%) had a body mass index (BMI) between 25 and 40 kg/m(2), and 26 patients (22.8%) had a BMI between 20 and 25 kg/m(2). Among the patients with BMI less than 25 kg/m(2), 12 patients had Hinchey 1 (46%), 8 Hinchey 2 (30.7%), 4 Hinchey 3 (15.4%), and two Hinchey 4 (7.7%). Of the patients with BMI greater than 25 kg/m(2), 19 patients had Hinchey 1 (21.6%), 24 Hinchey 2 (27.3%), 27 Hinchey 3 (30.7%), and 18 Hinchey 4 (20.45%). A statistically significant difference (P<0.001) was found between groups using Mann-Whitney U test. The BMI greater than 25 kg/m(2) as risk factor for complicated diverticular disease showed Odds Ratio of 3.4884 (95% confidence interval 1.27-9.55) with Z value of 2.44 (P=0.014)., Conclusions: In this study, obesity was associated with an increased incidence and severity of complicated diverticular disease., (Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.)

Introduction: Studying triatominae in their natural ecotopes has great significance in the epidemiology of Chagas disease. Gathering live insects and the establishment of insectaries allows countless studies. Therefore, effective methods are needed for capturing wild triatomines, especially intrusive species such as Rhodnius prolixus ., Objective: To compare four methods of capturing triatomines in palms to measure their effectiveness., Materials and Methods: Our study was conducted in Maní, department of Casanare, Colombia, with a predominance of A. butyracea . We compared four methodologies in 67 palms: live-bait traps, direct search in the palms, felling and dissection., Results: The methods were effective to collect juveniles and adults. Felling and manual search showed the highest infestation rates (100% and 83.33%). Higher indexes of overcrowding (4.93), density (3.76), abundance range (1-13) and adult/nymph index (0.22) were obtained with the Angulo trap. Felling and dissection was the method which significantly collected a greater number of triatomines compared with the other methods (p <0.002); it was followed by the Angulo trap. We did not find any differences in the collection of the nymphal stages among the evaluated methods (p> 0.05)., Conclusions: Even though felling was the best method for collecting the highest number of triatomines, live-bait with adhesives or shelters to trap insects were a good alternative to collect the insects in palms. Among them, the Angulo trap showed better results and it prevents the risk of exposure of the researcher and the intervention of natural ecotopes.

Introduction: The presence of Rhodnius prolixus in palms on the eastern plains area of Colombia provide a high risk for infection with Trypanosoma cruzi. Intensive surveillance of the palm tree habitat are necessary to confirm the presence of bugs and provide evidence that this habitat is a source of house infestations., Objective: The infestation by R. prolixus in the palm, Attalea butyracea, was investigated near homes for assessment of risk., Materials and Methods: Palms were examined for Rhodnius bugs adjacent to rural housing in the eastern plains provinces of Casanare and Arauca, Colombia. Bait traps were used as well as an active search by the investigators and a community watch program to collect intradomiciliary triatomine bugs. Collected species were identified by morphological criteria,and natural T.cruzi infections in the triatomine bugs were detected by the PCR technique., Results: In 111 of 172 (64.5%) palms (A. butyracea) inspected, 529 nymphs and adults of R. prolixus and 5 nymphs of Eratyrus mucronatus were collected. The A. butyracea were located within 500 m of housing. In the same period, 132 R. prolixus and specimens of the triatomine species Psammolestes arthuri,Cavernicola pilosa, Triatoma maculata, Panstrongylus geniculatus were collected inside houses. Twenty nymphs of E. mucronatus were found in a pile of bricks on the porch of a home. Natural infection of T. cruzi was detected in 28.8% of R. prolixus from palm trees and 30.0% inside houses., Conclusions: A new epidemiological scenario of transmission of Chagas disease was revealed, characterized by high rates of infestation of R. prolixus in palms near houses with frequent intrusion into houses. In designing measures to prevent Chagas disease, the association of palm trees, triatomine bugs and housing proximity is a significant consideration.

The cave organ is a sensory receptor in the antenna pedicel of some Reduviidae. This paper describes this organ for the first time in three species of the genus Belminus, Belminus corredori, Belminus ferroae and Belminus herreri, by optical and scanning electron microscopy. The structures presented a general pattern similar to one reported for other species of Triatominae.

