Feeding behaviour of Belminus ferroae (Hemiptera: Reduviidae), a predaceous Triatominae colonizing rural houses in Norte de Santander, Colombia.

Belminus ferroae (Hemiptera: Reduviidae) was collected from houses in the localities of San Alberto and Santa Catalina in the municipality of Toledo, Department of Norte de Santander, Colombia. Precipitin tests revealed that the main hosts of B. ferroae are insects belonging to the order Blattodea, whose haemolymph serves as food (89.43%). A low rate of haematophagy was indicated on rodents, dogs and humans (7.32%) and no natural infection with Trypanosoma cruzi was found by either microscopic examination or polymerase chain reaction. The finding of B. ferroae inside houses, feeding primarily on Blattodea with only a minor tendency to feed on vertebrate blood, is indicative of both the evolutionary path from predator to blood-sucker taken by Triatominae and their tendency to adapt from silvatic to domestic habitats.

Epidemiology of American tegumentary leishmaniasis in domestic dogs in an endemic zone of western Venezuela.

Domestic dogs are not only reservoir hosts of the American zoonotic visceral leishmaniasis (ZVL) but of the American zoonotic tegumentary leishmaniasis (ATL) as well, for different reasons. However it is still controversial to state that dogs are incriminated as ATL reservoir hosts as there is evidence that humans and dogs are likely to be exposed in the same way to sandfly vector. In Venezuela this issue has not been completely addressed, for this reason we selected a location inside Trujillo city to study eco-epidemiological conditions as well as to survey a significant sample of dogs by Montenegro Skin Test (MST). Antigen was prepared according to standard procedure using Leishmania (V) braziliensis promastigotes (80 microg/ml); response was read 48 hours post-inoculation with an induration size > 5 mm being considered as positive. The study place is an endemic mountainous semi-urban area located at 850-950 masl with an average rainfall of 150 mm/year. We evaluated 61 dogs in 46 houses with 168 human beings. Among the human population 27 cases of ATL were reported (16.1%). With the MST we found 19 positive-reaction dogs (31%) (mean MST size of 9.58 mm, 95% CI: 8.41-10.75) in 13 houses (28%). Multivariate analysis did not reveal significant association between domestic MST positive-dog ownership and human ATL cases (RR = 1.48, p = 0.28). Although some studies have indicated that dog ownership and dog infection rates are associated with an increased risk of human disease in different evaluated places, this question has not been completely answered in Venezuelan studied zones, further research is necessary.

Actividad inhibitoria de cepas del género bacillus sp. contra dermatofitos / Inhibotorial activity of bacillus sp. against dermatophytes

Muestras de estiércol de animales domésticos procedentes del estado Trujillo, Venezuela, fueron procesadas para aislamiento de bacterias esporuladas pertenecientes al género Bacillus, para ensayarlas contra dermatofitos y determinar su actividad antifúngica. Un total de 52 cepas de células esporuladoras fueron aisladas, de las cuales el mayor número (19 cepas) fue de gallinas, seguido de caprinos (12 cepas). De vacunos, equinos y porcinos se aislaron 07 cepas de cada una de las muestras. De los 60 pacientes atendios en Consulta de Dermatología del Centro de Investigaciones "José Witremundo Torrealba" del Núcleo Universitario "Rafael Rangel" de la Universidad de Los Andes en Trujillo, por presentar diferentes afecciones de la piel, se aislaron 3 especies diferentes de dermatofitos: Trichofyton rubrum, Trichphyton mentagrophytes y Microsporum canis. De las 52 cepas del género Bacillus, aisladas en nuestro laboratorio el 23 por ciento (12 cepas) resultaron activas para inhibir el crecimiento en dos de las tres especies de dermatifitos: T. mentagrophytes y T. rubrum. Contra M. canis mostraron actividad inhibitoria el 21 por ciento (11) de las cepas aisladas. Destacamos que esta actividad antigúngica se produzca en medios de cultivo relativamente sencillos y económicos, lo cual sugiere el hallazgo de un campo de investigación aplicada contra un área clínica de agentes etiológicos que afectan a la epidermis

Evaluación de la termorresistencia en metabolitos antifúngicos producidos por esporulados del género bacillus / Evaluation of the thermoresistance in antifungal from sporulates genus bacillus

