RESUMEN
A seroepidemiologic survey conducted in 1971 in the rural Pacific coastal community of Chila in the Mexican state of Oaxaca showed an unusually high prevalence of antibody against the Chagas' disease agent Trypanosoma cruzi. Further studies were undertaken in 1973 and 1981 to (1) determine the pathologic impact of T. cruzi infection in humans, (2) investigate the natural history of the disease, (3) confirm that serologically positive persons were parasitologically positive, and (4) evaluate whether T. cruzi transmission continued into the next decade. This article reports results derived from those studies.
PIP: In 1971, health workers drew blood samples from 238 people living in the rural Pacific coastal village of Chile in Oaxaca State, Mexico to determine seroprevalence of antibodies against Trypanosoma cruzi--the parasite responsible for Chagas' disease. Seroprevalence was 5% in 16 year old children, but increased from 41% to 62% to a peak of 78% for 16-19, 20-29, and 30-39 year olds respectively then fell to 68% for 40-49 year olds only to climb again to 75% in 50-59 year olds and fell again to 47% for =or 60 year olds. Overall seroprevalence for adults was 67%. By 1981, adult seroprevalence had fallen to 33% and childhood prevalence to 0.7%. The very low levels of T. cruzi antibodies in children corresponded with insecticide (DDT) spraying for malaria control and with the disappearance of triatomine bugs from Chile. Medical histories revealed that seropositive individuals were more likely to exhibit acute signs and symptoms of initial bite lesions (Romana's sign), furuncle like skin lesions (Chagoma), and facial or body edema (p.05). They also tended to suffer from chronic fatigue and difficult breathing while lying down (p.05). 1973 electrocardiogram (ECG) results showed that seropositive individuals were significantly more likely to have complete right bundle branch block (p.005) and premature ventricular contractions (p.05) than seronegative individuals. There were no seroconversions among 57 people examined with ECGs between 1971-1983. Even though more seropositives (21%) experienced a progression of ECG abnormalities (3% rate/year) than seronegatives (7%), the difference was not significant. Despite reductions in seroprevalence and in triatomine bug population, serologic surveillance and monitoring to detect repopulation of houses by the bugs should be maintained.
Asunto(s)
Enfermedad de Chagas/epidemiología , Adolescente , Adulto , Animales , Anticuerpos Antiprotozoarios/sangre , Bloqueo de Rama/epidemiología , Bloqueo de Rama/etiología , Enfermedad de Chagas/complicaciones , Enfermedad de Chagas/inmunología , Niño , Preescolar , Estudios Transversales , Electrocardiografía , Femenino , Estudios de Seguimiento , Humanos , Lactante , Estudios Longitudinales , Masculino , México/epidemiología , Persona de Mediana Edad , Prevalencia , Salud Rural , Trypanosoma cruzi/inmunologíaRESUMEN
Antibody prevalence to Toxoplasma gondii among residents of a Pacific coastal region of Oaxaca State, Mexico is among low rates reported worldwide. From 60 small, rural communities, 3229 persons from ages 6 months to over 70 years provided blood specimens that were stored on filter papers. 124 (3.8%) of the eluates were seropositive (positive titer greater than 1:256) in the indirect hemagglutination test, and 43 (1.3%) had titers greater than 1:1024. Seropositive rates increased by age group and females were positive twice as often as males. There was no difference in rates for persons who lived at sea level, compared to those who lived between 600 and 1800 meters. In two small communities in which the number of persons tested were a large percentage of the total population, seropositive rates were 1.0 and 1.9%, respectively. The probable explanation for these low rates is the near absence of cats and paucity of meat in the diet. By contrast, sera tested from 479 persons living about 150 km to the east in the coastal, urban towns of Tehuantepec of Salina Cruz showed positive reactions among 122 (125.5%), and 71 (14.8%) had titers less than 1:1024. These people had a higher standard of living, more meat in their diet, and a few cats.