Introduction: Wild triatomines have become increasingly important in the transmission of Chagas disease because of their frequent house entry behavior. Knowledge of their biology is limited, and few tools are available for their collection. These needs led to the design of a new trap for live triatomines., Objectives: The characteristics are described of a new bait trap designed for collecting triatomines. Trap usage and preliminary results are described for collections in several regional natural habitats in Colombia., Materials and Methods: The trap houses a live animal as bait and provides a shelter for triatomines that are attracted by the bait., Results: The trap was very effective for collecting Rhodnius prolixus, Triatoma dimidiata and Rhodnius pallescens in the natural habitats of each species. Triatomine density ranged widely in palm environments in each of two regions, and a relatively higher density in areas surrounding dwellings in the Andean region., Conclusions: The new trap for collecting triatomines proved successful in collecting live wild triatomines, using live bait native to the study areas. It is easy to transport and place, it is functions well in a variety of habitats, and it is more effective than other traps using live bait.

Introduction: Despite the importance of Triatoma dimidiata as a vector of Chagas disease, little is known of its life cycle and the efficient production of these insects for biological tests., Objective: Life cycle characteristics in the laboratory were described and optimum nutritional conditions were established for the efficient production of nymphs V stage for biological tests., Materials and Methods: We determined the time of development of the nymphal stage under controlled laboratory conditions until reaching the adult stage. In a massive rearing of stage V nymphs, fed and weighted after varying periods of fasting, distributed in weight ranges to obtain the largest proportion of individuals., Results: The time mean from egg to adult was 269 days, with a wide range of duration (174 to 598 days) and the times required for 1st, 2nd, 3rd, 4th and 5th stage development was 33, 37, 41, 61 and 69 days, respectively, with a mortality of 22%. The optimum treatment was 22 days of fasting, in which 76% of the nymphs reached stage V with a weight range from 201 to 300 mg., Conclusion: Triatoma dimidiata presented development time with broad range for some individuals, possibly due to the irregularity in the food availability. A homogenous weight range was attained with a regime of 22 days of fasting with an optimum production of stage V nymphs.

Objective: Standardising the ELISA technique for identifying triatomine insects' feeding behaviour., Methods: The ELISA test was standardised by preparing 12 animal anti-specie polyclonal antisera by immunising rabbits with sera from domestic and wild animals; the sera were titred and absorbed to improve specificity. The intestinal content of fifth-instar Rhodnius prolixus (previously fed on each host) was used as positive control; negative controls were obtained from triatomines without feeding. The intestinal content from 60 intradomicile R. prolixus collected in the field was processed to determine the test's effectiveness., Results: The high-reactivity ELISA technique was standardised in detecting every blood protein in the positive controls used here. Blood proteins from one or more domestic and wild hosts were detected in 70% of the intestinal content of triatomines collected in homes. Bird, human, pig and goat blood were the most frequent feeding sources; blood proteins from wild animals were identified in 9.5% of them., Conclusions: The technique was shown to be effective in detecting blood proteins from different hosts in the intestinal content of triatomines taken from the laboratory and the field. Even though domestic animals' blood was preferentially determined, the findings from wild animals' blood could indicate insect mobility probably from the wild to the domicile. This tool helps in understanding triatomines' behaviour regarding their hosts, thereby contributing to understanding Chagas' disease eco-epidemiology.

Because information about genome size in triatomines is scarce and contradictory, we performed DNA quantification by flow cytometry in 13 species belonging to five genera (Dipetalogaster, Eratyrus, Panstrongylus, Rhodnius, and Triatoma) to infer overall tendencies and phylogenetic associations. The results show that the haploid DNA content of the subfamily Triatominae varies nearly 4-fold, from<0.7 pg in Rhodnius species (0.6x10(9) bp) to 2.7 pg in Triatoma delpontei (2.6x10(9) bp). Considering that triatomines present similar chromosome numbers, we suggest that genome size differences are the result of variation in the quantity of repetitive DNA sequences localized in hetero and euchromatin. Changes in heterochromatin are particularly important when considering populations or closely related species; in more distant taxa, euchromatic changes also play a role. Our analyses indicate that flow cytometry is a useful tool for population, taxonomic, and evolutionary studies in this subfamily.

