Enfermedad de Chagas en México / Chagas disease in Mexico

Resumen México es un país endémico para la enfermedad de Chagas, donde dos terceras partes del territorio pueden ser consideradas en riesgo de transmisión vectorial, es decir que 1'100,000 individuos podrían estar infectados con Trypanosoma cruzi y 29'500,000 en riesgo de contraer la infección. En la morbimortalidad del padecimiento son importantes las características de la vivienda, condiciones biológicas, ambientales y factores socioculturales. El tamizaje en bancos de sangre, a la fecha, es de observancia obligatoria con una cobertura mayor al 92%. El diagnóstico no se establece frecuentemente debido al desconocimiento de la enfermedad por parte del personal de salud y de la población. La fase aguda generalmente pasa desapercibida y en la crónica, la patología se presenta principalmente en el corazón, con evolución lenta. La patogénesis de la miocardiopatía crónica es muy compleja y se presentan lesiones con mayor frecuencia en el sistema nervioso autónomo y miocardio, lo que genera trastornos en la conductibilidad y contractilidad del órgano. Se describen los principales mecanismos patogénicos implicados en el desarrollo de la enfermedad.

Abstract Mexico is a country endemic for Chagas disease in which two thirds of the territory can be considered at risk of vector-borne infection. This means that 1.1 million people could be infected with Trypanosoma cruzi and 29.5 million at risk of infection. Dwelling characteristics of poverty in these rural areas linked with biological conditions, lifestyle, environmental and sociocultural factors are important in the morbidity and mortality of the disease. Nowadays, the screening for the parasite is mandatory and at least 92% of blood banks are covered. The inadequate knowledge of the disease by the health personnel and the population limits the possibility of the diagnosis. The acute phase of the disease courses undetected. The main affected organ in Chagas disease is the heart, with a slow evolution; the pathogenesis of chronic cardiomyopathy is complex and lesions occur mainly in the autonomic nervous system and myocardium leading to disturbances in the conductivity and contractility of the organ. The main pathogenic mechanisms involved in the development of the disease are described.

Evaluación de la función y sincronía de la contracción ventricular en pacientes con enfermedad de Chagas en estadio de latencia / Evaluation of the function and ventricular synchrony in patients with latency stage of Chagas' disease

OBJECTIVE: To compare the left ventricular function and the ventricular synchrony in patients with Chagas disease in latency stage respect to a control group. METHODS: We analyze a prospective, comparative, transversal and non randomized study of the left ventricular function (LVF) and the ventricular contraction synchronicity (VCS) in 36 subjects with positive serology for Chagas disease (18 males and 18 females), with mean of 15 +/- 5-years-old. The findings were compared with respect to 23 control volunteers (11 males and 12 females) with mean of 28 +/- 5-years-old. LVF and VCS were evaluated using equilibrium radionuclide angiography images (ERNA). The comparison of both Chagas and control populations was carried out by t Student test for independent samples, considering a statistically significant value of p < 0.05. RESULTS: The parameters of the ventricular function and the ventricular synchronicity in subjects with positive serology for Chagas disease were not statistically different with respect to the parameters of the control group. However, although they have a homogeneous contraction, the mean time of contraction for the right and the left ventricle is statistically smaller with respect to the control group. CONCLUSIONS: In clinically incipient stages of Chagas disease we do not found abnormalities in the ventricular function and the ventricular synchronicity. It's necessary to consider the follow up of the studied populations using indices for the identification of abnormalities of the autonomic nervous system.

Influence of temperature and humidity on the biology of Triatoma mexicana (Hemiptera: Reduviidae: Triatominae) under laboratory conditions

Several biological parameters related to the Triatoma mexicana life-cycle were evaluated in this study. Three cohorts were maintained under different combinations of temperature and relative humidity (RH): 25ºC/50 percent RH; 25ºC/75 percent RH; and 30ºC/75 percent RH. Observed hatching rates varied from 49-57.5 percent whereas the average time of hatching varied from 19.5-22.7 days. In the three cohorts studied, the mean time-lapse between presentation of the blood meal and the beginning of feeding was less than 5 min in all instars; the mean feeding time was longer than 10 min in all the instars; the post-feed defecation delay was over 10 min in all the instars. Less than 50 percent of nymphs in each cohort completed the cycle and the average time from 1st instar nymph to adult was more than 255 days for the three cohorts. The number of blood meals before molt at each nymphal instar varied from 1-9. Our results appear to indicate a lack of influence of temperature and RH on the biological parameters of T. mexicana that were studied, which could reflect the adaptation capacity of this species. We also conclude that T. mexicana can not be considered an effective transmitter of Trypanosoma cruzi to human populations in areas where this species is currently present.