Doce (12) cepas de Bacillus sp., activas para inhibir el crecimiento de hongos agentes causales de dermatosis en humanos, fueron ensayadas para determinar termorresistencia de los metabolitos antifúngicos. Las cepas fueron masificadas en infusión de papa a pH 7,4, y, después de 96 horas de crecimiento en agitación, fueron esterilizadas a 121°C durante 15 minutos. Los cultivos fueron entonces ensayados contra dermatofitos (Trichofyton rubrum, Trichofyton Microsporum canis) sembrados en placas de Petri contentivas de 10 ml de agar Sabouraud. Los cultivos esterilizados fueron colocados en penicilindros sobre el agar solidificados y revisados hasta verificar la actividad inhibitoria de los esporulados sobre el crecimiento de los dermatofitos. En el 58 por ciento de las cepas (07) se verificó la termoresistencia de los metabolitos producidos por Bacillus sp. Resaltamos la importancia de los hallazgos, utilizando una metodología sencilla de aplicar en cualquier laboratorio y la utilización de medios de cultivo artesanales, que no requieren activos de difícil obtención, por lo que representa una área de obtención a ser explorada

Aislamiento e identificación de dermatofitos: agentes causales de dermatomicosis en el estado Trujillo, Venezuela / Isolation and identification of dermatophytes: agents of dermatomycosis in the Trujillo state, Venezuela

Las dermatomicosis constituyen una de las principales causas de consulta dermatológica. En nuestro laboratorio se recibieron 200 pacientes provenientes de la Consulta de Dermatología del Centro de Investigaciones "José Witremundo Torrealba" en la Universidad de Los Andes, Trujillo, Venezuela, los cuales acudieron por presentar afecciones en la piel. El mayor número ellos fue representado por mujeres (99= 49,5 por ciento) y hombres (81= 40,5 por ciento), mientras que los niños representaron el menor porcentaje (20 =10 por ciento). Se aislaron 60 cepas de hongos clasificadas en 3 especies diferentes: Trichophyton rubrum (33 cepas), trichophytum mentagrophytes (18 cepas) y microsporum canis (33 cepas), y microsporum canis (09 cepas). Nuestros resultados concuerdan con los hallazgos de otros investigadores en zonas diferentes, por lo cual se asume que estas tres especies representan los principales agentes causales de dermatofitosis

Diversity and species composition of sand flies (Diptera: Psychodidae) in a Venezuelan urban focus of cutaneous leishmaniasis.

The present study examined the spatial and temporal abundance and diversity of phlebotomine sand flies in an area of Venezuela that is an ancient focus of leishmaniasis. The study was conducted in 6 stations in urban localities in Trujillo City, located in northwestern Venezuela (9 degrees 22' 24" N, 70 degrees 26' 08" W), which is located in a mountain range in the Andean ecoregion (altitude = 600-1,010 m). During 1995-99, entomological surveys were conducted after and before the rainy season. Shannon light traps were operated from 1800 to 2000 h in peridomestic site trap locations. Twelve species were captured, and Lutzomyia youngi, L. ovallesi, L. scorzai, L. gomezi, L. lichyi, and L. shannoni occurred at all localities in each year. The abundance of these species showed low variation over time but high variation between localities. The Sørensen similarity index, used to compare diversity between years within each locality, ranged from 0.60 at Carmona to 0.84 at La Hacienda. Sand fly communities exhibited annual variation in species richness and diversity. Variations were affected more by changes in species abundance than by changes in species composition. Lutzomyia ovallesi, L. lichyi, and L. scorzai had the highest coefficient of variation between years (63, 38, and 23%, respectively).

Persistencia de la transmisión de la enfermedad de chagas sin colonización por el vector conocido, en localidades controladas de Venezuela / Persistent transmission of chagas disease in controlled Venezuelan localities in absence of known domestic vectors

Utilizando tres técnicas serológicas anti-Trypanosoma cruzi se ha estudiado la seroprevalencia para la enfermedad de chagas en ocho comunidades rurales del área endémica del estado Trujillo, Venezuela. De 647 personas investigadas, que representan el 41 por ciento de la población residente en viviendas no colonizadas por Rhodnius prolixus, 124 (19,2 por ciento) resultaron reactivas con al menos dos de las tres técnicas utilizadas. La seropositividad en niños menores de 10 años fue del 2,8 por ciento (7/244). Estos resultados revelan que actualmente persiste la transmisión de la enfermedad de chagas en regiones controladas y en viviendas no localizadas por triatominos, ello plantea la necesidad de revaluar la situación epidemiológica del estado Trujillo

Reacción intradérmica de un antígeno monovalente de Leishmania (viannia) brasilensis en casos de leishmaniasis cutánea en el estado Trujillo, Venezuela / Intradermic reaction to a monovalent anti-gen of leishmania (viannia) brasiliensis in cases of cutaneous leishmaniasis in the state of Trujillo, Venezuela

La leishmaniasis tegumentaria en el estado Trujillo es una enfermedad endémica. Actualmente existe una alta incidencia, de 120 a 130 casos nuevos/año, procedente de distintos sectores en la entidad, afectando a todos los grupos etários. Una herramienta utilizada para su diagnóstico es el test de Montenegro o "leishmania", que permite evidenciar la exposición al parásito causante de esta enfermedad, protozoo del género Leishmania, subgéner Viannia, que puede generar respuestas diferentes en el paciente ante un antígeno preparado como base de la leishmania. Nos propusimos hacer la revisión de la técnica empleada en el diagnóstico de la leishmaniasis por medio de la intradermorreacción (IDR), estandarizar la técnica.

