Resistance of Plasmodium falciparum malaria to sulfadoxine-pyrimethamine ('Fansidar') in a refugee camp in Thailand.

Since it was first introduced 'Fansidar' (pyrimethamine 25 mg, sulfadoxine 500 mg) has been the preferred treatment for uncomplicated chloroquine-resistant Plasmodium falciparum malaria in Thailand. Because many patients at a refugee camp in Thailand did not seem to be responding to therapy 9 patients who received fansidar for P. falciparum infection were followed up with serial parasite counts. In all of them the infection was resistant to fansidar. The results of this study suggest that fansidar resistance is prevalent at this camp and should prompt more exhaustive studies of the epidemiology of fansidar resistance in the area.