Conocimiento epidemiológico y situación actual de la enfermedad de Chagas en el estado de Jalisco, México / Epidemiologic knowledge and current situation of Chagas disease in the state of Jalisco, Mexico

La enfermedad de Chagas en el estado de Jalisco, México, apareció por primera vez en 1967, aunque su conocimiento ha seguido un proceso lento. Entre los años de 1967 y 2006 se describió la enfermedad en sus formas agudas y crónicas; se identificaron las especies de vectores y se aisló el parásito Trypanosoma cruzi, que luego se caracterizó en el plano genético. La magnitud de la infección en el hombre se determinó con estudios serológicos en diversas poblaciones, así como en donadores de sangre. En la actualización presente del conocimiento de la enfermedad en el estado de Jalisco se mostró la necesidad de incrementar las investigaciones sobre la epidemiología de la enfermedad de Chagas, así como los estudios clínicos para determinar la salud de los individuos y las poblaciones.

Chagas disease in the state of Jalisco, Mexico was described for the first time in 1967; however, knowledge on the disease remains in a slow process. Between 1967 and 2006, the disease was described in its acute and chronic forms. The vector species have been identified, and the parasite Trypanosoma cruzi has been isolated and genetically characterized. Also, the magnitude of the infection in humans has been determined through serological studies of different populations as well as of blood donors. The up-to-dateness of knowledge of the disease in the state of Jalisco, unveils a necessity of increased research on the epidemiology of Chagas disease as well as on clinical studies to assess the health of individuals and the populations.

Preliminary results of random amplification of polymorphic DNA among Triatominae of the phyllosoma complex (Hemiptera, Reduviidae)

In Mexico, Triatoma longipennis (Usinger), Triatoma picturata (Usinger), and Triatoma pallidipennis (Stal), primary Chagas disease vector species of the phyllosoma complex, were analyzed by randomly amplified polymorphic DNA (RAPD). Sixteen decametric primers resolved individual profiles not identical, but partially discriminative between species. Analysis based on pairwise presence/absence comparisons between the three species was performed using three primers and two outgroup species Triatoma infestans (Klug) and Triatoma barberi (Usinger). Fifty-three bands in total were scored, although only two bands were constant among the three phyllosoma complex species. Two other bands were constant only for T. longipennis and T. picturata together, and not present in T. pallidipennis. Neighbor Joining tree and the multiple correspondence analysis discriminated T. pallidipennis clearly from the other two species, although there was overlap between T. longipennis and T. picturata. The results indicate a close relationship between the studied species and support the hypothesis of their recent evolution. The suitability of RAPD to discern populations within the species is discussed.

Detección e identificación de complejos de leishmania a traves de la reacción en cadena de la polimerasa (PCR) e hibridación con sondas especificas de complejo / Valores hematologicos en recien nacidos sanos habitantes de altura: 3600 msnm

Pregutna de investigación. ¿Los iniciadores L1 y L2 serán útiles en la detección e identificación de complejos de Leishmania, logrando una alta sensibilidad y escificidade de la Reacción en Cadena de la Polimerasa? Objetivo. Evaluar los iniciadores L1 y L2 para la identifcación de complejos de Leishmania a trvés de técnicas moleculares: Reacción en Cadena de la Polimerasa (PCR) e hibridación con osndas específicas de ADN de Kinetoplasto. Diseño. Básico experimental. Métodos.El presente estudio se realizó en 27 cepas de referencia caracterizadas previamente por electroforesis de isoenzimas. para la Reacción en Cadena de la Polimerasa se utilizo iniciadores L1 y L2, diseñados a partir de la secuenciación realizado por 1. Estos se alinean en la parte consevada y amplifican la arte variable de los minicírculos de ADN de kinetoplasto. Las sondas fuern elaboradas a partir de losproductos de PCR, seleccionado bandas mayores para tres complejos: brasiliensis (MHOM/BO90/CG); mexicana (MNYC/BZ/6"/M379); y denovani (MHOM/BR/74/PP75). La tecnica de hibridación fue realizada bajo condiciones de alta astringencia que nos da la seguridad de una alta homología entre las sondas y el ADN reconocido por ellas. Resultados. Se ha obtenido un perfil polimórfico para cada una de las cepas en estudio, con una alta selsibilidad de la técnica de PCR, amplificando varios Kinetoplastidae además de Leishmania, entre ellos Trypanisoma cruzi, Trypanisoma rangeli y Tripanisoma brucei. Las sondas presentan una alta especificidad logrando así racionalizar el amplio polimorfismo obtenido por PCR. Las sondas son una herramienta uútil para la detección e identificación directa de complejos de Leishmania. Conclusiones. Los idicadores L1 y L2 dan un perfil polimófico para cada cepa, presentando una sensibilidad muy alta, sin embargo no son específicos lde Leishmania, amplifican otros Kinetoplastidae. Este alto polimorfismo se racionaliza con la utilización de las osndas construidas a partir del polimorfismo obtenido, las que son especificas de complejo.