Introduction: The susceptibility to insecticides of triatomine species must be evaluated because of their involvement in the transmission of the Chagas disease. In each region with Chagas endemicity, evaluation of insecticide response is necessary to predict the success of the control campaigns., Objective: The baseline susceptibility was determined for the active principles deltamethrin, beta-cypermethrin and fenitrothion in nymphs of first and fifth instar of Triatoma dimidiata and nymphs of first instar of Triatoma maculata., Materials and Methods: The insecticide activity in triatomines was evaluated by the technique of topical application., Results: The values of the LD50 in nymphs of first instar for T. maculata, expressed in nanograms per insect (ng/i), were 0.07, 0.05 and 4.12 for deltamethrin, beta-cypermethrin and fenitrothion respectively. The corresponding LD99 values were 1.08, 0.37 and 17.89 ng/i. In T. dimidiata, the LD50 values were 0.44, 0.46 and 16.45 ng/i; the LD99 values were 2.22, 1.97 and 36.07 ng/i. In nymphs of fifth instar T. dimidiata, the LD50 values were 510.7, 1623.6 and 838.9 ng/i; the LD99 values were 9607.5, 11,717.9 and 1525.0 ng/i, respectively., Conclusion: In first instar nymphs of T. dimidiata and T. maculata, the pyrethroid insecticides were more effective; in fifth instar nymphs of T. dimidiata, the effectiveness of the pyrethroids and the organophosphate differed in the LD50 comparison--the nymphs required much higher doses compared with the other triatomines and suggested a low susceptibility. The LD99 for the organophosphate (fenitrothion) was significantly lower and may indicate its greater effectiveness in field. Studies of synergistic effects amonst insecticides are important to clarify the role of biochemical mechanisms that determine tolerance to the pyrethroids. Insecticide tolerance represents a new challenge for control campaigns in the Andean and Central American countries where Chagas disease is endemic.

Introduction: Triatoma dimidiata is one of the widely distributed triatomines in Colombia. The phenotype of the antenna is a characteristic of populations that can differ among habitats and can give information concerning its biology and behavior. This information in turn can be used in the development of new methodological proposals for its control., Objective: The behavior of populations of Triatoma dimidiate was studied in several different habitats, using the antennal phenotype., Materials and Methods: A mechanoreceptor and three chemoreceptors were compared in the antennae of 60 Triatoma dimidiata adults from several defined habitats in Santander, using unvariate and multivariate analyses., Results: The multivariate analysis differentiated the female populations significantly. These differences were associated with variations in the number of thick-walled trichoids and with the numerical increase of the thin walled trichoids in habitats close to human housing. The males, with a larger number of sensilla and thin walled trichoids, were not differentiated significantly, although, similar tendencies were observed. Sexual dimorphism was clear in these characters in the total population, but less pronounced in the domestic populations., Conclusions: The antennal sensilla patterns were useful in the intraspecific differentiation of Triatoma dimidiata in different habitats. The differences in the female population shed light on new sensorial arrangements for the exploration of the habitat, in contrast with the male populations that, because of their great capacity for dispersion, were not differentiated in the distinct habitats. The differences in sensilla patterns between females from urban areas and those from rural surroundings may be a simple and efficient marker of the origin of individual Triatominae attempting to colonize new habitats.

