Prevalence of Dihydrofolate Reductase Gene Mutations in Plasmodium falciparum Isolate from Pregnant Women in Nigeria

Abstract

We assessed the prevalence of Plasmodium falciparum and the frequency of the dhfr triple mutation that is associated with antifolate drug resistance among P. falciparum isolates obtained from pregnant women in Ilorin, Nigeria. The study included 179 women in the second and third trimester of pregnancy who have been exposed to intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine. Thick and thin blood films and PCR were used for malaria parasite detection. Blood group and hemoglobin concentration were also determined. Mutations in P. falciparum dhfr were analyzed by sequencing DNA obtained from blood spots on filter paper. Prevalence of P. falciparum in the population (PCR corrected) was 44.1% (79/179) with 66.7% and 33.3% in the second and third trimester, respectively. Primigravide (51.3%) were more infected than multigravide (48.7%) but the difference was not statistically significant. Women in blood group A had the highest P. falciparum malaria infection (30.8%). The mean hemoglobin concentration was lower among those infected with malaria parasite. Also, more women with the malaria parasite (38.4%) had anemia compare to those without (21.4%). The prevalence of the P. falciparum dhfr mutant alleles was 64.1%, 61.5%, 38.5%, and 12.8% for I51, R59, N108 and T108, respectively. None of the samples had the L164 mutation. The combined triple dhfr mutation (51 + 59 + 108) in the population was 17.9% (7 of 39). Also, the prevalence of the triple mutant alleles was not significantly associated to the number of doses of SP taken by the women. These findings highlight the need for a regular assessment of IPTp/SP efficacy, and evaluation of possible alternative drugs.

Carriage of Mutant Dihydrofolate Reductase and Dihydropteroate Synthase Genes among <b><i>Plasmodium falciparum</i></b> Isolates Recovered from Pregnant Women with Asymptomatic Infection in Lagos, Nigeria

“…This study also supports the replacement of SP with the artemisinin combination therapy for treating uncomplicated malaria in children and adults proposed in 2005 despite the lack of molecular evidence at the time of the policy change [ 8 , 9 ]. However, in spite of reduced SP pressure, findings from this study have further confirmed the circulation of P. falciparum with SP resistance in Lagos with the implication of the SP pressure in the study area being higher than that of Lafia among the pregnant women population [ 15 ]. Generally, the higher prevalence rate of the 108N mutation is not surprising, since this mutation has been established by previous studies as the first to be selected in dhfr following exposure to pyrimethamine ex vivo to cause low-level resistance to pyrimethamine [ 12 , 13 ].…”

“…With regard to the presence of SP resistance in the study area, the present study revealed prevalence rates of 70, 75 and 80% for single mutations at codons 51, 59 and 108 in the homozygous or heterozygous forms that resulted in a 50% prevalence rate of triple dhfr mutant parasites circulating in the study area. These molecular indices are higher than the 64.1, 61.5, 38.5 and 17.5% reported by Ojurongbe et al [ 15 ] for P. falciparum among ASM pregnant women in Lafia, North-Central Nigeria. But they are lower than the 84–91% for 51I, 88 versus 87% for 59R and 95–97% for 108N reported by the same group among the P. falciparum population recovered from children with uncomplicated malaria in Osogbo, South-West Nigeria [ 14 , 15 ].…”

“…These molecular indices are higher than the 64.1, 61.5, 38.5 and 17.5% reported by Ojurongbe et al [ 15 ] for P. falciparum among ASM pregnant women in Lafia, North-Central Nigeria. But they are lower than the 84–91% for 51I, 88 versus 87% for 59R and 95–97% for 108N reported by the same group among the P. falciparum population recovered from children with uncomplicated malaria in Osogbo, South-West Nigeria [ 14 , 15 ]. This difference could be attributed to a variation in the level of use of SP and sulpha-related drugs such as pyrimethamine and cotrimoxazole in the country [ 9 , 11 ].…”

“…Unlike in other West African countries, studies monitoring the effectiveness of SP in the context of IPTp using the molecular surveillance approach have been grossly limited in Nigeria. Only two studies in 2010 and 2011 have documented the prevalence of SP resistance mutations in the country [ 14 , 15 ]. However, both studies investigated mutations in the pfdhfr gene only in children of <5 years and in pregnant women who had received IPTp.…”

Malaria: Control, Elimination, and Eradication

“…34 IPTp-SP is effective at preventing maternal anemia and low birth weight in areas where P. falciparum is susceptible to SP, 35,36 but the success of the intervention is threatened in many communities in Africa where resistance of P. falciparum to SP has been reported. 37,38 Following the WHO guideline for the treatment of uncomplicated malaria, ACTs were adopted in all malaria-endemic areas where resistance has been reported to chloroquine and other antimalarials. Adoption of ACTs reportedly led to a large reduction in confirmed malaria cases and contributed to the reduction in all mortality among children younger than 5 years of age.…”