Therapeutic response of Plasmodium vivax to chloroquine in Riberalta, Guayaramerín and Yacuiba, Bolivia Respuesta terapéutica del Plasmodium vivax a la cloroquina, en Riberalta, Guayaramerín y Yacuiba, Bolivia

Introduction. The knowledge of the therapeutic efficacy of chloroquine for Plasmodium vivax infections improves the capacity for surveillance of anti-malarial drug resistance. Objective. To evaluate the therapeutic efficacy of chloroquine as treatment for uncomplicated Plasmodium vivax malaria in Riberalta, Guayaramerin and Yacuiba, Bolivia. Materials and methods. An In vivo efficacy study of chloroquine (25mg/Kg/three days) was carried out in patients aged over 5 years old who were followed up for 28 days. Blood levels of chloroquine and, desethylchloroquine were measured on day two and on the day of reappearance of parasitemia. The cumulative incidence of treatment failure was calculated using the Kaplan & Meier survival analysis. Results. We studied 223 patients (Riberalta, 84; Guayaramerín, 80; Yacuiba, 59). The mean parasitemias (asexual) on day 0 were in Riberalta 6,147, Guayaramerín 4,251 and Yacuiba 5,214 parasites/ul of blood. In the same order, the average blood concentrations of chloroquine-desethylchloroquine during day 2 were 783, 817 and 815 ng/ml. No treatment failures were observed In Yacuiba, while in Riberalta and Guayaramerín, the frequencies of treatment failures were 6.2% and 10%. Blood levels of chloroquine and desethylchloroquine in patients with treatment failure showed values below 70 ng/ml on the day of reappearance of parasitemia. Conclusion. Resistance of Plasmodium vivax to chloroquine was not demonstrated in the three studied regions of Bolivia. Further studies are required for blood concentration levels of chloroquine. Introducción. Determinar la eficacia de la cloroquina contra el Plasmodium vivax permite mejorar la capacidad de vigilancia de la resistencia a los antipalúdicos. Objetivo. Evaluar la eficacia terapéutica de la cloroquina como tratamiento de malaria no complicada por Plasmodium vivax en Riberalta, Guayaramerín y Yacuiba, Bolivia. Materiales y métodos. Estudio de eficacia in vivo con pacientes mayores de 5 a os, se suministró cloroquina (25mg/Kg/ en tres días), y se realizó seguimiento por 28 días, midiendo los niveles de cloroquina en sangre y desetilcloroquina, el día dos y el día de registro de reaparición de parasitemia. Para la evaluación de la incidencia acumulada de falla del tratamiento, se usó el análisis de sobrevida de Kaplan & Meier. Resultados. Se estudiaron 223 pacientes (Riberalta 84; Guayaramerín 80; Yacuiba 59). Las medias de densidad parasitaria (formas asexuadas) del día 0 en Riberalta fueron de 6.147, en Guayaramerín 4.251 y en Yacuiba 5.214 parásitos/μl de sangre. En el mismo orden, los