Introduction: Between 1998 and 2000, the occurrence of 8 cases of American visceral leishmaniasis in children from a recently established human settlement in Guatiguará, in the municipality of Piedecuesta (Santander, Colombia) indicated the possible presence of Leishmania transmission in this locality. This observation motivated the current entomological investigation., Objectives: To determine the relative frequency of Lutzomyia longipalpis inside houses and outdoors, and the natural infection of this vector with Leishmania spp., Materials and Methods: CDC light traps were used for sampling inside houses and outdoors, and sand flies were collected on human volunteers and domestic animals, and in resting places, during the period from May 1999 through September 2000. Natural infection was determined by PCR, in pools of female Lutzomyia longipalpis., Results: A total of 7,391 phlebotomine sand flies were collected. The predominant species was Lutzomyia longipalpis (Lutz & Neiva), representing 99.5% of captures. In the sand flies collected with CDC light traps, L. longipalpis was more frequently collected indoors than outdoors (p = 0.0001). The total rate of natural infection was 1.93% and a positive correlation was observed between months with higher abundance and the number of infected females entering human dwellings., Conclusions: The results indicate that in Guatiguará Lutzomyia longipalpis, shows marked tendency for the indoors, which has important implications for leishmaniasis transmission. Furthermore, transmission risk is increased during the months of higher abundance due to the entry of a higher number of infected females. From the standpoint of control, this behaviour permits the design of strategies to reduce indoor transmission.

The wide geographical distribution of Triatoma dimidiata, one of the three major vectors of Chagas disease, ranges from Mexico to northern Peru. Since this species occupies a great diversity of artificial and natural ecotopes, its eradication is extremely difficult. In order to assist control efforts, we used chromosome analyses and DNA amount as taxonomic markers to study genetic variability in populations of T. dimidiata from Mexico, Guatemala, El Salvador and Colombia. We differentiated three groups or cytotypes defined by characteristic chromosome C-banding patterns and genome size measured by flow cytometry. The three cytotypes are restricted to different geographic locations. Cytotype 1 occurs in Mexico (excluding Yucatán), Guatemala (excluding Petén), El Salvador and Colombia. Cytotype 2 occurs in Yucatán and cytotype 3 occurs in Petén. Cytotype 1, commonly associated with domestic and peridomestic environments but also inhabiting sylvatic ecotopes, is the most widespread and with major epidemiological significance. In contrast, the Yucatán cytotype inhabits wild ecotopes but increasingly enters houses, while the Petén cytotype appears exclusively sylvatic. We suggest that these cytotypes represent cryptic species of T. dimidiata with different epidemiological relevance as Chagas disease vectors. Poor ability to colonize human dwellings, together with their restricted geographic distribution, indicate that the Yucatán and Petén putative species probably have much less epidemiological significance than cytotype 1. Thus, the genetic markers we describe are powerful tools to differentiate cryptic species in T. dimidiata with different epidemiological significance, contributing to planning the most effective control measures.

Antennal sensilla patterns were used to analyze population variation of domestic Rhodnius prolixus from six departments and states representing three biogeographical regions of Colombia and Venezuela. Discriminant analysis of the patterns of mechanoreceptors and of three types of chemoreceptors on the pedicel and flagellar segments showed clear differentiation between R. prolixus populations east and west of the Andean Cordillera. The distribution of thick and thin-walled trichoids on the second flagellar segment also showed correlation with latitude, but this was not seen in the patterns of other sensilla. The results of the sensilla patterns appear to be reflecting biogeographic features or population isolation rather than characters associated with different habitats and lend support to the idea that domestic R. prolixus originated in the eastern region of the Andes.

In recent years, there has been a revitalization of large-scale programmes to control parasitic disease in developing countries. In 1997, the Governments of Colombia, Venezuela, Ecuador and Peru committed themselves to replicate the cost-effective elimination of Trypanosoma cruzi transmission achieved in the Southern Cone by using insecticides against the domestic triatomine vectors (in combination with blood-bank screening). Central American Governments launched a complementary initiative. All plan to interrupt vectorial transmission throughout the region by 2010 but specific targets are decided nationally. In this article, we highlight the novel approach taken by the Colombian Government for determining the geographic distribution of Chagas disease risk to select where to intervene first.

