Molecular characterization of Trypanosoma cruzi Mexican strains and their behavior in the mouse experimental model / Caracterização molecular de cepas mexicanas de Trypanosoma cruzi e seu comportamento no modelo experimental do camundongo

INTRODUCTION: For a long time, the importance of Chagas disease in Mexico, where many regarded it as an exotic malady, was questioned. Considering the great genetic diversity among isolates of Trypanosoma cruzi, the importance of this biological characterization, and the paucity of information on the clinical and biological aspects of Chagas disease in Mexico, this study aimed to identify the molecular and biological characterization of Trypanosoma cruzi isolates from different endemic areas of this country, especially of the State of Jalisco. METHODS: Eight Mexican Trypanosoma cruzi strains were biologically and genetically characterized (PCR specific for Trypanosoma cruzi, multiplex-PCR, amplification of space no transcript of the genes of the mini-exon, amplification of polymorphic regions of the mini-exon, classification by amplification of intergenic regions of the spliced leader genes, RAPD - (random amplified polymorphic DNA). RESULTS: Two profiles of parasitaemia were observed, patent (peak parasitaemia of 4.6×10(6) to 10(7) parasites/mL) and subpatent. In addition, all isolates were able to infect 100 percent of the animals. The isolates mainly displayed tropism for striated (cardiac and skeletal) muscle. PCR amplification of the mini-exon gene classified the eight strains as TcI. The RAPD technique revealed intraspecies variation among isolates, distinguishing strains isolated from humans and triatomines and according to geographic origin. CONCLUSIONS: The Mexican T. cruzi strains are myotrophic and belong to group TcI.

INTRODUÇÃO: Durante muito tempo, foi questionada a importância da doença de Chagas no México onde muitos a consideravam um padecimento exótico. Considerando a grande diversidade genética existente, entre os isolados de Trypanosoma cruzi, a importância da caracterização biológica desses e o escasso número de informações sobre os aspectos clínicos e biológicos da doença de Chagas no México, o objetivo deste trabalho foi realizar a caracterização biológica e molecular de isolados de Trypanosoma cruzi originários de diferentes áreas endêmicas deste país, principalmente do Estado de Jalisco. MÉTODOS: Oito cepas mexicanas de Trypanosoma cruzi foram caracterizadas biologicamente e geneticamente (PCR específica para Trypanosoma cruzi, PCR-multiplex, amplificação do espaço não transcrito dos genes do mini-exon, amplificação das regiões polimórficas do gene do mini-exon, classificação pela amplificação de regiões intergênicas dos genes do spliced leader, RAPD - random amplified polymorphic DNA). RESULTADOS: Foram observados dois tipos de parasitemia: patente com picos máximos de parasitemia entre 4,6x10(6) e 10(7) parasitas/mL e subpatente. Além disso, todos os isolados foram capazes de infectar 100 por cento dos animais. Observou-se tropismo predominante pelo músculo estriado (cardíaco e esquelético). As técnicas de PCR do gene do mini-éxon classificaram as oito cepas como TcI e a técnica de RAPD mostrou variação intra-especifica das mesmas, separando as cepas isoladas de humanos daquelas de triatomíneos e por origem geográfica. CONCLUSÕES: As cepas mexicanas de Trypanosoma cruzi são miotrópicas e correspondem ao TcI.

Prevalência de triatomíneos (Hemíptera: Reduviidae: Triatominae) infectados por Trypanosoma cruzi: sazonalidade e distribuição na região Ciénega do Estado de Jalisco, México / Prevalence of triatomines (Hemíptera: Reduviidae: Triatominae) infected by Trypanosoma cruzi: seasonality and distribution in the Ciénega region of the State of Jalisco, Mexico

As características físico-geográficas da região Ciénega, Jalisco, México a tornam propícia para transmissão do Trypanosoma cruzi, causador da doença de Chagas. Este trabalho caracteriza a prevalência de triatomíneos infectados pelo parasita, sua sazonalidade e distribuição nesta região. Foram analisados 328 triatomíneos no período de janeiro de 2005 a junho de 2007 procedentes de 13 municípios da região, sendo abril, maio e junho os meses de maior captura. Dos triatomíneos analisados, 57,3 por cento foram positivos para Trypanosoma cruzi, correspondendo 15,4 por cento para a área urbana e 84,6 por cento para a área rural. A espécie mais freqüente foi Triatoma longipennis e a mais parasitada foi Triatoma barberi com índice de infecção de 83,3 por cento quando comparada a Triatoma longipennis (67,5 por cento) (p<0,05). A infecção natural dos vetores capturados pode indicar alta exposição das pessoas ao Trypanosoma cruzi. O achado recente do Triatoma dimidiata positivo nesta região, sugere a adaptação de novas espécies às condições ecológicas destas populações.

