Sulphadoxine-pyrimethamine Resistance Research Articles

ONT sequencing identifies a high prevalence of crt sensitive, triple mutant dhfr and single mutant dhps parasites within an ANC population in Nigeria.

Malaria in pregnancy is a major public health issue, particularly among vulnerable populations in malaria-endemic sub-Saharan African countries. To mitigate its risks, WHO recommends sulphadoxine-pyrimethamine (SP) for chemoprevention and artemisinin-based combination therapy (ACT) to treat uncomplicated Plasmodium falciparum malaria. These interventions have helped to alleviate the risk associated with malaria in pregnancy; however, in the context of the emergence of SP- and ACT-resistant P. falciparum, maintained efficacy is under threat. Molecular surveillance is a reliable tool to monitor the emergence of resistance where molecular markers are known. Thus, the objective of the study was to use a multiplexed amplicon Oxford Nanopore sequencing approach to assess the molecular markers for antimalarial resistance among pregnant women in Nigeria. Dried blood spots (DBS) were collected from pregnant women who received IPTp-SP at the enrollment and follow-up visits. P. falciparum genomic DNA was extracted by the Chelex® method and Pf18S qPCR was used to detect parasite DNA in each sample. With nested PCR assays, fragments of Pfdhps, Pfdhfr, Pfmdr1, Pfcrt, Pfk13 and Pfama1 genes were amplified and multiplexed amplicon-based sequencing was conducted on the minION Oxford Nanopore Technology. In total, 251 pregnant women were enrolled in the study and 457 DBS samples were collected. P. falciparum genomic DNA was detected in 12% (56/457) of the samples, 31 at baseline and the remaining during the follow-up visits. Pfama1, pfk13, Pfdhps, Pfdhfr, Pfmdr1 and Pfcrt were successfully sequenced in a single run. Notably, k13 artemisinin resistance mutations were absent, the frequencies of Pfdhfr and Pfdhps SP resistance haplotypes, IRN for pyrimethamine resistance and ISGKA/IAGKA associated with sulphadoxine resistance were 82% (36/44) and 64% (27/42), respectively, and the Pfcrt CVIET resistant haplotype was at approximately 22% (7/32). Here a multiplexed amplicon-based ONT assay established that triple mutant Pfdfhr-IRN, double mutant Pfdhps-SG haplotypes and the chloroquine sensitive strain were prevalent among pregnant women in Nigeria.

Putative molecular markers of Plasmodium falciparum resistance to antimalarial drugs in malaria parasites from Ghana.

Antimalarial drugs including artemisinin-based combination therapy (ACT) regimens and sulphadoxine-pyrimethamine (SP) are used in Ghana for malaria therapeutics and prophylaxis respectively. The genetic basis of Plasmodium falciparum development of drug resistance involves single nucleotide polymorphisms in genes encoding proteins for multiple cellular and metabolic processes. The prevalence of single nucleotide polymorphisms in nine P. falciparum genes linked to ACT and SP resistance in the malaria parasite population was determined. Archived filter paper blood blot samples from patients aged 9 years and below with uncomplicated malaria reporting at 10 sentinel sites located in three ecological zones for the Malaria Therapeutic Efficacy Studies were used. The samples used were collected from 2007-2018 malaria transmission seasons and mutations in the genes were detected using PCR and Sanger sequencing. In all 1,142 samples were used for the study. For falcipain-2 gene (pffp2), Sanger sequencing was successful for 872 samples and were further analysed. The prevalence of the mutants was 45% (392/872) with pffp2 markers V51I and S59F occurring in 15.0% (128/872) and 3.0% (26/872) of the samples respectively. Prevalence of other P. falciparum gene mutations: coronin (pfcoronin) was 44.8% (37/90); cysteine desulfurase (pfnfs) was 73.9% (68/92); apicoplast ribosomal protein S10 (pfarps10) was 36.8% (35/95); ferredoxin (pffd) was 8.8% (8/91); multidrug resistance protein-1 (pfmrp1) was 95.2.0% (80/84); multidrug resistance protein-2 (pfmrp2) was 91.4% (32/35); dihydrofolate reductase (pfdhfr) was 99.0% (84/85); dihydropteroate synthase (pfdhps) was 72% (68/95). The observation of numerous mutations in these genes of interest in the Ghanaian isolates, some of which have been implicated in delayed parasite clearance is of great interest. The presence of these genotypes may account for the decline in the efficacies of ACT regimens being used to treat uncomplicated malaria in the country. The need for continuous monitoring of these genetic markers to give first-hand information on parasite susceptibility to antimalarial drugs to inform policy makers and stakeholders in malaria elimination in the country is further discussed.