The performance of 4 serological tests for the diagnosis of Chagas disease was evaluated in Santander, Colombia, a region still presenting active transmission. Serum samples from 638 individuals were submitted to an enzyme immunoassay test (EIA), using total lysate of a local Trypanosoma cruzi strain and 52.5% were positive (335/638). A subset of this group (94 positive individuals and 90 seronegatives) was randomly selected for further serological confirmation. Three additional tests were used--indirect immunofluorescence (IIF) and 2 distinct enzyme-linked immunosorbent assays using total lysate of the Y strain (EIA BM) and a mixture of 2 recombinant antigens (EIA RA). Seventy-nine patients were seropositive in all tests (84.0%-79/94). The number of positive sera with the IIF, EIA RA and EIA BM was 84/94 (89.4%), 80/94 (85.1%) and 79/94 (84.0%), respectively. In 15 out of the 94 EIA seropositive patients (16.0%), 10 individuals were negative in all 3 tests (10.6%-10/94). One was negative in the EIA BM and positive in the other two tests (1.1%-1/94) and 4 patients were positive, solely, in the IIF assay (4.3%-4/94). Relative to the 90 EIA negative individuals, 89 were confirmed in all other tests (98.9%-89/90). One individual, although seronegative in the IIF, was positive in both confirmatory EIA tests (1.1%-1/90). In addition, 120 blood specimens were submitted to PCR amplification. This group consisted of 79 confirmed seropositive cases, 16 individuals with discordant serological results and 25 validated seronegative individuals. The PCR was able to detect the presence of parasite DNA in 67 out of the 79 seropositive patients (84.8%), in 8 individuals with discordant serology (50.0%) and in only one seronegative individual (4.0%). The results pointed to the necessity for performing more than one serological test, preferentially with antigens from autochthonous strains, to achieve a reliable diagnosis of Chagas disease in Colombia.

Belminus herreri, originally described from specimens collected in Panama, was considered entirely silvatic until to 2000 when it was found for the first time in a domestic habitat in Colombia. In 2001, during a new search of houses in the Department of Cesar, Colombia, 121 specimens were collected. Study of their feeding sources using an ELISA test revealed that 96% of these specimens had fed on cockroaches (Blattidae). However, a small proportion of these B. herreri specimens also showed the presence of Trypanosoma cruzi in their gut contents, suggesting a possible role for these insects in the epidemiology of Chagas disease.

The genus Panstrongylus includes 14 species widely distributed from Mexico to Argentina, some of them with great epidemiological significance as vectors of Chagas disease. We study the karyotype and the male meiotic process of Panstrongylus chinai, P. geniculatus, P. herreri, P. lignarius, P. megistus, P. rufotuberculatus and P. tupynambai. All species present the same sex mechanism (X(1)X(2)Y in males and X(1)X(1)X(2)X(2) in females) and they also have 20 autosomes, with the exception of P. megistus that only presents 18 autosomes. The analysis of C-banding patterns and meiotic chromosome behaviour show a great level of variability allowing the identification of three clearly differentiated groups. In the first group, we only include P. megistus because of its unusual number of autosomes. The second group includes P. chinai, P. herreri, P. lignarius and P. rufotuberculatus. Their autosomes present terminal heterochromatic regions that appear scattered throughout the nucleus and associated with the sex chromosomes. Actually, P. herreri and P. lignarius can be considered cytogenetically identical. Our results are in agreement with morphological, ecological and molecular data indicating that they should be regarded as the same species. The third group only includes P. tupynambai that shows autosomes without C-positive regions. Panstrongylus geniculatus shares characters will all the three groups. Its karyotypic features are extremely polymorphic depending on their geographic origin. Some populations do not show any heterochromatic regions, while others exhibit few or several heterochromatic blocks. The chromosomal variability observed, together with its wide distribution and phenetic variability, suggest that P. geniculatus is a species complex comprising at least two distinct species. Considering the entire subfamily, the level of cytogenetic variation in Panstrongylus is lower than that observed in Triatoma but considerably more than that of Rhodnius, which is a very homogenous genus in terms of chromosome appearance and behaviour. This would endorse the closer relationship between Panstrongylus and Triatoma, and their divergence from Rhodnius, in accordance with current tribal classification.

The Triatomine bug Belminus herreri, previously known only from Panama, is reported for the first time from Colombia. Three adult B. herreri were collected from a chicken coop and a viable egg was found on a Bactris palm at Carmen municipality in humid forest zone at 680 m altitude. From 44 eggs produced, five progeny were reared to adulthood. During early instars they were unable to take bloodmeals directly from vertebrate hosts, but they fed successfully by cleptohaematophagy on blood from replete Rhodnius prolixus.