Triatoma mexicana (Hemiptera: Reduviidae) in Guanajuato, Mexico: house infestation and seasonal variation

Triatoma mexicana was described by Herrich-Schaeffer in 1848. In 1940, a male specimen was found in Hidalgo. In 1970, this species was recorded in the state of Queretaro. Later, it was registered in Guanajuato and San Luis Potosi. In the present paper we performed an investigation in 545 dwellings from three counties in the state of Guanajuato, Mexico, from March 2003 to May 2004. The search and capture of triatomines were seasonally performed indoors and outdoors. Entomological indexes were calculated. The risk and no risk relations between triatomine presence and housing construction materials were analyzed. Fourteen triatomines were collected indoors and 151 outdoors. The vectors were collected in houses built with either risky and non-risky materials. Adults go indoors but do not settle there, hence, no relationship was found between the building materials and infestation of houses. Conventional interventions like house improvement or insecticide spraying are not efficient for the control of T. mexicana, because its developmental cycle is accomplished outdoors in the area surrounding the houses.

Insecticide and community interventions to control Triatoma dimidiata in localities of the State of Veracruz, Mexico

Three different interventions to control Triatoma dimidiata in the State of Veracruz were implemented: X-1 = whole dwelling spraying, X-2 = middle wall spraying, X-3 = household cleaning. Cyfluthrin was sprayed 3 times with 8 month intervals. After each spraying, insects were collected and sent to the laboratory to be recorded and to determine genus and species of the adult triatomine bugs, and nymphs were counted. Trypanosoma cruzi presence was determined. With X-1, the infestation, colonization, and natural infection indexes were reduced to 0 percent in the 3 localities, with respect to t0. With X-2, the infestation index was reduced to 10 percent at t3 in 3 localities; the colonization index was reduced to 0 percent in only 1 locality at t3, and the natural infection index was reduced to 0 percent at t3. With X-3 the 3 indexes were not effectively reduced but they decreased with respect to the baseline study. Insecticide application to the whole dwelling is a more efficient intervention than its application to only the lower half of the walls and to the cleaning of houses.

Parasite search in strawberries from Irapuato, Guanajuato and Zamora, Michoacan (Mexico)

A seasonal research was carried out in Irapuato, Guanajuato and Zamora, Michaocan, Mexico, the location of the most important producers of strawberries, in order to assess fecal contamination through the findig of protozoan cysts and helminth eggs, specifically of Taenia sp eggs. Three techniques were used: direct observation, flotation and sedimentation. Low numbers of protozoan cysts and only one Ascaris egg were found. What is most interesting is that no Taenia eggs were identified. Results indicate that although strawberries are contaminated with human feces, contamination is minimal

Dermatitis verminosa reptante / Dermatitis cutaneous larva migrans

Se comunica un brote epidémico de Larva migrans cutánea, posterior a lluvias intensas al paso del huracán Celia, en siete estudiantes y un profesor de la Facultad de Ciencias. El diagnóstico se estableció clínicamente; se realizaron frotes sanguíneos para cuantificación de eosinófilos. Fueron tratados con albendazol a dosis convencionales y tiabendazol tópico

Detección de necesidades de educación médica continua durante 1984, en la población que asiste a cursos en la Facultad de Medicina UNAM / Detection of needs of medical continuing education during 1984, of the students of the courses of the Facultdad de Medicina UNAM

Se presentan los resultados de una encuesta de necesidades de educación médica contínua, aplicada a los profesionales del equipo de salud que asistieron al curso de actualización con aval de la UNAM; durante el año de 1984. Asistieron 1713 profesionales de los cuales la gran mayoría fueron médicos generales. El área clínica predominó sobre el área básica, auxiliares de diagnóstico y sociomedicina. Se prefirieron cursos teórico-prácticos, impartidos de preferencia en el turno matutino, 6 horas diarias por una semana. La sede universitaria más solicitada fué el palacio de medicina. Se presentan las sugerencias del contenido temático, agrupadas por áreas de la medicina. Finalmente se discuten los resultados obtenidos