Chloroquine-resistant Plasmodium falciparum malaria in Vanuatu.

Cases of malaria caused by Plasmodium falciparum resistant to chloroquine treatment have been probably occurring in Vanuatu for many years. In this survey, seven patients with P. falciparum malaria were investigated for evidence of resistance to chloroquine. In-vitro resistance to chloroquine was demonstrated in four. Two further patients who had clinical resistance to chloroquine treatment developed cerebral malaria. It is of interest that one of these patients was subsequently successfully treated with mepacrine. Two additional cases are cited as examples of resistance to chloroquine treatment encountered in the past.