Drug sensitivity of Plasmodium falciparum in vivo and in vitro in Brazzaville (Congo)

Various projects were launched in 1993 to monitor the chemosensitivity of Plasmodium falciparum in Congo. Resistance of 34 strains in Brazzaville to chloroquine, quinine and mefloquine and of 35 to halofantrine was investigated in an in vitro survey using an isotopic micro test. The resistance rates were 61.8, 14.7, 3.0 and 0.0% respectively. Thus, the chemoresistance which first appeared in 1990 is confirmed and is stable in the population. This finding was further confirmed by a parallel in vitro analysis of sensitivity to chloroquine in Brazzaville. A chloroquine monitoring network is now being established throughout the country based on simplified WHO tests of 100 asymptomatic schoolchildren conducted every six months. The first results in 1993, from three Southern regions indicate that parasites are found in 20 to 60% of cases seven days after a standard 3 day treatment with 25 mg/kg, according to the region. The results of in vitro and in vivo tests are very variable. Indeed, the value of such results for these tests for national monitoring is questionable: a more reliable system of identifying true therapeutic failures would be better suited.