Asunto(s)
Anticuerpos Antiprotozoarios/sangre , Toxoplasma/inmunología , Toxoplasmosis/epidemiología , Adolescente , Adulto , Anciano , Altitud , Animales , Gatos , Niño , Preescolar , Etnicidad , Femenino , Encuestas Epidemiológicas , Humanos , Lactante , Masculino , México/epidemiología , Persona de Mediana Edad , Prevalencia , Toxoplasmosis/sangre , Toxoplasmosis/inmunologíaRESUMEN
Las encuestas serológicas realizadas en 1971 en el estado de Oaxaca, México, revelaron niveles desusadamente altos de anticuerpos a Trypanosoma cruzi, agente de la enfermedad de Chagas, en ciertas comunidades. En Cerro del Aire resultaron positivas 76% de las 248 personas mayores de 20 años sometidas a pruebas serológicas. Sin embargo, solo 2% de los menores de 10 años dieron resultados seropositivos y la ausencia del vector indicó que la infección no se había transmitido en esa comunidad por un período de cerca de 10 años. En 1973 y 1980 se emprendieron nuevos estudios con fines de: 1) determinar los efectos patológicos de la infección en el hombre; 2) investigar la historia natural de la enfermedad; 3) comprobar que las personas con reacciones serológicas positivas eran parasitológicamente positivas, y 4) comparar los métodos de aislamiento de T. cruzi. De los 237 habitantes de Cerro del Aire (124 eran menores de 16 años) que se sometieron a las pruebas de hemaglutinación indirecta, aglutinación directa y fijación del complemento en 1980, 35% fueron seropositivos. Los exámenes clínicos y electrocardiográficos mostraron diferencias significativas entre 111 personas seropositivas y 65 seronegativas. Los sujetos seropositivos que proporcionaron sus historiales clínicos notificaron lesiones tipo chagoma o Romaña con más frecuencia que los seronegativos (p<0,02). Las diferencias también fueron significativas respecto de los dolores precordiales (p<0,05) y palpitaciones (p<0,02). Los electrocardiogramas revelaron uno o más tipos de anormalidades en 46% de los sujetos seropositivos, pero solo en 22% de los seronegativos (p<0,005). El bloqueo de rama derecha se presentó en 12% de los seropositivos y en 2% de los seronegativos (p<0,02), y las extrasístoles ventriculares en 6% de seropositivos y en ninguno de los seronegativos (p<0,05)...
Asunto(s)
Recién Nacido , Lactante , Preescolar , Niño , Adolescente , Adulto , Persona de Mediana Edad , Humanos , Masculino , Femenino , Enfermedad de Chagas/epidemiología , Pruebas Serológicas , Electrocardiografía , Estudios Longitudinales , MéxicoAsunto(s)
Cardiomiopatía Chagásica/epidemiología , Adolescente , Adulto , Bloqueo de Rama/diagnóstico , Cardiomiopatía Chagásica/diagnóstico , Cardiomiopatía Chagásica/transmisión , Niño , Preescolar , Electrocardiografía , Femenino , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Estudios Longitudinales , Masculino , México , Persona de Mediana Edad , Población Rural , Pruebas Serológicas , Trypanosoma cruzi/aislamiento & purificaciónRESUMEN
Se efectuaron dos encuestas seroepidemiologicas en el estado de Chiapas, Mexico, con objeto de obtener informacion sobre la distribucion geografica de la enfermedad de Chagas. Durante la primera, que se hizo a toda la extension de dicho estado, tornaron 1.827 muestras de sangre de 29 comunidades.Se encontraron pruebas serologicas de infeccion en cinco de las comunidades, que estaban ubicadas en una zona semitropical de la region noreste de Chiapas.Fueron seropositivas 28 por ciento de las personas investigadas (80 en total) en la poblacion Agua Azul Chiquito, 14 por ciento (73 en total) de la de Leon Brindis, y 5.8 por ciento (353 en total) de las de otras tres comunidades. De los 150 ninos menores de diez anos de edad investigados en cinco comunidades, 4 por ciento fueron seropositivos, lo que indica que probablemente prosigue la transmision.En la segunda encuesta efectuada en 28 comunidades de la municipalidad de Margaritas, solamente cinco (0,3 por ciento) de las 1.476 personas investigadas fueron seropositivas
Asunto(s)
Humanos , Masculino , Femenino , Enfermedad de Chagas , Pruebas Serológicas , Encuestas Epidemiológicas , MéxicoAsunto(s)
Enfermedad de Chagas/epidemiología , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , México , Persona de Mediana EdadRESUMEN
A serologic survey was conducted in south-western Mexico to obtain information on human experience with arbovirus infections. Sera were collected from two semitropical areas along the Pacific coast of Oaxaca State, two mountain areas above 1,700 meters and the interior valley at 1,500 meters. Of the 610 sera tested for group A antibody, 4.9 per cent were positive in the hemagglutination-inhibition (HI) test to Venezuelan (VE), 11 per cent to Eastern, and none to Western encephalitis viruses. In neutralization tests the antibody was shown to be probably due to VE virus infections. When sera were screened for group B antibodies in the HI test, 32 per cent were positive with St. Louis encephalitis (SLE), 19 per cent with Ilhéus, and 4 per cent with yellow fever viruses. The pattern of reactions suggested that SLE or an antigenically related virus was responsible for the antibody detected. An unusually high rate was found in a mountain area at 2,000 meters: 41 per cent of 113 persons tested were seropositive to SLE. Of 493 sera screened by complement-fixation test, 6 per cent were positive to Nepuyo, 4 per cent to Patois, and 3 per cent to Tlacotalpan viruses.