OBJETIVO: Evaluar la prevalencia e intensidad de las infecciones por geohelmintos en niños de dos comunidades hiperendémicas tratadas con técnicas antihelmínticas diferentes: una con tratamiento selectivo o individual, y la otra con tratamiento masivo reiterado. MÉTODOS: La población estuvo compuesta por 909 niños de uno u otro sexo, con edades entre 2 y 13 años, que vivían en dos comunidades marginales de la ciudad: Las Lomas y El Abasto, Santa Fe, Argentina. Se realizó un trabajo prospectivo longitudinal, cuasiexperimental, de comunidades. Durante los 22 meses del estudio se llevaron a cabo 5 controles parasitológicos, evaluados desde el punto de vista cualitativo y cuantitativo, y se dispensaron tratamientos antihelmínticos después de los controles 0, 2, 3 y 4. En Las Lomas se aplicó el tratamiento selectivo a los casos con diagnóstico parasitológico positivo que integraban la muestra A (n = 55) y en El Abasto, tratamiento masivo a todos los niños, incluidos los integrantes de la muestra B (n = 50). Ambas muestras fueron escogidas para realizar los controles. RESULTADOS: Se comprobó una prevalencia e intensidad de la infección por Ascaris lumbricoides significativamente mayor en El Abasto. No se detectaron diferencias para Trichuris trichiura. Al comparar las prevalencias y cargas parasitarias de A. lumbricoides entre los controles realizados dentro de una misma comunidad (inicio y final del estudio) no se observaron diferencias significativas en la muestra A, aunque sí en la muestra B. En cuanto a T. trichiura, se detectaron diferencias significativas entre ambos controles en las dos muestras. CONCLUSIONES: Solo el tratamiento masivo y reiterado logró disminuir eficaz y significativamente la prevalencia y la carga parasitaria de A. lumbricoides durante el período estudiado.

OBJECTIVE: To compare the prevalence and intensity of soil-transmitted nematode infection among children from two hyperendemic communities who were treated with antihelminthic drugs under two different regimens: selective or individual treatment was administered to members of one of the communities, and repeated mass treatment was given to the control community. METHODS: The study population was comprised of 909 children of both sexes between the ages of 2 and 13 from two peri-urban communities: Las Lomas and El Abastos, both in Santa Fe, Argentina. A prospective, longitudinal, quasi-experimental study was carried out in these communities. During the 22-month study period, 5 parasitologic controls were performed and results were qualitatively and quantitatively examined. Treatment with antihelminthic drugs was given at controls 0, 2, 3, and 4. At Las Lomas, selective treatment was administered to those in sample A (n = 55) who were positive for parasites; in El Abasto, mass treatment was given to all children, including those in sample B (n = 50). Both samples received follow-up. RESULTS: The prevalence and intensity of A. lumbricoides infections were found to be significant in El Abasto. No differences were detected in the case of T. trichiura. When prevalence and parasitic burden of A. lumbricoides were compared among controls within a single community (at the beginning and end of the study), no significant differences were observed in sample A, but a significant difference was seen in sample B. Insofar as T. trichiura is concerned, there were significant differences among controls in both samples. CONCLUSIONS: Only repeated and massive treatment significantly lowered the prevalence and intensity of A. lumbricoides infections during the study period.