Integrate Study of a Bolivian Population Infected by Trypanosoma cruzi, the Agent of Chagas Disease

A cross section of a human population (501 individuals) selected at random, and living in a Bolivian community, highly endemic for Chagas disease, was investigated combining together clinical, parasitological and molecular approaches. Conventional serology and polymerase chain reaction (PCR) indicated an active transmission of the infection, a high seroprevalence (43.3 percent) ranging from around 12 percent in < 5 years to 94.7 percent in > 45 years, and a high sensitivity (83.8 percent) and specificity of PCR. Abnormal ECG tracing was predominant in chagasic patients and was already present among individuals younger than 13 years. SAPA (shed acute phase antigen) recombinant protein and the synthetic peptide R-13 were used as antigens in ELISA tests. The reactivity of SAPA was strongly associated to Trypanosoma cruzi infection and independent of the age of the patients but was not suitable neither for universal serodiagnosis nor for discrimination of specific phases of Chagas infection. Anti-R-13 response was observed in 27.5 percent only in chagasic patients. Moreover, anti-R13 reactivity was associated with early infection and not to cardiac pathology. This result questioned previous studies, which considered the anti-R-13 response as a marker of chronic Chagas heart disease. The major clonets 20 and 39 (belonging to Trypanosoma cruzi I and T. cruzi II respectively) which circulate in equal proportions in vectors of the studied area, were identified in patients' blood by PCR. Clonet 39 was selected over clonet 20 in the circulation whatever the age of the patient. The only factor related to strain detected in patients' blood, was the anti-R-13 reactivity: 37 percent of the patients infected by clonet 39 (94 cases) had anti-R13 antibodies contrasting with only 6 percent of the patients without clonet 39 (16 cases)

Selection of Trypanosoma cruzi clonal genotypes (clonet 20 and 39) isolated from Bolivian triatomines following subculture in liquid medium

Previous studies showed that two groups of Trypanosoma cruzi clonal genotypes named clonet 20 and clonet 39 were predominant in Triatoma infestans, the unique vector of Chagas disease in Bolivia. These groups of clones correspond to distinct genetic clusters. These clonets were detected in T. infestans and Rhodnius pictipes fecal samples before isolation and after culture by kDNA PCR (polymerase chain rreaction) and hybridization of the amplified products with clonet specific kDNA probes named 20 and 39 as previously reported. Forty eight T. infestans and three R. pictipes infected insects captured at random in different Bolivian departments were proceeded. As previously reported the direct identification of the two major clonets in fecal samples allowed the detection of abundant mixed infections: 41 percent in the original sample, however after culture, only 6 percent of mixed infections were detected. Among the 21 parasite stocks isolated from digestive tracts where mixed infections were initially detected (clonet 20 + 39) clonet 20 alone was detected in 81 percent of them. This result clearly showed that the culture step selected clonet 20 parasites over those belonging to clonet 39. The taxonomic status of the isolated stocks was also confirmed by isoenzyme typing, and correlation was observed between clustering topology and hybridization patterns with the probes 20 and 39.

