Intervention to prevent intestinal parasitic reinfections among Tarahumara indigenous schoolchildren in northern Mexico / Intervención para prevenir las reinfecciones parasitarias intestinales en niños indígenas tarahumara en edad escolar en el norte de México

OBJECTIVE: To assess the effectiveness of a 20-week, broad intervention to prevent reinfection by Ascaris lumbricoides (AL) and Giardia lamblia (GL) among indigenous schoolchildren in northern Mexico. METHODS: A prospective, comparative, ecological study. Two isolated boarding schools, each hosting 100-120 children, 4-15 years of age, were selected based on physical infrastructure: intervention school (IS), modern; control school (CS), deprived. After initial diagnosis, children with positive stool samples received supervised treatment with oral nitazoxanide. Diagnoses were made with at least one positive microscopic result from two serial samples using the Faust technique, as reported by the independent observations of two trained, laboratory technicians. Post-treatment samples were taken, and only those with negative results were followed-up. The intervention included infrastructure improvements/maintenance and an educational preventive program for children, parents, and school personnel; no activities were undertaken in the CS. RESULTS: Baseline prevalence for AL was 37.5 percent at the IS versus 16.6 percent at the CS (P < 0.01); and for GL, 51.7 percent versus 37.8 percent, respectively. At the IS, 35.7 percent did not speak Spanish, compared to 6.7 percent in the CS (P < 0.01). Cure rates were similar in both schools for AL (~ 98 percent) and GL (~ 80 percent). Final prevalence and reinfection rates for GL were 10.4 percent versus 10.8 percent, and 17.2 percent versus 21 percent at the IS and CS, respectively. No children were infected/reinfected with AL in either school. Follow-up rates were 80 percent-83 percent at the CS and 90 percent-95 percent at the IS. CONCLUSIONS: Infection/reinfection rates were similar at the schools after 20 weeks. Supervised treatment alone every semester could effectively control AL/GL infections in this indigenous setting.

OBJETIVO: Evaluar la eficacia de una intervención amplia de 20 semanas de duración para prevenir la reinfección por Ascaris lumbricoides y Giardia lamblia en niños indígenas en edad escolar del norte de México. MÉTODOS: Estudio prospectivo, de comparación y ecológico. Se seleccionaron dos internados geográficamente aislados, cada uno de los cuales alberga entre 100 y 120 niños de 4 a 15 años de edad, según su infraestructura física: una escuela moderna en la que se llevó a cabo la intervención y otra, precaria, que se empleó como control. Tras el diagnóstico inicial, los niños con resultados positivos en los análisis de las muestras de heces recibieron tratamiento supervisado con nitazoxanida oral. El diagnóstico se hizo con al menos un resultado microscópico positivo en dos muestras sucesivas con la técnica de Faust, según lo informado por las observaciones independientes efectuadas por dos técnicos de laboratorio capacitados. Se tomaron muestras postratamiento y solo se hizo el seguimiento de los niños con resultados negativos. La intervención incluyó mejoras y mantenimiento de la infraestructura y un programa educativo de prevención para los niños, los padres y el personal de la escuela; en la escuela de control no se llevó a cabo ninguna actividad. RESULTADOS: La prevalencia inicial de la infección por A. lumbricoides fue de 37,5 por cento en la escuela de la intervención frente a 16,6 por cento en la escuela de control (P < 0,01); la de G. lamblia, de 51,7 por cento frente a 37,8 por cento, respectivamente. En la escuela de la intervención 35,7 por cento no hablaba español, en comparación con 6,7 por cento en la escuela de control (P < 0,01). Las tasas de curación fueron similares en ambas escuelas para A. lumbricoides (aproximadamente 98 por cento) y para G. lamblia (aproximadamente 80 por cento). La prevalencia final y las tasas de reinfección para G. lamblia fueron de 10,4 por cento frente a 10,8 por cento en la escuela de la intervención y de 17,2 por cento frente a 21 por cento en la escuela de control. No hubo nuevas infecciones o reinfecciones con A. lumbricoides en ninguna de las escuelas. Las tasas de seguimiento fueron de 80 por cento a 83 por cento en la escuela de control y de 90 por cento a 95 por cento en la escuela de la intervención. CONCLUSIONES: Las tasas de infección o reinfección fueron similares en las dos escuelas después de 20 semanas. El tratamiento supervisado cada semestre como única medida controló eficazmente las infecciones con A. lumbricoides o G. lamblia en este entorno indígena.

Ascaris control: where do we stand?

