Efficacy of sulfadoxine/pyrimethamine in the treatment of uncomplicated Plasmodium falciparum malaria in Republic of Congo.

Congo is facing frequent failures of treatment of Plasmodium falciparum malaria with chloroquine (CQ), which is still recommended and used as a first-line drug. In Pointe-Noire and Brazzaville, the two largest cities that contain approximately 60% of the population of Congo, we compared the efficacy of CQ versus sulfadoxine/pyrimethamine (SP) for treatment of uncomplicated malaria in children 6-59 months old (mean = 33 months) using the standard World Health Organization (WHO) 14-day in vivo test in two phases between 1999 and 2002. Patients enrolled were randomly assigned to receive SP (25 mg/kg of sulfadoxine and 1.25 mg/kg of pyrimethamine) or CQ (25 mg/kg). In the first phase of the study, 46 patients were assigned to the CQ (n = 23) or SP (n = 23) groups in Pointe-Noire and 52 children were assigned to the CQ (n = 26) or to SP (n = 26) groups in Brazzaville. Results were interpreted according to the WHO lot quality assurance sampling method, and treatment failure rates for SP versus CQ were < 25% versus > 25% in both cities. In the second phase of the study, we accurately determined the actual proportion of treatment failures for SP in Brazzaville. Thus, in 75 of the 80 children enrolled and followed-up until day 14, no clinical or parasitologic failure was recorded and no serious adverse reaction was observed. Since the CQ treatment failure rate exceeds the unacceptable upper limit, SP seems well to be an appropriate alternative for the first-line treatment of uncomplicated P. falciparum malaria, at least in the settings of the present study.

Epidemiology of drug-resistant malaria in Republic of Congo: using molecular evidence for monitoring antimalarial drug resistance combined with assessment of antimalarial drug use.

In Congo, urgent efforts are needed to help with the revision of the national antimalarial drug policy. Despite its high resistance level, chloroquine (CQ) is still extensively used as the first-line treatment for uncomplicated Plasmodium falciparum malaria. The study was conducted in children under 5 years with uncomplicated malaria in Pointe-Noire and Brazzaville, the two largest cities that contain approximately 60% of the population of Congo. We investigated by polymerized chain reaction and sequencing methods the frequency distribution of molecular markers for antimalarial drug resistance, including mutations in P. falciparum chloroquine resistance transporter (pfcrt) gene associated with CQ resistance and mutations in dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes conferring resistance to sulphadoxine/pyrimethamine (SP) among pre-treatment P. falciparum isolates, as well as assessing antimalarial drug use in the community. pfcrt (K76T) mutation was present in most isolates (96.4%, n = 138) and high frequency (69.2%, n = 133) of triple-mutant dhfr-S108N, N51I, C59R was observed. The quintuple mutant (dhfr-S108N, N51I, C59R and dhps-A437G or S436A, K540E) considered as molecular marker for SP treatment failure was not found because dhps-K540E mutation was absent in isolates tested; this is a clear evidence for the excellent efficacy of SP that we previously described in the same population. The complete absence of the dhps-K540E mutation is a deterrent component for using this molecular marker as an early warning tool for SP resistance testing in that population. Poor compliance issues related to the antimalarial drug use including inappropriate manufacturing practices reported in this study require intensive attention and should be taken into account when implementing drug policy change. If Congo changes its treatment policy from CQ to SP monotherapy, this will not last long. The strategy of combining SP with other affordable and effective antimalarial drugs such as the artemisinin derivatives to improve efficacy and to delay the development of parasite resistance is essential.