Polymorphisms in Plasmodium falciparum dihydropteroate synthetase and dihydrofolate reductase genes in Nigerian children with uncomplicated malaria using high-resolution melting technique

In 2005, the Nigerian Federal Ministry of Health revised the treatment policy for uncomplicated malaria with the introduction of artemisinin-based combination therapies (ACTs). This policy change discouraged the use of Sulphadoxine-pyrimethamine (SP) as the second-line treatment of uncomplicated falciparum malaria. However, SP is used as an intermittent preventive treatment of malaria in pregnancy (IPTp) and seasonal malaria chemoprevention (SMC) in children aged 3–59 months. There have been increasing reports of SP resistance especially in the non-pregnant population in Nigeria, thus, the need to continually monitor the efficacy of SP as IPTp and SMC by estimating polymorphisms in dihydropteroate synthetase (dhps) and dihydrofolate reductase (dhfr) genes associated with SP resistance. The high resolution-melting (HRM) assay was used to investigate polymorphisms in codons 51, 59, 108 and 164 of the dhfr gene and codons 437, 540, 581 and 613 of the dhps gene. DNA was extracted from 271 dried bloodspot filter paper samples obtained from children (< 5 years old) with uncomplicated malaria. The dhfr triple mutant I51R59N108, dhps double mutant G437G581 and quadruple dhfr I51R59N108 + dhps G437 mutant haplotypes were observed in 80.8%, 13.7% and 52.8% parasites, respectively. Although the quintuple dhfr I51R59N108 + dhps G437E540 and sextuple dhfr I51R59N108 + dhps G437E540G581 mutant haplotypes linked with in-vivo and in-vitro SP resistance were not detected, constant surveillance of these haplotypes should be done in the country to detect any change in prevalence.

High Prevalence of Molecular Markers of Plasmodium falciparum Resistance to Sulphadoxine-Pyrimethamine in Parts of Ghana: A Threat to ITPTp-SP?

Malaria in pregnancy is a huge public health problem as it is the cause of maternal anaemia, still birth, premature delivery, low birth weight among others. To tackle this problem, WHO recommended the administration, during pregnancy, of intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP). The introduction of this policy is likely to create SP drug pressure which may lead to the emergence of parasite strains resistant to the drug. This study investigated the prevalence of the molecular markers of SP resistance as pointers to potential failure of IPTp-SP among pregnant women attending antenatal clinic, women at the point of baby delivery and out patients department (OPD) attendees. The study was conducted in health facilities located in parts of Ghana. Prevalence of mutations in dhfr and dhps genes of Plasmodium falciparum was determined using the method described by Duraisingh et al. The outcome of the study indicated the presence of high prevalence of strains of P.falciparum with the resistant alleles of the dhfr or dhps genes in the three categories of participants. There was a high prevalence of triple mutations (IRN) in the dhfr gene of P.falciparum isolates: 71.4% in peripheral blood of antenatal attendees; 74.1% in placenta cord blood of delivering mothers and 71.1% in OPD attendees. Quintuple mutations were only found in 2 (0.5%) isolates from OPD attendees. This observation might have occurred due to the increased use of SP for IPTp among others. There is the need for an interventional measure in order to protect pregnant women and their unborn children. Lay summaryWhen pregnant women get infected with the malaria parasites they are exposed to all manner of dangers including pre-term delivery, still birth, maternal anaemia and low birth weight. Taking sulphadoxine-pyrimethamine (SP) at predetermined periods during pregnancy, referred to as 'intermittent preventive treatment with SP' (IPTp-SP)' helps to curtail these problems. However, the frequent taking of these drugs is likely to create SP drug pressure which may lead to the emergence of parasite strains that are not readily killed by the drugs. In order to ascertain this phenomenon and advice stakeholders, this study determined the prevalence of certain 'materials' certified as markers of parasite resistance to SP. Alarmingly, more than 5% of all the category of women recruited to participate in this study were found to harbour the parasites that causes malaria. The outcome, also suggest the existence of high levels of strains of the malaria parasite, carrying the materials that make them to become resistant to SP. Policy makers must pay attention to these observations and institute measures to avoid escalation of the situation.

Surveillance of molecular markers of antimalarial drug resistance in Plasmodium falciparum and Plasmodium vivax in Federally Administered Tribal Area (FATA), Pakistan.

