Chloroquine resistance in Plasmodium falciparum in Natal

Out of 110 cultures of Plasmodium falciparum obtained from infected patients in Natal 18 were found to be resistant to chloroquine by in vitro tests: 2 cultures showed schizont development in wells containing 24 pmol chloroquine; in 16 schizont development was present in culture wells containing 48 pmol chloroquine. Seventy-two patients with P. falciparum malaria who apparently did not respond to adequate oral chloroquine therapy were investigated. All responded to one or more treatments with pyrimethamine/sulphadoxine (Fansidar; Roche). It would seem that all the patients were infected in areas not controlled by the South African health authorities.