Combination Therapy In Plasmodium Falciparum Malaria In Sudan And Characterization Of Molecular Markers Of Chloroquine And Sulfadoxine-Pyrimethamine Resistance

Abstract

This work aimed at contributing data to help policy makers in planning malaria control and adopt policies that might delay the emergence of drug resistance in Sudan. A study conducted in a rural area, Gedaref State, eastern Sudan, has examined therapeutic efficacies of chloroquine (CQ) Plus dihydroartemisinin (DHA) and CQ plus sulfadoxinepyrimethamine (SP) in uncomplicated falciparum malaria. Plasmodium falciparum isolates of this area were genotyped for detection of mutations in P. falciparum chloroquine transporter (Pfcrt), multidrug resistance (Pfmdr1), dihydrofolate reductase (Pfdhfr) and dihydropteroate synthetase (Pfdhps) genes. Polymerase chain reaction (PCR) corrected cure rate was comparable in the two treatment arms (CQ + SP, 62.5% [15/24]; CQ + DHA, 68.2% [15/22]). The frequency of mutant alleles, Pfdhfr 51I, Pfdhfr 108N, Pfdhps 540E, Pfdhps 581G and Pfcrt 76T, Pfmdr1 86Y were; 0.84, 0.84, 0.80 and 0.20, 0.90, 0.86, respectively. No mutations were detected in positions A16V, C59R and I164L, and for Pfdhps loci S436A, A437G and A613S. There was statistically significant association between Pfcrt 76T and Pfmdr1 86Y alleles associated with CQ resistance (P ≤ 0.001), and between Pfdhfr 51I, Pfdhfr 108N and Pfdhps 540E alleles associated with SP resistance (P ≤ 0.001–0.04) and all the detected mutations in both CQ and SP resistance genes (P = 0.001) except Pfdhps 581G. Another study in suburban area in Khartoum State has examined therapeutic efficacy of SP plus artesunate (AS) in treatment of uncomplicated falciparum malaria. Furthermore, polymorphisms associated with SP resistance in Pfdhfr and Pfdhps genes were examined. PCR corrected cure rate was 92.6%. Single nucleotide polymorphisms (SNP) were detected in positions 51 and 108 Pfdhfr, and positions 436/437, 540 and 581 of Pfdhps. The most frequent haplotype was Pfdhfr double mutant haplotype CICNI detected in 91.9% (N = 79) of the infections, only one infection (1.2%) expressed the wild type Pfdhfr haplotype (CNCSI). In contrast Pfdhps mutant haplotypes were found at low rate (9.6%), and only two infections (2.2%) had more than one mutation. No significant association was observed between the presence of Pfdhfr and/or Pfdhps mutant haplotypes and SP plus AS treatment failure. VIII A study in New Halfa and Kassala, eastern Sudan has investigated the distribution of Pfdhfr, Pfdhps SP resistance determinant haplotypes. Quintuple mutations at Pfdhfr 51/59/108 and Pfdhps 437/540 positions were detected for the first time in Sudan (2.9% in New Halfa and 5.9% in Kassala). In both study sites the predominant Pfdhfr mutant haplotype was the double mutant haplotype (CICNI). Plasmodium falciparum dhfr triple mutant haplotype (CIRNI) was identified in New Halfa (2.5%) and Kassala (4.1%). Plasmodium falciparum dhps haplotype; harboring 437G and 540E mutations was the most frequent mutant Pfdhps haplotype in both sites yielding a percentage of 17.7 in New Halfa and 62.5 in Kassala. Failure to AS plus SP, high frequency of SP resistance marker alleles in different parts of the country, in addition to the presence of quintuple mutations in Pfdhfr/Pfdhps genes is alarming.