ABSTRACTThis molecular epidemiological study was designed to determine the antimalarial drug resistance pattern, and the genetic diversity of malaria isolates collected from a war-altered Federally Administered Tribal Area (FATA), in Pakistan. Clinical isolates were collected from Bajaur, Mohmand, Khyber, Orakzai and Kurram agencies of FATA region between May 2017 and May 2018, and they underwent DNA extraction and amplification. The investigation of gene polymorphisms in drug resistance genes (dhfr, dhps, crt, and mdr1) of Plasmodium falciparum and Plasmodium vivax was carried out by pyrosequencing and Sanger sequencing, respectively. Out of 679 PCR-confirmed malaria samples, 523 (77%) were P. vivax, 121 (18%) P. falciparum, and 35 (5%) had mixed-species infections. All P. falciparum isolates had pfdhfr double mutants (C59R+S108N), while pfdhfr/pfdhps triple mutants (C59R+S108N+A437G) were detected in 11.5% of the samples. About 97.4% of P. falciparum isolates contained pfcrt K76T mutation, while pfmdr1 N86Y and Y184F mutations were present in 18.2% and 10.2% of the samples. P. vivax pvdhfr S58R mutation was present in 24.9% of isolates and the S117N mutation in 36.2%, while no mutation in the pvdhps gene was found. Pvmdr1 F1076L mutation was found in nearly all samples, as it was observed in 98.9% of isolates. No significant anti-folate and chloroquine resistance was observed in P. vivax; however, mutations associated with antifolate-resistance were found, and the chloroquine-resistant gene has been observed in 100% of P. falciparum isolates. Chloroquine and sulphadoxine-pyrimethamine resistance were found to be high in P. falciparum and low in P. vivax. Chloroquine could still be used for P. vivax infection but need to be tested in vivo, whereas a replacement of the artemisinin combination therapy for P. falciparum appears to be justified.

Surveillance of molecular markers of antimalarial drug resistance in Plasmodium falciparum and Plasmodium vivax in Federally Administered Tribal Area (FATA), Pakistan

This molecular epidemiological study was designed to determine the antimalarial drug resistance pattern, and the genetic diversity of malaria isolates collected from a war-altered Federally Administered Tribal Area (FATA), in Pakistan. Clinical isolates were collected from Bajaur, Mohmand, Khyber, Orakzai and Kurram agencies of FATA region between May 2017 and May 2018, and they underwent DNA extraction and amplification. The investigation of gene polymorphisms in drug resistance genes (dhfr, dhps, crt, and mdr1) of Plasmodium falciparum and Plasmodium vivax was carried out by pyrosequencing and Sanger sequencing, respectively. Out of 679 PCR-confirmed malaria samples, 523 (77%) were P. vivax, 121 (18%) P. falciparum, and 35 (5%) had mixed-species infections. All P. falciparum isolates had pfdhfr double mutants (C59R+S108N), while pfdhfr/pfdhps triple mutants (C59R+S108N+A437G) were detected in 11.5% of the samples. About 97.4% of P. falciparum isolates contained pfcrt K76T mutation, while pfmdr1 N86Y and Y184F mutations were present in 18.2% and 10.2% of the samples. P. vivax pvdhfr S58R mutation was present in 24.9% of isolates and the S117N mutation in 36.2%, while no mutation in the pvdhps gene was found. Pvmdr1 F1076L mutation was found in nearly all samples, as it was observed in 98.9% of isolates. No significant anti-folate and chloroquine resistance was observed in P. vivax; however, mutations associated with antifolate-resistance were found, and the chloroquine-resistant gene has been observed in 100% of P. falciparum isolates. Chloroquine and sulphadoxine-pyrimethamine resistance were found to be high in P. falciparum and low in P. vivax. Chloroquine could still be used for P. vivax infection but need to be tested in vivo, whereas a replacement of the artemisinin combination therapy for P. falciparum appears to be justified.

High multiple mutations of Plasmodium falciparum-resistant genotypes to sulphadoxine-pyrimethamine in Lagos, Nigeria

BackgroundPlasmodium falciparum-resistance to sulphadoxine-pyrimethamine (SP) has been largely reported among pregnant women. However, the profile of resistance markers to SP dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) in the general population are varied and not frequently monitored. Currently, SP is used as partner drug for artemisinin combination therapy (SP-artesunate) in some sub-Saharan African countries or as a prophylactic drug in intermittent preventive treatment of malaria during pregnancy and infants and in seasonal malaria chemoprevention (SMC). Profiling of P. falciparum-resistant genotypes to SP is dynamic and critical in providing data that would be useful for malaria control programmes. This study assessed the profile of dhfr and dhps genes genotypes among individuals with malaria in Lagos, Nigeria.MethodsMolecular markers of SP resistance were identified by nested PCR and sequenced among malaria positive dried blood spots (DBS) that were collected from individuals attending health facilities from January 2013 to February 2014 and during community surveys from October 2010 to September 2011 across different Local Government Areas of Lagos State, Nigeria.ResultsA total of 242 and 167 samples were sequenced for dhfr and dhps, respectively. Sequence analysis of dhfr showed that 95.5% (231/242), 96.3% (233/242) and 96.7% (234/242) of the samples had N51I, C59R and S108N mutant alleles, respectively. The prevalence of dhps mutation at codons A437G, A613S, S436A, A581G, I431V and K540E were 95.8% (160/167), 41.9% (70/167), 41.3% (69/167), 31.1% (52/167), 25.1% (42/167), and 1.2% (2/167) respectively. The prevalence of triple mutations (CIRNI) in dhfr was 93.8% and 44.3% for the single dhps haplotype mutation (SGKAA). Partial SP-resistance due to quadruple dhfr-dhps haplotype mutations (CIRNI-SGKAA) and octuple haplotype mutations (CIRNI-VAGKGS) with rate of 42.6% and 22.0%, respectively has been reported.ConclusionsThere was increased prevalence in dhfr triple haplotype mutations when compared with previous reports in the same environment but aligned with high prevalence in other locations in Nigeria and other countries in Africa. Also, high prevalence of dhfr and dhps mutant alleles occurred in the study areas in Lagos, Nigeria five to eight years after the introduction of artemisinin combination therapy underscores the need for continuous monitoring.

