Abstract
BackgroundArtesunate/sulphadoxine-pyrimethamine (AS/SP) has been the first-line treatment for falciparum malaria in Sudan since 2004. The impact of this combination on anti-malarial resistance-associated molecular markers has not been investigated. In this study, an evaluation of the efficacy and prevalence of drug resistance alleles (pfcrt, pfmdr1, pfdhfr and pfdhps) eight years after the adoption of AS/SP in eastern Sudan is reported.MethodsA 28-day follow-up efficacy trial of AS/SP was conducted in eastern Sudan during the 2012 transmission season. Blood smears were collected from patients on days 0, 1, 2, 3, 7, 14, 21 and 28. Blood spots on filter paper were obtained pre-treatment and on the day the patient was parasite positive by microscopy. Genotyping of alleles was performed by qPCR (pfcrt 72–76 and pfmdr1 copy number) and direct sequencing of pfmdr1, pfdhfr and pfdhps.ResultsSixty-three patients out of 68 (93%) completed the 28-day follow-up, adequate clinical, and parasitological response occurred in 90.5% and 85.3% of the patients in the per-protocol and intent-to-treat analyses, respectively. PCR corrected per-protocol efficacy was 93.7%. The enrolment prevalence of pfcrt-CVMNK was 30.2% and pfmdr1-N86 was 40.3%. The pfmdr1 haplotype NFD occurred in 32.8% of pre-treatment samples and was significantly higher than previous reports (Fisher’s exact p = 0.0001). The pfdhfr-51I/108N combination occurred in all sequenced isolates and 59R was observed in a single individual. pfdhps substitutions 436A, 437G, 540E, 581G and 613S were observed at 7.8, 77.3, 76.9%, 33.8% and 0.0%, respectively. Treatment failures were associated with the pfdhps haplotype SGEGA at these five codons (OR 7.3; 95% CI 0.65 - 368; p = 0.048).ConclusionThe decrease of CQR associated genotypes reflects the formal policy of complete removal of CQ in Sudan. However, the frequency of markers associated with SP failure is increasing in this study area and may be contributing to the treatment efficacy falling below 90%. Further monitoring of AS/SP efficacy and of post-treatment selection of pfdhfr and pfdhps alleles in vivo is required to inform future treatment guidelines.
Highlights
Artesunate/sulphadoxine-pyrimethamine (AS/SP) has been the first-line treatment for falciparum malaria in Sudan since 2004
The in vivo efficacy of SP in eastern Sudan was reported at 82% [10], similar to Tanzania (86%) [11] and high levels of resistance to SP in East Africa [12,13] may render the short half-life artesunate partner unprotected
Patients enrolment Patients were recruited between January and March 2012 at Fatima Eldiaaig Health Centre in Kassala City in eastern Sudan, which is characterized by moderate perennial malaria transmission with a peak in January [45]
Summary
Artesunate/sulphadoxine-pyrimethamine (AS/SP) has been the first-line treatment for falciparum malaria in Sudan since 2004. The impact of this combination on anti-malarial resistance-associated molecular markers has not been investigated. Artesunate-sulphadoxine/pyrimethamine (AS/ SP) and artemether-lumefantrine (AL) became the firstand second-line of treatment, respectively, for uncomplicated P. falciparum malaria in 2004 [9]. The emergence of slow clearing parasites following artesunate treatment in South East Asia [14,15] has prompted closer monitoring of the efficacy of ACT and necessitated extensive research on molecular markers of resistance to artemisinins and partner drugs
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