Acute Chagas' disease in western Venezuela: a clinical, seroparasitologic, and epidemiologic study.

A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phase patients in areas of western Venezuela where Chagas' disease is endemic showed 19 symptomatic patterns or groups of symptoms appearing in combination with different frequencies. The symptomatic pattern with the highest frequency was that showing simultaneously fever, myalgia, headache, and Romaña's sign, which was detected in 20% of the acute-phase patients. Asymptomatic individuals and patients with fever as the only sign of the disease made up 15% and 11.9% of the total acute cases, respectively. Statistical correlation analysis revealed that xenodiagnosis and hemoculture were the most reliable and concordant of the five parasitologic methods used; these two methods also showed the highest proportions in detecting any clinical symptomatic pattern in acute-phase patients. A similar high reliability and concordance was obtained with a direct agglutination test, an indirect immunofluorescent antibody test, and an ELISA as serologic tests, which also showed a higher proportion of positive detection of clinical patterns than parasitologic methods (P < 0.001). It is recommended that individuals coming from endemic areas showing mild and/or severe clinical manifestations should be suspected of being in contact or having been in contact with Trypanosoma cruzi, be referred for parasitologic and serologic evaluations to confirm the presumptive clinical diagnosis of acute Chagas' disease, and start specific treatment. The epidemiologic implications of the present findings are discussed and the use of similar methodology to evaluate other areas where Chagas' disease is endemic is suggested.

[Presence of metacyclical promastigotes of Leishmania pifanoi in the hypopharynx of Lutzomyia youngi and their sugar consumption]. / Presencia de nectomonadas metacíclicas de L. pifanoi en la hipofaringe de Lutzomyia youngi y la ingestión de azúcares.

The presence of metacyclical promastigotes of Leishmania pifanoi in the hypopharyngeal duct of Lutzomyia youngi is reported. The insects were experimentally infected by engorgement on the tarsal lesions of hamsters. The metacyclics, whose morphology is illustrated, appeared in the hypopharynx 5 to 9 days after engorgement; they were more frequently found in the insects fed on unrefined commercial sugar. They role of amino derivates of glucose and galactose, as well as of amino acids in the development and migration of metacyclics, is investigated.

Extended HLA haplotypes among the Bari Amerindians of the Perija Range. Relationship to other tribes based on four-loci haplotype frequencies.

Extended HLA haplotypes among Bari Amerindians living at the Perija Range on the limits between Colombia and Venezuela have been defined using serology for class I, electrophoresis and immuno-fixation for Bf and C4, and PCR-SSO for class II loci typing. Haplotypes were assigned based on family studies and gene frequencies were calculated using a subset of less related subjects selected from the genealogy. No rare class III variants were observed, but the characteristic low HLA diversity of isolated Amerindians populations present also in the Bari extends to Bf and C4. Thus there were only 22 different haplotypes segregating in families when nine loci were considered. All of them except three carried Bf*S, C4A*3, C4B*1. The null allele C4A*Q0 reached a frequency of 0.147 and was predominantly present in A24 Cw7 B39 DRB1*0411 haplotypes. In contrast to what has been reported using HLA alleles or class I haplotype frequencies and other isolated South American tribes, genetic distance estimates based on A-Cw-B-DR haplotype frequencies show a closer relationship between the two linguistically but geographically distant Venezuelan tribes, the Bari and the Warao, as compared to two culturally different Brazilian populations. The information reported here will be useful for identifying ancestral haplotypes in native peoples of America, for population comparison, and for discussing the differential influence of MHC haplotype diversity and population survival when similar data on other Amerindian tribes becomes available.

[Excretion of promastigotes of Leishmania pifanoi by experimentally infected Lutzomyia youngi]. / Excreción de promastigotos de Leishmania pifanoi por Lutzomyia youngi experimentalmente infectada.