Molecular detection of antimalarial drug resistance in Plasmodium vivax from returned travellers to NSW, Australia during 2008-2018.

To monitor drug resistance in Plasmodium vivax, a multidrug resistance 1 (Pvmdr1) gene and a putative transporter protein (Pvcrt-o) gene were used as molecular markers for chloroquine resistance. The biomarkers, the dihydrofolate reductase (Pvdhfr) gene and the dihydropteroate synthetase (Pvdhps) gene, were also used for the detection of resistance to sulphadoxine-pyrimethamine (SP); this drug is often accidentally used to treat P. vivax infections. Clinical blood samples (n = 120) were collected from patients who had been to one of eight malaria-endemic countries and diagnosed with P. vivax infection. The chloroquine resistance marker, the Pvmdr1 gene, showed F976:L1076 mutations and L1076 mutation. A K10 insertion in the Pvcrt-o gene was also found among the samples successfully sequenced. A combination of L/I57:R58:M61:T117 mutations in the Pvdhfr gene and G383:G553 mutations in the Pvdhps gene were also observed. Mutations found in these genes indicate that drug resistance is present in these eight countries. Whether or not countries are using chloroquine to treat P. vivax, there appears to be an increase in mutation numbers in resistance gene markers. The detected changes in mutation rates of these genes do suggest that there is still a trend towards increasing P. vivax resistance to chloroquine. The presence of the mutations associated with SP resistance indicates that P. vivax has had exposure to SP and this may be a consequence of either misdiagnosis or coinfections with P. falciparum in the past.

Frequency of Merozoite Surface Protein 2 (MSP2) Allelic Families and Sulphadoxine-Pyrimethamine (SP) Resistance Markers Among Pregnant Women in Delta State, Nigeria)

Malaria in pregnancy is a public health problem and requires prophylactic treatment with Sulphadoxine–Pyrimethamine (SP) drug. However, the emergence and spread of SP-resistance P. falciparum parasite across Nigeria poses serious threat to the efficacy and effectiveness of this preventive intervention. This study aimed to determine the frequency of MSP2 allelic families and SP resistance molecular markers of P. falciparum among asymptomatic pregnant women in Asaba, Delta State. Rapid Diagnostic Test (RDT) and Microscopy were used to detect malaria parasite infection among the study participants. Polymerase Chain Reaction (PCR) was used to confirm parasitaemia using P. falciparum MSP2 as a marker while Restriction Fragment Length Polymorphism (RFLP) was used to identify P. falciparum SP-resistance molecular markers at codons 51, 59, 108, 164 of dihydrofolate reductase (dhfr), and codons 437, 540, 581 and 431 of dihydropteorate synthetase (dhps) genes. The prevalence of malaria from the 410 pregnant women examined at first antenatal registration were 8.29% and 17.07% using RDT and microscopy, respectively (P 0.05). Single mutation of C59R in 10 (21.28%) cases was the most prevalent haplotype in the Pfdhfr/Pfdhps genes (P < 0.05). Mutation variations of Pfdhfr/Pfdhps identified were 15 (31.91%) single, 14 (29.79%) double, 13 (27.66%) triple and 5 (10.64%) quadruple with 5, 8, 6 and 3 unique haplotypes, respectively. The study recorded the presence of malaria parasites among the study participants. P. falciparum SP resistant genes were also detected and this may present a challenge in the usefulness of Intermittent Preventive Treatment (IPTp-SP) in pregnancy.

