[Drug resistance of Plasmodium falciparum in Congo. I. In vivo study with 10 and 25 mg/kg of chloroquine (235 tests)].

An evaluation of chloroquine resistance in P. falciparum was conducted in four different areas of the People's Republic of the Congo during the months of October and November 1985. Using the simplified seven day in vivo test protocol, 235 tests were completed in 92 children aged three months to five years seen at the Maternal Child Health Clinics (54 children were treated by a single dose at 10 mg/kg and 38 children were treated by the three day dose of 25 mg/kg) and 143 school children aged six to 12 years (70 treated by 10 mg/kg and 73 treated by 25 mg/kg). In three of the zones (Brazzaville, the forest mountains of the Mayombe and Chaillu), a high level of resistance was found in the percentage of children with asexual forms of P. falciparum parasites (1 000 leucocytes) in the blood smears. After 7 days, the percentage of positive results in children treated by 10 mg/kg was found to be 65.5% and 29.3% for children treated by 25 mg/kg. Failure rates, independent of parasite density, were less in school aged children. A significant number of observations seems to be Type II resistance. The situation is more favorable in the fourth area of Likouala, a region of flooded forests in the north of the country.