Chloroquine chemoprophylaxis in children during peak transmission period in Ethiopia.

A randomized controlled trial of the effect of chloroquine prophylaxis versus placebo on the occurrence of clinical malaria was carried out in 1988 among children aged 1-14 in the Awash Rift Valley of central Ethiopia. At the time of the study, chloroquine resistance had not been reported from this area. Two thousand children were randomly allocated to either chloroquine phosphate (5 mg base kg-1) or a multivitamin tablet. Treatment and weekly follow-up were carried out for 10 weeks during the peak malaria transmission season. There was no difference between chloroquine and placebo groups in the occurrence of at least one episode of clinical malaria, in smear positivity in those who remained free of attacks until the end of the study period, or in the prevalence of splenomegaly at the end of the study period. It is concluded that chloroquine prophylaxis is ineffective in preventing at least one clinical attack of malaria in children in this area.