Molecular surveillance of putative drug resistance markers of antifolate and artemisinin among imported Plasmodium falciparum in Qatar

ABSTRACTMalaria remains a significant public health challenge and is of global importance. Imported malaria is a growing problem in non-endemic areas throughout the world and also in Qatar due to a massive influx of migrants from endemic countries. Antimalarial drug resistance is an important deterrent in our fight against malaria today. Molecular markers mirror intrinsic antimalarial drug resistance and their changes precede clinical resistance. Thus, in the present study, molecular markers of sulphadoxine-pyrimethamine (Pfdhfr and Pfdhps) and artemisinin (PfATPase6 and Pfk13) were sequenced to determine the drug resistance genotypes among 118 imported P. falciparum isolates in Qatar, between 2013 and 2016. All the isolates had mutant Pfdhfr alleles, with either double mutant (51I/108N) (59.3%) or triple mutant (51I, 59R and 108N) (30.6%) genotypes. I164L substitution was not found in this study. In case of Pfdhps, majority of the samples were carriers of either single (S436A/ A437G/ K540E) mutant (47.2%) or double (S436A/K540E, A437G/K540E, K540E/A581G) mutant (39.8%). A single novel point mutation (431V) was observed in the samples originated from Nigeria and Ghana. Polymorphisms in PfATPase6 were absent and only one non-synonymous mutation in Pfk13 was found at codon G453A from a sample of Kenyan origin. High levels of sulphadoxine-pyrimethamine resistance in the present study provide potential information about the spread of antimalarial drug resistance and will be beneficial for the treatment of imported malaria cases in Qatar.

PO 8502 DETERMINANTS AND PREVALENCE OF PARASITE RESISTANCE AMONG PREGNANT WOMEN RECEIVING IPTP WITH SULPHADOXINE-PYRIMETHAMINE IN NIGERIA

BackgroundMalaria in pregnancy carries a risk of significant adverse maternal and infant outcomes. Intermittent preventive treatment in pregnancy (IPTp) is advocated to reduce its occurrence, but resistance to sulphadoxine-pyrimethamine (SP) is being reported. This study aims to describe the burden of SP resistance and determinants of its occurrence among pregnant women receiving IPTp in Nigeria.MethodsA prospective observational study is to be conducted in Ogun State over 24 months. Pregnant women 16–28 weeks gestation meeting the eligibility criteria are being enrolled; blood samples are taken for analysis pre- and post- IPTp-SP administration at scheduled intervals. Microscopy-confirmed parasitaemic samples will be analysed using PCR to detect drug resistance markers (pfdhfr and pfdhps). Participants will be followed up until 28 days post-delivery and assessed for maternal and foetal outcomes (anaemia, low birth weight, preterm delivery, placental parasitaemia, stillbirth, neonatal death). The primary endpoint is the prevalence of the SP resistance gene markers. Secondary endpoints include the prevalence of peripheral and placental parasitaemia at delivery; incidence of maternal and newborn morbidity; parasitaemia pre-IPTp and day 28 post-IPTp; risk factors for SP resistance and haemoglobin changes at delivery.ResultsFollowing statistical analysis with STATA 14, results will be displayed in appropriate formats. Geometric mean parasite densities with 95% confidence intervals will be calculated, and proportions compared using the t-test, Chi-square or Fisher’s exact tests as appropriate. Multivariate analysis including logistic regression models will be used to test for associations between maternal characteristics and SP resistance. Level of significance will be set at p&lt;0.05.ConclusionIn a malaria-endemic country like Nigeria with a large at-risk population, information on the effectiveness of chemoprevention is essential. Determining the proportion and extent of relevant molecular markers within the population offers an invaluable tool for epidemiological surveillance of SP resistance within this endemic setting.

Prevalence of chloroquine and antifolate drug resistance alleles in Plasmodium falciparum clinical isolates from three areas in Ghana.

Background: The emergence and spread of resistance in Plasmodium falciparum to chloroquine (CQ) necessitated the change from CQ to artemisinin-based combination therapies (ACTs) as first-line drug for the management of uncomplicated malaria in Ghana in 2005. Sulphadoxine-pyrimethamine (SP) which was the second line antimalarial drug in Ghana, was now adopted for intermittent preventive treatment of malaria in pregnancy (IPTp). Methods: To examine the prevalence of molecular markers associated with CQ and antifolate drug resistance in Ghana, we employed restriction fragment length polymorphism polymerase chain reaction to genotype and compare single nucleotide polymorphisms (SNPs) in the P. falciparum chloroquine resistance transporter ( pfcrt, PF3D7_0709000), multidrug resistance ( pfmdr1, PF3D7_0523000), bifunctional dihydrofolate reductase-thymidylate synthase ( pfdhfr, PF3D7_0417200) and dihydropteroate synthase ( pfdhps, PF3D7_0810800) genes. Parasites were collected from children with malaria reporting to hospitals in three different epidemiological areas of Ghana (Accra, Kintampo and Navrongo) in 2012-2013 and 2016-2017. Results: The overall prevalence of the CQ resistance-associated pfcrt 76T allele was 8%, whereas pfmdr1 86Y and 184F alleles were present in 10.2% and 65.1% of infections, respectively. The majority of the isolates harboured the antifolate resistance-associated pfdhfr alleles 51I (83.4%), 59R (85.9 %) and 108N (90.5%). Pfdhps 437G and 540E were detected in 90.6% and 0.7% of infections, respectively. We observed no significant difference across the three study sites for all the polymorphisms except for pfdhps 437G , which was more common in Accra compared to Kintampo for the 2016-2017 isolates. Across both pfdhfr and pfdhps genes, a large proportion (61%) of the isolates harboured the quadruple mutant combination ( I 51 R 59 N 108/ G 437). CQ resistance alleles decreased during the 12 years after CQ withdrawal, but an mediate SP resistance alleles increased. Conclusion: Surveillance of the prevalence of resistance alleles is necessary in monitoring the efficacy of antimalarial drugs.

