Chloroquine efficacy study in Zambia

Reduction of morbidity and mortality is dependent on early diagnosis and adequate treatment, but the latter is increasingly hampered by what is suspected to be an emerging resistance of P. falciparum to chloroquine. In recognition of this problem, the Government of Zambia wishes to establish a sentinel surveillance system to better analyze the efficacy of chloroquine. In response to this need, and as a bridging activity to the USAID-supported Zambia Child Health Project, chloroquine efficacy studies were carried out in Chipata District, Eastern Province, from May to July, 1995, during which 558 children under age 5 were screened in two clinics. Children with measured fever and moderate parasitemia were enrolled in the study. Of the 70 children treated with chloroquine and adequately followed, 68.5% showed resistance at the RII or RIII level and 41.4% experienced either a clinical failure or needed to be treated with an alternative drug because of unacceptable parasite response to chloroquine. Of the 45 children treated with sulfadoxine-pyrimethamine, 6.7% showed RII response, but all were free of parasites and fever by the fourteenth day. Differences in response between the two clinics in Chipata District (one semi-rural and one urban) and between the response in Chipata and a neighboring district raise interesting scientific questions which should be addressed by further research. It is recommended that further development of the monitoring and malaria drug policy framework continue with USAID support and with the close collaboration of WHO and other donor partners. The very significant failure levels of treatment failure with chloroquine call for an urgent reassessment of treatment guidelines, particularly for Eastern Province. A detailed protocol for drug efficacy monitoring in Zambia is appended. Includes references.