Falciparum malaria resistant to chloroquine and Fansidar: Implications for prophylaxis

Abstract

Chloroquine resistant strains of Plasmodium falciparum have become established in east Africa since the first fully substantiated report of their existence in 1979. As a result Fansidar (pyrimethamine 25 mg and sulfadoxine 500 mg) has been recommended as routine antimalarial prophylaxis for this area. During the past year there have been several reports of falciparum malaria occurring in people taking Fansidar prophylaxis in east Africa together with reports of possible combined Fansidar and chloroquine resistance. We present a case of falciparum malaria resistant to both Fansidar and chloroquine with measurement of serum concentration of antimalarial agents before and during treatment and of in vitro chloroquine sensitivity. In our opinion the most logical recommendation for antimalarial prophylaxis in non-immune persons in east Africa at the moment is chloroquine 300 mg twice weekly, since this should provide a safe and effective defence against RI chloroquine resistant strains of P. falciparum. Until more is known about the determinants of toxicity this regimen should probably be followed for no more than one year. If, as seems likely, high level chloroquine resistance becomes established than Fansidar once weekly should be taken in addition to twice weekly chloroquine.