Mexican Trypanosoma cruzi stocks: analysis of minicircle kDNA homologies by cross-hybridization

Homologies of minicircle kDNA of 27 Mexican stocks were studied by cross-hybridization with four kDNA probes derived from three reference stocks belonging to groups Trypanosoma cruzi I (SO34 cl4 and Silvio) and T. cruzi II (MN) and one Mexican stock. High homologies were only observed with Silvio (six stocks) and Mexican probes (11 stocks). After 30 min exposure (low homology) additional stocks were recognized with SO34 cl4 (three stocks) and Silvio (six stocks) probes; with the Mexican probe only five stocks remained non-reactive. All the stocks were typed by isoenzyme (16 loci) and Mexican stocks belonged to T. cruzi I. Hybridization patterns were not strictly correlated with the observed clustering and cross-hybridization of kDNA minicircles is not available to distinct Mexican stocks.

Ecogenetics of Triatoma sordida and Triatoma guasayana (Hemiptera: Reduviidae) in the Bolivian Chaco

Triatoma guasayana and two putative cryptic species pertaining to T. sordida complex (named groups 1 and 2) occur in sympatry in the Bolivian Chaco. Using multilocus enzyme electrophoresis and subsequent genetic analysis, our work assesses their population distribution and dispersal capacity in domestic, peridomestic, and silvatic environments. Our collections by light trap in the silvatic environment indicated a predominance of T. guasayana and T. sordida group 2 and a lesser abundance of T. sordida group 1 (ú 10 percent of the total of captures). Their similar distribution in two silvatic areas 80 km apart supports the hypothesis of their homogeneous dispersal through the Bolivian Chaco. The distribution of T. guasayana and T. sordida groups 1 and 2 was similar between silvatic environment and peridomestic ecotopes where 25 percent of positive places was occupied by two or three species. Bromeliads were confirmed as favorable shelter for T. guasayana but were free of T. sordida. T. sordida group 1 and to a lesser extent T. guasayana would be more invasive vectors for houses than T. sordida group 2. The spatial partition in the three species sampled in two distant sites suggested a reduced dispersive capacity

Immune response to Trypanosoma cruzi shed acute phase antigen in children from an endemic area for Chagas' disease in Bolivia

A field study of the immune response to the shed acute phase antigen (SAPA) of Trypanosoma cruzi was carried out in the locality of Mizque, Cochabamba department, Bolivia. Schoolchildren (266), with an average of 8.6ñ3.6 years, were surveyed for parasitological and serological diagnosis, as well as antibodies directed against SAPA using the corresponding recombinant protein in ELISA. The antibodies against SAPA were shown in 82 per cent of patients presenting positive serological diagnosis (IgG specific antibodies). The positive and negative predictive values were 0.88. Antibodies anti-SAPA were shown in 80.8 per cent of the chagasic patients in the initial stage of the infection (positive IgM serology and/or positive buffy coat (BC) test) and in 81.4 per cent of the patients in the indeterminate stage of the infection (positive IgG serology with negative BC and IgM tests). These results show that the anti-SAPA response is not only present during the initial stage of the infection (few months) but extends some years after infection.

Serodiagnóstico de la Trypanosomiasis Americana en una población infantil: análisis epidemiológico / Serodiagnostic of the trypanosiomasis american in a poblation childlike, epidemiological analysis

La enfermedad de Chagas, ha sido reconocida como un problema mayor de Salud Pública estos últimos años. En Bolivia, la población infantil presenta un alto riesgo de infección por Trypanosoma cruzi en zonas endémicas. En este estudio, 1479 sueros provenientes de niños de 4 a 10 años de una zona peri-urbana de la ciudad de Cochabamba fueron analizados. Dos pruebas serológicas (IFI) y (ELISA) fueron utilizadas para la detección de anticuerpos anti Trypanosoma cruzi y todos los individuos fueron evaluados por un cuestionario epidemiológico y un examen clínico. Un 5.6 por ciento de seropositividad fue encontrado en el total de individuos estudiados. Esta población comprende dos grupos de niños provenientes de dos estratos sociales diferentes. Esta situación esta correlacionada significativamente con el riesgo de infección por Trypanosoma cruzi. Por otra parte, el análisis estadístico realizado entre las variables clínicas, hematológicas y antropométricas en relación a la infección Trypanosoma cruzi, nos demuestra una dependencia neta entre estas variables, salvo algunos aspectos antoropométricos (talla, peso) y hemáticos (población de segmentados) que presentan una tendencia relativa