Ascaris lumbricoides [the largest roundworm] is the most common and potentially serious pathogenic geo-helminth which is estimated of infect approximately 1300 million people. Its complications have been estimated cause 100, 000 deaths each year. World's population harbors 10, 000 million ascaris with a total burden of around 100 tons. Prevalence rates of the order of 16-97.6% have been recorded in many Asian and Latin countries. Ascariasis is a dirt disease, the load of which, unfortunately, its advancing, not receding. The toll is going high up because of increase in population and deterioration of sanitary conditions. Permanent freedom from the parasitions could not be expected till millions of residents of slum areas in developing countries succeed in getting clean environments. This does not seem to be an attainable goal in near future because the meager resource of these countries have already been over-stretched and provision of safe water and safe toilet facilities is a quite remote possibility

Development of Ascaris lumbricoides eggs from females eliminated after chemotherapy in man

The development of Ascaris lumbricoides eggs obtained from females eliminated after treatment of infected individuals with a single oral dose of the antihelminthic drugs thiabendazole (50 mg/kg - 33 patients) or levamisole (250 mg - independent of body weigth - 20 patients) was studied. Every female eliminated up to 72 h after treatment were dissected, the uterus isolated and sectioned into small fragments. The eggs were transferred to plastics tubes and incubated at 28 degrees centigrades in 0.1 N H2 SO4 for 100 days. Every 20 days, starting from the 20 th up to the 100 th day, the extent of egg embryonation ratio was determined. The culture of A. lumbricoides eggs obtained from females from patients treated with thiabendazole did not contain embryonated eggs until the final period of observation. In contrast, the eggs obtained from females eliminated by patients treated with levamisole (control) presented an embryonation rate of 0.0 - 98.0% in the same period

Ascaríase / Ascariasis

Verme conhecido desde a antiguidade e denominado pelos gregos como elmins strossyle. Os romanos o chamavam de Lumbricus teres, indicando que os confundiam com a "lombriga" comum da terra

Periodic deworming with pyrantel in an industrial township.

Between June 1986 and September 1987 a population of 100 families was dewormed every 3 months (quarter) by using a single dose of pyrantel. Stool samples were examined by Kato's thick smear method; height (m), weight (kg), hemoglobin concentration (g/dl) and clinical morbidity were recorded before each deworming treatment. Clinical morbidity was recorded in another 100 control families who did not receive anthelmlntics. There were 477 and 490 individuals in the study and the control families respectively. In the study group the prevalence of roundworm was reduced from 10.3% to to 0% and that of hookworm infection was reduced from 2.9% to 0% after 2 quarters. At the end of the 4th quarter the mean hemoglobin rose by 0.1 g/dl (P less than 0.01) and the mean BMI increased by 0.37 (P less than 0.01). There was a significant reduction in the clinical morbidity in the study group compared with the control group (P less than 0.05). There were no side effects reported to pyrantel treatment. Thus quarterly treatment with pyrantel was found to be effective in keeping roundworm and hookworm prevalence at 0% in an industrial township.

Epidemiología y prevención de la ascariasis en México: investigación preliminar / Epidemiology and prevention of ascariasis in Mexico: preliminary research

Ascaris lumbricoides es el parásito intestinal más común en el hombre. La temperatura y la humedad son críticos en determinar la maduración de los huevos hasta su estado infectante y su sobrevivencia, aunque la transmisión de la infección al hombre es dependiente también de los factores socioeconómicos. En México, la ascariasis representa un problema de salud pública, cuyos principales factores de riesgo son el hacinamiento, producción agrícola con uso amplio de la materia fecal como fertilizante, pobreza, analfabetismo, insalubridad ambiental y los patrones culturales. La frecuencia registrada fue más alta en los niños, de los cuales 20 a 80% estaban infectados. La ascariasis fue más prevalente en las áreas rurales principalmente del sureste y de los estados costeros tropicales. No hubo diferencia en la tasa de infección por sexos. La endemicidad depende no sólo de las presiones selectivas ambientales, sino que están reguladas también por la inmunidad de la población

Control trial of soil-transmitted helminthic infections with pyrantel pamoate.

Pyrantel pamoate at dosage of 10 mg per kilogramme body weight was given to each villager at 4-6 weeks intervals for three times. The infection rates of hookworms among those who received and did not received the drug decreased from 60.5% pre-treatment to 19.6% after the third treatment and then increased to 32.4% one year after the third treatment. Infection rates of A. lumbricoides and Strongyloides spp. among the villagers who received and did not received the drug decreased from 27.5% pre-treatment to 2.2% after the third treatment and then increased to 20.1% one year later for the former, while the latter decreased from 6.5% pre-treatment to 2.3% after the third treatment and 0.4% one year later. The infection rate of T. trichiura was found to increase as pyrantel pamoate had no effect on this nematode. The authors suggested that to obtain more satisfactory results the anthelmintic drug used must likewise be effective against T. trichiura particularly in areas where this nematode is a public health problem. It was also suggested that the duration of treatment should be prolonged.