Chloroquine-resistant falciparum malaria in an area of rising endemicity in Zimbabwe.

Response of Plasmodium falciparum to chloroquine treatment was assessed in vivo in 219 malaria cases from eight villages in a formerly hypoendemic area of Zimbabwe experiencing a malaria outbreak. Seven (3%) of the cases were fully sensitive to chloroquine while 182 (83%) exhibited chloroquine-resistant responses. Of the 182 chloroquine-resistant cases 74 (41%) showed RI resistance while 108 (59%) exhibited RII-RIII resistance. In-vivo follow-up was not completed to Day 28 in the remaining 30 (14%) of the malaria cases, which were therefore either fully sensitive or RI resistant. In 23 (11%) of the malaria cases pyrexia and increasing parasitaemia occurred between Day 3 and Day 7 after treatment. Mean parasite clearance time was 5.8 days (s.d. 2.89 days) in patients who were cleared of asexual parasitaemia. In all but 1 (0.5%) of the chloroquine-resistant infections, asexual parasites were cleared by Day 7 following treatment with the sulphadoxine/pyrimethamine combination (Fansidar). This study showed an acute problem of chloroquine resistance in an area of Zimbabwe. It is recommended that the drug policy be modified to allow distribution of limited stocks of Fansidar to the local clinics for restricted use on documented chloroquine treatment failures within 7 days.