Chemotherapy of falciparum malaria: regional differences in responsiveness to treatment.

A review of chloroquine and sulfa-antifol combination treated falciparum malaria patients revealed a high incidence of chloroquine-resistance, wither R1 or R2, in patients infected in Southeast Asia or Oceania. In addition, more than one tenth of the patients infected in Laos or Thailand were resistant to sulfa-antifol combinations. Chloroquine-resistant cases were sensitive to sulfa-antifol combinations. On the other hand, while all patients treated in Tokyo who had been infected in Africa or Sri Lanka were sensitive to chloroquine, a field study suggested the presence of chloroquine-resistant P. falciparum in the area near Kaduna, Nigeria. One patient infected in Nigeria showed partial resistance to the MP (sulfamonomethoxine-pyrimethamine) combination, and another patient infected in the Central African Empire showed resistance to the MP combination, increasing from R1 to R3 within a short period. The incidence of resistance to sulfa-antifol combination therapy was high in the West African tropical region. The continent, county and area of infection should be taken in consideration when selecting antimalarial drug(s) for the treatment and suppression of falciparum malaria.