Prevalence of chloroquine and antifolate drug resistance alleles in Plasmodium falciparum clinical isolates from three areas in Ghana

Background: The emergence and spread of resistance in Plasmodium falciparum to chloroquine (CQ) necessitated the change from CQ to artemisinin-based combination therapies (ACTs) as first-line drug for the management of uncomplicated malaria in Ghana in 2005. Sulphadoxine-pyrimethamine (SP) which was the second line antimalarial drug in Ghana, was now adopted for intermittent preventive treatment of malaria in pregnancy (IPTp). Methods: To examine the prevalence of molecular markers associated with CQ and antifolate drug resistance in Ghana, we employed restriction fragment length polymorphism polymerase chain reaction to genotype and compare single nucleotide polymorphisms (SNPs) in the P. falciparum chloroquine resistance transporter ( pfcrt, PF3D7_0709000), multidrug resistance ( pfmdr1, PF3D7_0523000), bifunctional dihydrofolate reductase-thymidylate synthase ( pfdhfr, PF3D7_0417200) and dihydropteroate synthase ( pfdhps, PF3D7_0810800) genes. Parasites were collected from children with malaria reporting to hospitals in three different epidemiological areas of Ghana (Accra, Kintampo and Navrongo) in 2012-2013 and 2016-2017. Results: The overall prevalence of the CQ resistance-associated pfcrt 76T allele was 8%, whereas pfmdr1 86Y and 184F alleles were present in 10.2% and 65.1% of infections, respectively. The majority of the isolates harboured the antifolate resistance-associated pfdhfr alleles 51I (83.4%), 59R (85.9 %) and 108N (90.5%). Pfdhps 437G and 540E were detected in 90.6% and 0.7% of infections, respectively. We observed no significant difference across the three study sites for all the polymorphisms except for pfdhps 437G , which was more common in Accra compared to Kintampo for the 2016-2017 isolates. Across both pfdhfr and pfdhps genes, a large proportion (61%) of the isolates harboured the quadruple mutant combination ( I 51 R 59 N 108/ G 437). CQ resistance alleles decreased during the 12 years after CQ withdrawal, but an mediate SP resistance alleles increased. Conclusion: Surveillance of the prevalence of resistance alleles is necessary in monitoring the efficacy of antimalarial drugs.

Distribution of Mutations Associated with Antifolate and Chloroquine Resistance among Imported Plasmodium vivax in the State of Qatar.

Plasmodium vivax is the most prevalent parasite worldwide, escalating by spread of drug resistance. Currently, in Qatar, chloroquine (CQ) plus primaquine are recommended for the treatment of P. vivax malaria. The present study examined the prevalence of mutations in dihydrofolate reductase (dhfr), dihydropteroate synthase (dhps) genes and CQ resistance transporter (crt-o) genes, associated with sulphadoxine-pyrimethamine (SP) and chloroquine resistance, among imported P. vivax cases in Qatar. Blood samples were collected from patients positive for P. vivax and seeking medical treatment at Hamad General Hospital, Doha, during 2013-2016. The Sanger sequencing method was performed to examine the single nucleotide polymorphisms in Pvdhfr, Pvdhps, and Pvcrt-o genes. Of 314 examined P. vivax isolates, 247 (78.7%), 294 (93.6%) and 261 (83.1%) were successfully amplified and sequenced for Pvdhfr, Pvdhps, and Pvcrt-o, respectively. Overall, 53.8% (N = 133) carried mutant alleles (58R/117N) in Pvdhfr, whereas 77.2% (N = 227) and 90% (N = 235) isolates possessed wild type allele in Pvdhps and Pvcrt-o genes, respectively. In addition, a total of eleven distinct haplotypes were detected in Pvdhfr/Pvdhps genes. Interestingly, K10 insertion in the Pvcrt-o gene was observed only in patients originating from the Indian subcontinent. The results suggested that CQ remains an acceptable treatment regimen but further clinical data are required to assess the effectiveness of CQ and SP in Qatar to support the current national treatment guidelines. In addition, limited distribution of genetic polymorphisms associated with CQ and SP resistance observed in imported P. vivax infections, necessitates regular monitoring of drug resistant P. vivax malaria in Qatar.

