Therapeutic efficacies of antimalarial drugs in the treatment of uncomplicated, Plasmodium falciparum malaria in Assam, north-eastern India.

In the Indian state of Assam, the current therapeutic efficacies of the drugs commonly used in the area for the treatment of uncomplicated, Plasmodium falciparum malaria were investigated. As is routine in this area, subjects found positive for P. falciparum malaria were initially treated with chloroquine (CQ). They were given sulfadoxine-pyrimethamine (SP) if this treatment failed, and subsequently quinine if the SP failed. The protocol of the World Health Organization's extended in-vivo test was used to follow parasite clearance and clinical cure. Therapeutic response was assessed by comparing the baseline (day-0) level of parasitaemia with that observed on day 3. Many (75.7%) of the 144 evaluable subjects were treatment successes after CQ, but six early (4.2%) and 29 (20.1%) late CQ-treatment failures were observed. Of the 34 CQ-treatment failures followed, 31 (91.2%) responded adequately to SP but the other three were early (one) or late (two) SP-treatment failures. Two (66.7%) of the SP-treatment failures responded adequately to parenteral quinine but the other (a late quinine-treatment failure) had to be given an artemisinin derivative to achieve a clinical cure. The foci in which multidrug-resistant cases of malaria are developing in India need to be identified quickly, so that such cases can be cured before the mutant strains of P. falciparum that are resistant to several drugs have a chance to become more widespread.