High frequency of Plasmodium falciparum CICNI/SGEAA and CVIET haplotypes without association with resistance to sulfadoxine/pyrimethamine and chloroquine combination in the Daraweesh area, in Sudan.

Estimation of the prevalence of the molecular markers of sulfadoxine/pyrimethamine (SP) and chloroquine (CQ) resistance and validation of the association of mutations with resistance in different settings is needed for local policy guidance and for contributing to a global map for anti-malarial drug resistance. In this study, malaria patients treated with SP alone (60) and SP with CQ (194) had a total treatment failure (TF) of 35.4%, with no difference between the two arms. The polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA) method was used to identify polymorphisms in 15 loci in the dhfr, dhps and pfcrt genes in a subset of 168 infections. The results revealed a similar frequency of all single nucleotide polymorphisms (SNPs) in the two arms, except dhps 581G, which was over-represented in infections that failed to respond to SP alone (TF). In all infections, a high frequency of dhfr CICNI haplotype (51I and 108N) was found, but without discrimination between the adequate clinical and parasitological response (ACPR, 75.6%) and TF (82.9%). Similarly, the dhps SGEAA haplotype (437G and 540E) (ACPR, 60.5%; TF, 65.9%) and the combined CICNI/SGEAA haplotype (ACPR, 50%; TF 55%) were not associated with TF. In contrast to other studies in Africa, the triple 51I/59R/108N mutation was rare (0.6%). In addition, the pfcrt CVIET haplotype (93%) was found to be associated with the CICNI/SGEAA haplotype. Finally, these data represent a baseline for SP resistance molecular markers needed before the deployment of SP/artesunate combination therapy in the Sudan.

Efficacies of artesunate plus either sulfadoxine-pyrimethamine or amodiaquine, for the treatment of uncomplicated, Plasmodium falciparum malaria in eastern Sudan.

Artemisinin-based combination therapy (ACT) is increasingly being adopted as the first-line treatment for malaria in sub-Saharan Africa. In September-November 2005, in New Halfa, eastern Sudan, the efficacy of artesunate-sulfadoxine-pyrimethamine (AS-SP) for the treatment of uncomplicated, Plasmodium falciparum was compared with that of artesunate-amodiaquine (AS-AQ). The artesunate was given at 4 mg/kg. day on days 0-2, with either a single dose of SP (25 mg sulfadoxine/kg) given on day 0, or AQ, at 10 mg/kg. day, given on days 0-2. Eighty-two of the patients treated (40 given AS-SP and 42 given AS-AQ) completed the 28 days of follow-up. On day 3 all the patients were afebrile and only one patient, in the AS-AQ group, was still parasitaemic. AS-SP appeared slightly more efficacious than AS-AQ but the differences were not statistically significant. Only one patient (2.5%) given AS-SP but four (9.5%) of those given AS-AQ were initially considered to be late treatment and parasitological failures, with all other patients showing an adequate treatment response. The PCR-corrected frequencies of cure were 97.5% for AS-SP and 95.2% for AS-AQ (P>0.05). No gametocytaemias were observed during the follow-up and, although mild adverse effects (nausea, vomiting, abdominal pain, dizziness and/or rash) were detected in 14 patients, they occurred at the same frequency in each treatment arm. It therefore appears that the AS-SP and AS-AQ combinations were both effective and safe for the treatment of uncomplicated, P. falciparum malaria in eastern Sudan.

The roles of the pfcrt 76T and pfmdr1 86Y mutations, immunity and the initial level of parasitaemia, in predicting the outcome of chloroquine treatment in two areas with different transmission intensities.

The resistance of Plasmodium falciparum to chloroquine (CQ) is probably mediated by point mutations in two genes: pfcrt and pfmdr1. The aim of the present study was to investigate, in patients treated with CQ, the association between host factors, such as immunity and initial level of parasitaemia, and the ability to clear P. falciparum parasites carrying the key chloroquine-resistance (CQR) mutations, pfcrt 76T and pfmdr1 86Y. Identical CQ-efficacy trials were performed in 51 young children (aged <5 years) from Kibaha, in north-western Tanzania, and 44 patients (aged 3-57 years) from Darawish, in eastern Sudan. In both areas, all the CQ-treatment failures had infections with the 76T and 86Y alleles before treatment. Although the presence of these two alleles was significantly associated with treatment failure in Sudan (P=0.001), the corresponding association in Tanzania did not reach statistical significance (P=0.1). Of the 39 patients from Darawish and 44 from Kibaha who harboured parasites with the CQR mutations, 12 and 19, respectively, managed to clear their parasitaemias. The ability to clear CQR parasites was significantly associated with the initial level of parasitaemia (with P-values of 0.05 in Tanzania and 0.01 in Sudan) and with age-- the best surrogate for protective immunity in endemic areas (with P-values of 0.02 in Tanzania and 0.001 in Sudan). These results confirm previous observations that indicated that the 76T and 86Y alleles play a role in the mechanism of CQR, although other factors, such as level of parasitaemia when treated and age, are also important. The 76T and 86Y alleles could still be used as predictive markers for CQR, in non-immune individuals and low-transmission areas.