The increase in the promastigotes population of Leishmania pifanoi in Lutzomyia youngi experimentally infected and kept on 50% sacarose under constant conditions of temperature and humidity is described. Two stages in the differentiation and growth of the parasites are recognised between two and twenty-four hours after meals. The pleomorphic differentiation of the amastigotes in short promastigotes which multiply by binary division for 60 hours, when the rupture of the peritrophic membrane occurs, takes place within 48 hours. The second stage occurs between 72 and 96 hours when some of the parasites migrate to the esophagic valve and the rest of the free parasites are excreted in fecal drops as large, active promastigotes. The first drops excreted react positively to glucose or contain crystals of urate. The excess promastigotes of the second stage of development are eliminated in the last excretions and react positively to the Hemoscreen and Biuret tests for total proteins as also for glucose and account for 82% of the of drops excreted. The excretion of parasites by Lu. youngi is a normal stage in the growth of L. pifanoi into a vector.

[Leishmania braziliensis: isolation from lesions by inoculation of hamsters with and without addition of salivary gland lysate from Lutzomyia youngi]. / Leishmania braziliensis: aislamiento de lesiones por inoculación de hámsteres con o sin adición de lisado de glándulas salivares de Lutzomyia youngi.

Homogenized biopsy tissue from the cutaneous leishmaniasis lesions of 50 patients from Trujillo, Venezuela, were inoculated subcutaneously into the tarsi of male hamsters. Homogenized tissue either alone or mixed with salivary gland lysates of Lutzomyia youngi were used for inoculation. Homogenized tissue alone yielded 58.5% of infections with a mean of twelve weeks for prepatency, while those mixed with sandfly lysate resulted in 92% of infections with a mean prepatency of three weeks.

Physiological age in Lutzomyia youngi (Diptera: Psychodidae) populations from an endemic area for cutaneous leishmaniasis, Venezuela.

Batches of sylvatic females of Lutzomyia youngi (Phlebotominae) captured in a Shannon trap on twelve occasions over one year in a locality where subcutaneous leishmaniasis is endemic, near the city of Trujillo, Venezuela, were used to study: 1) the percentages of parous females according to previously established criteria and 2) the average number of eggs laid spontaneously by isolated females during 7 days after feeding on hamsters. The data on the batches of females captured on nights previous to the rainy period (prepluvial) were compared with those on females captured after the rains (postpluvial). Significant differences were detected by variation analysis for two variables and different number of N, as also were consistent groupings by Duncan's Test for pre- and postpluvial lots of females. The females captured on nights prior to the rainy periods (January-March and August-September) presented higher rates of nulliparity (86-72%) and contained or laid a greater number of eggs (71-67) than those captured after the rains (March-June and November-December) which presented lower rates of nulliparity (60-24%) and a smaller number of eggs (50-30). The rainfall peaks occurred in April and September-October, respectively. It is considered that these differences can be used by epidemiological studies as a means of estimating the physiological age of female populations of L. youngy.

Presence of Leishmania braziliensis in blood samples from cured patients or at different stages of immunotherapy.

By using a PCR assay specific for Leishmania braziliensis in blood samples, we detected this parasite in patients cured by immunotherapy or at different stages of treatment. We also found the parasite in subjects who had never suffered leishmaniasis but who had lived in endemic areas and migrated to nonendemic ones many years ago. These results suggest that L. braziliensis infections are difficult to eradicate and that a clinical cure but rarely a complete elimination of the parasite is generally accomplished.

Identification and detection of Trypanosoma cruzi by using a DNA amplification fingerprint obtained from the ribosomal intergenic spacer.

We designed a PCR assay targeted on repeated elements of the ribosomal intergenic spacer which produces highly polymorphic DNA band patterns for different strains of Trypanosoma cruzi. By labeling the PCR products with digoxigenin and by chemiluminescence detection, we improved the assay sensitivity by three orders of magnitude to get T. cruzi strain fingerprints in feces of the trypanosome-infected triatomine bug vector. We also developed a capture assay for the digoxigenin-labeled PCR products that allowed us to detect T. cruzi in triatomine bug vector feces and in human serum samples with a solid support.

Identification of new world Leishmania using ribosomal gene spacer probes.

DNA probes from the nontranscribed ribosomal spacer (NTS), of Leishmania garnhami and Leishmania braziliensis were constructed and tested for sensitivity and specificity against different Leishmania isolates. The L. garnhami probes were species-specific under hybridization conditions of high stringency, but displayed specificity for the mexicana complex under conditions of intermediate stringency. The L. braziliensis probes showed 'complex' specificity. RFLP for the nontranscribed spacer within the braziliensis complex revealed very homogeneous patterns even for organisms currently accepted as different species. A PCR assay for the detection of Leishmania from the braziliensis complex is presented.