The physical and geographical characteristics of the Ciénega region, Jalisco, Mexico make it suitable for transmission of Trypanosoma cruzi, the causative agent for Chagas disease. This study characterizes the prevalence of triatomines infected by this parasite, their seasonality and their distribution in this region. A total of 328 triatomines were evaluated between January 2005 and June 2007, from 13 municipalities in the region. April, May and June were the months with the highest capture levels. Among the triatomines examined, 57.3 percent were positive for Trypanosoma cruzi, corresponding to 15.4 percent in urban areas and 84.6 percent in rural areas. The species with greatest prevalence was Triatoma longipennis and the species with the highest parasitism rate was Triatoma barberi, with an infection rate of 83.3 percent, whereas the rate for Triatoma longipennis was 67.5 percent (p<0.05). This natural infection in the captured vectors may indicate that individuals in this region have high exposure to Trypanosoma cruzi. The recent findings of positive Triatoma dimidiata in this region suggest that new species are becoming adapted to the ecological conditions of these populations.

Biology of three species of North American Triatominae (Hemiptera: Reduviidae: Triatominae) fed on rabbits

Aspects related to hatching, lifetime, number of blood meals for molting, mortality, feeding time, and postfeeding defecation delay were evaluated and compared in each instar of three North American Triatominae: Triatoma gerstaeckeri, Triatoma lecticularia and Triatoma protracta, all of them fed on rabbits. No significant differences (p > 0.05) were found among the three species regarding mean hatching rate, which was close to 20 days. Egg-to-adult development times were significantly shorter (p < 0.05) for T. lecticularia. Number of blood meals for molting to next instar ranged from one to five for T. protracta, and from one to six for T. gerstaeckeri and T. lecticularia. Mortality rates were higher in younger nymphs of T. lecticularia and T. protracta, while rates in T. gerstaeckeri were higher in fifth-instar nymphs. Mean feeding time was longest in T. gerstaeckeri, followed by T. lecticularia. More than twice the number of T. gerstaeckeri nymphs completed the development process, if compared to the nymphs from the other two species. Defecation delay was less than 10 min for T. lecticularia, T. protracta and the youngest nymphs of T. gerstaeckeri. Results point out that these three species may be important potential vectors of Trypanosoma cruzi for human populations, in areas of Mexico where these species are currently present.

Biology of three species of the Meccus phyllosomus complex (Hemiptera: Reduviidae: Triatominae) fed on blood of hens and rabbits

Aspects related to hatching, life time, number of blood meals to molt, mortality, feeding time and postfeed defecation delay for each instar of Meccus phyllosomus, M. mazzottii, and M. bassolsae, life-cycle were evaluated and compared in two cohorts of each of those three species, fed on hens or rabbits. No significant (p > 0.05) differences were recorded among cohorts fed on hens respect to cohorts fed on rabbits in M. phyllosomus and M. mazzottii and the average time of hatching was 21.5 days for cohorts fed on hens and 22.5 for cohorts fed on rabbits. Average egg-to-adult development times were no significant (p > 0.05) different between both cohorts of M. phyllosomus and M. mazzotti, independent of the blood meal source. The average span in days for each instar fed on hens was not significantly different to the average span for each instar fed on rabbits, when comparisons were made by species. The number of blood meals at each nymphal instar varied from 1 to 6 in both cohorts of each species. The mortality rates were higher on older nymphs, in both cohorts of M. phyllosomus and M. bassolsae, whereas they were higher on first instar nymphs on M. mazzottii. Mean feeding time was no significant (p > 0.05) different in triatomines fed on hens or fed on rabbits, when each species were compared separately. A similar number of nymphs of each cohort, completed the cycle. Defecation delay was no significant (p > 0.05) different when cohorts fed on hens and fed on rabbits were compared by species. Most of the studied parameters showed no significant (p > 0.05) differences among those cohorts fed on hens and for fed on rabbits, which could mean a high degree of association of those species with birds as much as mammals, under wild conditions, increasing their capacity to colonize human dwellings.

Prevalencia de deficiencia de hierro y yodo, y parasitosis en niños de Arandas, Jalisco, México / Prevalence of iron and iodine deficiency and parasitosis in children from Arandas, Jalisco, Mexico

Objetivo. Estimar la prevalencia de deficiencia de hierro, yodo y parasitosis en niños que asisten al Instituto Alteño para el Desarrollo de Jalisco (Inadej), Arandas, Jalisco, México. Material y métodos. Estudio transversal efectuado entre 1997 y 1999 con 432 niños de 12 a 120 meses de edad, de nuevo ingreso al Inadej. Se determinaron variables hematológicas, yodo en orina y presencia de parásitos. Se utilizaron las pruebas Ji cuadrada y t de Student en variables no paramétricas y paramétricas. Resultados. Hubo más anemia (20 vs 7.4 por ciento p=0.007) y deficiencia de hierro (60.9 vs 44.4 por ciento p=0.02) en prescolares que en escolares. El 29 por ciento presentaron deficiencia de yodo (10.5 por ciento moderada o grave) y 47.2 por ciento parasitosis. Predominaron G. lamblia y E. histolytica. Bajo salario, sexo masculino y no tener seguridad social se asociaron con parasitosis. Conclusiones. La elevada prevalencia de deficiencia de hierro, yodo y parasitosis obliga al sector salud estatal a ejecutar medidas eficaces para abatir estas enfermedades prevenibles.