Presence of quintuple dhfr N51, C59, S108 – dhps A437, K540 mutations in Plasmodium falciparum isolates from pregnant women and the general population in Nanoro, Burkina Faso

Sulphadoxine-pyrimethamine (SP) is only used for intermittent preventive treatment during pregnancy (IPTp) in most Sub-Saharan African countries. However, there are concerns about the efficacy of IPTp-SP because of increasing resistance. Combinations of point mutations in the dhps and dhfr genes of Plasmodium falciparum are associated with SP resistance, in particular the quintuple dhfr (N51, C59, S108) − dhps (codons A437, K540) mutant. In Nanoro, Burkina Faso, filter paper samples from pregnant women at first antenatal care visit and at delivery plus samples from the general population (GP) were studied for dhfr and dhps mutations by sequencing. Quintuple mutants were present in 2 delivery and 4 GP samples. This is the first time the quintuple mutation is found in Burkina Faso and although the prevalence is still very low, emergence of the quintuple mutation could highly diminish the efficacy of IPTp-SP. Close surveillance of SP resistance mutations is therefore warranted.

Polymorphisms in pfdhfr and pfdhps genes after five years of artemisinin combination therapy (ACT) implementation from urban Kolkata, India

BackgroundIn India, sulphadoxine-pyrimethamine (SP) is now in use as a partner drug of ACT (AS+SP) to treat uncomplicated falciparum malaria since 2010. Declined trend of AS+SP efficacy has been reported from north-eastern states of the country. It is not possible to determine the efficacy of SP alone from any study with ACT. So, this work was designed to study the pattern of polymorphisms in pfdhfr and pfdhps genes to predict the SP resistance status among parasite population of urban Kolkata after five years of ACT implementation. MethodsA total of 125 P. falciparum positive patients were enrolled in the study during December 2014 to July 2016 and treated with AS+SP. Parasitic DNA was isolated and subjected to sequencing of pfdhfr and pfdhps genes directly from purified PCR products. ResultsGenotyping of both the genes was successfully done in 113 isolates. In pfdhfr, 94.69% (107/113) isolates showed mutations at codon 59 and 108. A double mutant genotype ANRNI was mostly prevalent (107/113, 94.69%), while wild-type genotype ANCSI was found only in 5.3% (6/113) isolates. In pfdhps, mutations were recorded at codon 436 and 437 in 65.49% (74/113) and 23.01% (26/113) isolates, respectively. In combined pfdhfr-pfdhps genes, triple mutant ANRNI-FAKAA was most prevalent (45/113, 39.82%) followed by double mutant ANRNI-SAKAA (37/113, 32.74%) and quadruple mutant ANRNI-FGKAA (24/113, 21.24%). ConclusionSP resistance hallmark mutations i.e., quadruple (AIRNI-SAEAA) or quintuple (AIRNI-SGEAA) genotype in pfdhfr and pfdhps was absent which indicates that SP components of used ACT is still effective in the study area. It is also evident by the clinical response of AS+SP. Monitoring the efficacy of this combination (both by therapeutic and molecular marker study) at a regular interval is highly suggested to record any development of SP resistance in near future.

Estimated impact on birth weight of scaling up intermittent preventive treatment of malaria in pregnancy given sulphadoxine-pyrimethamine resistance in Africa: A mathematical model.

