Summary Since 1994, the Peruvian Malaria Control Program has used a simplified operational approach for monitoring antimalarial drug efficacy, in which blood smears are taken 7 and 14 days after treatment from all patients diagnosed with malaria at Ministry of Health facilities.
The proportion of patients with parasitaemia on one of their return visits provides an indication of the efficacy of the drug being administered. We compared this approach for antimalarial drug resistance monitoring to the more labour-intensive and expensive World Health Organization (WHO)
14-day in vivo efficacy trial at six sites in the Amazon Basin and the north coast of Peru. Although the proportion of treatment failures at 7 and 14 days identified by the operational monitoring system was considerably lower than the results of the WHO in vivo efficacy
test, the operational approach did accurately reflect the overall efficacy or lack of efficacy of the drugs being evaluated. Differences in the results of the two methods were greatest in the Peruvian Amazon region, where fully supervised treatment and patient follow-up is very difficult due
to the widely dispersed population. While the operational approach cannot be considered an alternative to WHO in vivo testing for evaluating the efficacy of antimalarial drugs or for recommending changes in malaria treatment policy, if treatment is supervised and follow-up blood smears
taken as scheduled, this method could serve as a simple, inexpensive and sustainable early warning system for reduced drug efficacy.