Objective. To estimate the prevalence of iron deficiency, iodine deficiency and parasitosis in children attending the Instituto Alteño para el Desarrollo de Jalisco ((Highlands Institute for Development of Jalisco State, INADEJ), Arandas, Jalisco, Mexico. Material and Methods. A cross-sectional study was conducted between 1997 and 1999, among 432 children aged 12 to 120 months attending the INADEJ. Measurements included hematological values, urine iodine concentration, and presence of parasites. Student's t test chi square tests were used for parametric and non-parametric analysis. Results. The prevalence figures of anemia (20 vs 7.4 percent, p=0.007) and iron deficiency (60.9 vs 44.4 percent, p=0.02) were higher in preschool than in school children. Iodine deficiency was found in 29 percent (10.5 percent moderate or severe) and parasitosis in 47.2 percent of children, mainly E. histolytica (30.2 percent) and G. lamblia (28.9 percent). Low income, male gender and lack of social security policy holding were associated to parasitosis. Conclusions. The high prevalence rates of iron deficiency, iodine deficiency, and parasitosis, should be addressed by state health services with effective interventions to restrain these preventable diseases.

Distribución de los vectores de la enfermedad de Chagas (hemiptera: Reduviidae: Triatominae), en el estado de Jalisco, México / Distribution of Chagas' disease vectors (Hemíptera: Reduviidae: Triatominae), In the estate of Jalisco, Mexico

Introducción. Los triatominos, conocidos comúnmente con el nombre de "Chinche hocicona" en Jalisco. México juegan un papel importante en la transmisión de la Enfermedad de Chagas ya que al picar para alimentarse de sus hospederos, defecan, depositando en las deyecciones al Trypanosoma cruzi causante de esta enfermedad. La existencia de estos vectores en México han sido reportada pero su distribución en el estado de Jalisco es poco conocida. Objetivo. Conocer las especies y distribución de los vectores enfermedad de Chagas y su positividad a Trypanosoma cruzi en el estado de Jalisco. Material y Métodos. Se llevó a cabo un estudio de tipo observacional, descriptivo y transversal, en el que se utilizaron muestras probalísticas para los municipios en los que se realizó el trabajo, la captura fue manual, diurna, auxiliándose con lámparas de mano durante 1h/hombre/vivienda. Resultados. Se colectaron 8 especies del género Triatoma: Triatoma barberi, T. Brailovskyi, T. dimidiata, T. longipennis, T. mazzottii, T. pallidepennis, T. phyllosoma y T. picturata. La mayoría de los muncipios son lugares nuevos de ubicación de las especies en el estado, la especie más distribuida y más parasitada en los municipios estudiados fue Triatoma longipenis Usinger y 27 (53 por ciento) municipios fueron en donde se encontraron triatomino infectados con Trypanosoma cruzi en éstos, hacen posible la existencia de la enfermedad en el estado de Jalisco

Serological follow-up of trypanosoma cruzi infection from 1987 to 1994 in 32 countries of the state of Jalisco, Mexico: preliminary report

Em 1987, a Universidade de Guadalajara realizou um inquérito sorológico sobre a prevalência da doença de chagas em 124 municípios do estado de Jalisco, México, chegando a uma taxa de 21.6 por 100 habitantes. Entre dezembro de 1993 e junho de 1994, foram estudados 2238 indivíduos de 32 municípios da área rural desse mesmo estado. Encontraram 276 positivos (12,33 por cento) e 1962 negativos (87,66 por cento). Entretanto, as séries de diferenças sorológicas foram muito marcantes, uma vez que dos 655 indivíduos que testaram positivos em 1987, 276 permaneceram positivos, enquanto 50 (7,63 por cento) tornaram-se soro-negativos. Näo houve falha de técnica laboratorial. Acredita-se que, ou a resposta imune dos mexicanos é diferente, ou entäo, que a virulência das cepas mexicanas de trypanosoma cruzi näo é täo intensa quanto aquela encontrada em países sul-americanos.

Prevalencia de infeccion a Trypanosoma cruzi en donadores de sangre en el estado de Jalisco, Mexico / The prevalence of Trypanosoma cruzi infection in blood donors in the state of Jalisco, Mexico

Durante el periodo de Octubre de 1991 a Marzo de 1992, se tomaron 3419 muestras de donadores de sangre de 12 localidades rurales y de 8 hospitales urbanos a los que se les realizó un estudio serológico mediante la reacción de hemaglutinación indirecta encontrádose anticuerpos contra Trypanosoma cruzi em 44 indivíduos 39 masculinos y 5 femininos. El 90,9 por cento de donantes fueron masculinos. De acuerdo a su procedencia, el 73,5 por ciento fué del área urbana y el 26,5 por ciento del área rural. De acuerdo a los resultados el riesgo de transmisión de T. cruzi por transfusion sanguinea está latente por la creciente urbanización de la enfermedad de Chagas