Efficacy of sulfadoxine-pyrimethamine, amodiaquine, and sulfadoxine-pyrimethamine–amodiaquine combination for the treatment of uncomplicated falciparum malaria in the urban and suburban areas of Brazzaville (Congo)

Congo-Brazzaville has recently adopted artesunate-amodiaquine as the first-line antimalarial drug to replace chloroquine. Before the implementation of this new strategy, we conducted several clinical studies to assess the therapeutic efficacy of former, classical first-line antimalarial drugs in the city of Brazzaville, in which reside about 30% of the Congolese population. From 2003 to 2005, non-randomised trials were conducted to evaluate the efficacy of sulfadoxine-pyrimethamine (SP) (n = 97 patients), amodiaquine (AQ) (n = 62 patients), and the combination of sulfadoxine-pyrimethamine–amodiaquine (n = 54 patients) in children aged between 6 months and 5 years with uncomplicated malaria using the 2003 WHO guidelines during the 28-day follow-up period. After excluding new infections by PCR, the proportion of treatment failure on day 28 was 30.2% (95% confidence interval, 19.2–43.0%) for sulfadoxine-pyrimethamine, 34.8% (95% confidence interval, 21.4–50.2%) for amodiaquine, and 14.2% (95% confidence interval, 5.9–27.2%) for sulfadoxine-pyrimethamine + amodiaquine combination. Treatment with sulfadoxine-pyrimethamine was associated with an increase of gametocyte charge. These results suggest that neither sulfadoxine-pyrimethamine nor amodiaquine is efficacious as monotherapy and that their combination may not remain effective in the coming years. Based on our results, the implementation of artemisinin-based combination therapy appears to be urgent in the country.