[Evolution of Plasmodium falciparum drug sensitivity in Madagascar from 1982 to 1993 and operational consequences]

Madagascar was one of the first African countries with reported chloroquine drug resistance of P. falciparum. Suspected as early as 1975, it was confirmed in 1981. Hereafter, regular tests in vivo and in vitro have been performed and allow for a study of drug resistance development. In 742 standard in vivo tests at the dose of 25 mg/kg of chloroquine that were executed between 1983 and 1993, R I resistance levels could be found in 8.5% of cases, R II was found in 8.2%. No resistance at R III levels was detected. The overall situation for in vitro is equally favorable. In 406 tests 78% of samples proved sensitive. The investigations undertaken by the Pasteur Institute of Madagascar, by the Institute for Tropical Medicine and Epidemiology in Paris and by the Unit of Epidemiological Surveillance within the Malagasy Ministry of Health raise a number of questions: Taking to account the various causes for imprecision in measurement and in evaluation (variations in parasite density, microscopic detection levels, bio-availability of the drug) of the groups of R I and R II how significant are the variations observed in numbers and proportions of resistance levels R I and R II? How important are the effects of auto-medication? Can they be correctly evaluated by Bergquist's test? How explain the low level of drug resistance in a country close to East Africa, in which chemoprophylaxis has been widely practiced and in which insufficient dosage for treatment is common? The absence of R III resistance in vivo permit for chloroquine to remain the first line treatment for malaria in Madagascar.(ABSTRACT TRUNCATED AT 250 WORDS)