Prevalence of Plasmodium falciparum Resistance Markers to Sulfadoxine-Pyrimethamine among Pregnant Women Receiving Intermittent Preventive Treatment for Malaria in Uganda

Abstract

The aim of this study was to assess the prevalence of mutations in Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes among pregnant women using sulfadoxine-pyrimethamine (SP) as an intermittent preventive treatment (IPTp). A molecular epidemiological study of P. falciparum parasite resistance markers to SP was conducted from August 2010 to February 2012 in Mukono district in central Uganda. DNA was extracted from 413 P. falciparum-positive samples. Real-time PCR, followed by melting curve analysis, was used to characterize point mutations in the Pfdhfr and Pfdhps genes that are associated with SP resistance. The prevalence of the single-nucleotide mutations in Pfdhfr at codons 51I, 59R, and 108N and in Pfdhps at codons 437G and 540E was high (>98%), reaching 100% fixation after one dose of SP, while the prevalence of 581G was 3.3% at baseline, reaching 12.5% after one dose of SP. At baseline, the prevalence of Pfdhfr and Pfdhps quintuple mutations was 89%, whereas the sextuple mutations (including 581G) were not prevalent (3.9%), reaching 16.7% after one dose of SP. However, the numbers of infections at follow-up visits were small, and hence there was insufficient statistical power to test whether there was a true rise in the prevalence of this allele. The overall high frequency of Pfdhfr and Pfdhps quintuple mutations throughout pregnancy excluded further analyses of possible associations between certain haplotypes and the risk of lower birth weight and anemia. However, women infected with P. falciparum had 1.3-g/dl-lower hemoglobin levels (P ‫؍‬ 0.001) and delivered babies with a 400-g-lower birth weight (P ‫؍‬ 0.001) compared to nonparasitemic women. Despite this, 44 women who were P. falciparum positive at baseline became negative after one or two doses of SP (i.e., 50.5%), implying that SP-IPTp still has some efficacy. P. falciparum resistance markers to SP are high in this population, whereas P. falciparum infection was associated with poor birth outcomes. Malaria in pregnancy is a major public health problem in areas where malaria is endemic (1, 2). The current policy in Uganda for treating malaria in pregnancy in the first trimester is to give quinine (10 mg/kg). During the second and third trimesters, the following artemesinin-based combination therapy is recommended: Coartem (artemether [20 mg] and lumefantrine [120 mg]) at four tablets twice a day for 3 days. For malaria prevention, the policy recommendation is at least two doses of sulfadoxinepyrimethamine (SP) as an intermittent preventive treatment of malaria in pregnancy (IPTp) (3). Recently, the World Health Organization (WHO) issued new guidelines on IPTp for countries in areas of moderate to high transmission: IPTp with SP is now recommended for all pregnant women at each scheduled antenatal care (ANC) visit, and each SP dose should be given at least monthly (4). This recommendation is based on evidence that three or more doses of SP as IPTp are more beneficial in reducing the risk of low-birth-w...

Burden of Placental Malaria among Pregnant Women Who Use or Do Not Use Intermittent Preventive Treatment at Mulago Hospital, Kampala

“…This finding suggests that SP may still be beneficial in preventing placental malaria and its associated adverse outcomes. This finding is consistent with clinical outcomes from several recent studies that assessed the efficacy of SP-IPTp in settings with a high prevalence of SP resistance mutations [13, 23, 24, 26–28]. SP-IPTp works by the clearance of asymptomatic parasitemia followed by posttreatment prophylaxis (PTP) [38].…”

“…While the prevalence of the dhfr/dhps quintuple mutations is generally high for Kampala (>80%), there are no reliable estimates for the prevalence of the Pfdhps A581G mutation. However, recent estimates from the neighbouring Mukono district placed the prevalence at 3.9% among pregnant women presenting for ANC [13]. …”

“…Whereas these interventions have targeted the population at large, intermittent preventive treatment with sulfadoxine-pyrimethamine (SP-IPTp) has been particularly implemented as an additional measure to prevent MIP [12]. Yet, recent times have seen increasing concerns about the effectiveness of SP-IPTp both locally [13–15] and globally [16–18]. These concerns have been largely driven by the rising prevalence of higher-level SP resistance mutations.…”

“…Because unsupervised SP-IPTp administration is a common occurrence in many resource-limited settings, we have previously argued that self-reports and ANC records may not necessarily translate into SP intake compliance [21, 22]. Moreover, where intake was ascertainable, studies have continued to show effectiveness of SP-IPTp [13, 23–29]. Consequently, some authors have questioned the usefulness of molecular markers in monitoring SP-IPTp effectiveness [25, 27, 30].…”

Dihydroartemisinin–Piperaquine for the Prevention of Malaria in Pregnancy

“…9,25-27 Observational studies from East Africa suggested that the use of sulfadoxine–pyrimethamine as intermittent preventive treatment during pregnancy provided minimal or no benefit, 10,12,13 and in a randomized trial involving young Ugandan children, intermittent preventive treatment with monthly sulfadoxine–pyrimethamine provided no protection against malaria. 28 A few controlled trials have evaluated alternatives to sulfadoxine–pyrimethamine, including amodiaquine and mefloquine, for intermittent preventive treatment during pregnancy; however, they have not shown convincing evidence of higher efficacy, and the drugs had a poor side-effect profile.…”