BackgroundMalaria transmission has declined substantially in the 21st century, but pregnant women in areas of sustained transmission still require protection to prevent the adverse pregnancy and birth outcomes associated with malaria in pregnancy (MiP). A recent call to action has been issued to address the continuing low coverage of intermittent preventive treatment of malaria in pregnancy (IPTp). This call has, however, been questioned by some, in part due to concerns about resistance to sulphadoxine-pyrimethamine (SP), the only drug currently recommended for IPTp.Methods and findingsUsing an existing mathematical model of MiP, we combined estimates of the changing endemicity of malaria across Africa with maps of SP resistance mutations and current coverage of antenatal access and IPTp with SP (IPTp-SP) across Africa. Using estimates of the relationship between SP resistance mutations and the parasitological efficacy of SP during pregnancy, we estimated the varying impact of IPTp-SP across Africa and the incremental value of enhancing IPTp-SP uptake to match current antenatal care (ANC) coverage.The risks of MiP and malaria-attributable low birthweight (mLBW) in unprotected pregnancies (i.e., those not using insecticide-treated nets [ITNs]) leading to live births fell by 37% (33%–41% 95% credible interval [crI]) and 31% (27%–34% 95% crI), respectively, from 2000 to 2015 across endemic areas in sub-Saharan Africa. However, these gains are fragile, and coverage is far from optimal. In 2015, 9.5 million (8.3 million–10.4 million 95% crI) of 30.6 million pregnancies in these areas would still have been infected with Plasmodium falciparum without intervention, leading to 750,000 (390,000–1.1 million 95% crI) mLBW deliveries. In all, 6.6 million (5.6 million–7.3 million 95% crI) of these 9.5 million (69.3%) pregnancies at risk of infection (and 53.4% [16.3 million/30.6 million] of all pregnancies) occurred in settings with near-perfect SP curative efficacy (>99%) based on the most recent estimates of resistance. Forty-four percent of these pregnancies (23% of all pregnancies) were not receiving any IPTp-SP despite making ≥3 ANC visits, representing 160,000 (94,000–236,000 95% crI) preventable low birthweight (LBW) deliveries. Only 4% (1.4 million) of pregnancies occurred in settings with >10% prevalence of the sextuple haplotype associated with compromised SP effectiveness. Forty-two percent of all pregnancies occurred in settings where the quintuple dhfr/dhps haplotype had become established but where in vivo efficacy data suggest SP maintains the majority of its effectiveness in clearing infections.Not accounting for protection from the use of ITNs during pregnancy, expanding IPTp-SP to all women with ≥3 ANC visits in Africa could prevent an additional 215,000 (128,000–318,000 95% crI) LBW deliveries. In 26 countries with sufficient recent data to estimate ITN impact (population-based ITN usage data that can be stratified by gravidity), we estimate that, due primarily to low ITN use by primigravidae, only 16.5% of the potential LBW births prevented by scaling up IPTp-SP would in fact have already have been prevented through ITN use.Our analysis also highlights the difficulties associated with estimating the relationship between the effectiveness of interventions against parasitological endpoints such as placental infection at delivery and health outcomes including birthweight, which is also determined by a wide range of unrelated factors. We also did not capture other aspects of malaria burden such as clinical malaria, maternal and neonatal anaemia, and miscarriage, all of which increase the overall importance of effective preventative strategies but have their own relationship with transmission intensity, parity, and SP resistance.ConclusionsDespite recent declines in malaria transmission in Africa, the burden of MiP in the absence of adequate prevention remains substantial. Even accounting for SP resistance, extending IPTp-SP to all women attending ANC, as well as long-lasting insecticidal net distribution targeted towards first-time mothers, would have a sizeable impact upon maternal and infant health in almost all malaria-endemic settings in sub-Saharan Africa.

Seasonal Malaria Chemoprevention with Sulphadoxine-Pyrimethamine and Amodiaquine Selects Pfdhfr-dhps Quintuple Mutant Genotype in Mali

BackgroundSeasonal malaria chemoprevention (SMC) with sulphadoxine-pyrimethamine (SP) plus amodiaquine (AQ) is being scaled up in Sahelian countries of West Africa. However, the potential development of Plasmodium falciparum resistance to the respective component drugs is a major concern.MethodsTwo cross-sectional surveys were conducted before (August 2012) and after (June 2014) a pilot implementation of SMC in Koutiala, Mali. Children aged 3–59 months received 7 rounds of curative doses of SP plus AQ over two malaria seasons. Genotypes of P. falciparum Pfdhfr codons 51, 59 and 108; Pfdhps codons 437 and 540, Pfcrt codon 76 and Pfmdr1codon 86 were analyzed by PCR on DNA from samples collected before and after SMC, and in non-SMC patient population as controls (November 2014).ResultsIn the SMC population 191/662 (28.9%) and 85/670 (12.7%) of children were P. falciparum positive by microscopy and were included in the molecular analysis before (2012) and after SMC implementation (2014), respectively. In the non-SMC patient population 220/310 (71%) were successfully PCR analyzed. In the SMC children, the prevalence of all molecular markers of SP resistance increased significantly after SMC including the Pfdhfr-dhps quintuple mutant genotype, which was 1.6% before but 7.1% after SMC (p = 0.02). The prevalence of Pfmdr1-86Y significantly decreased from 26.7% to 15.3% (p = 0.04) while no significant change was seen for Pfcrt 76T. In 2014, prevalence of all molecular markers of SP resistance were significantly higher among SMC children compared to the non-SMC population patient (p < 0.01). No Pfdhfr-164 mutation was found neither at baseline nor post SMC.ConclusionSMC increased the prevalence of molecular markers of P. falciparum resistance to SP in the treated children. However, there was no significant increase of these markers of resistance in the general parasite population after 2 years and 7 rounds of SMC.

Retrospective Investigation of Pyrimethamine-Sulfadoxine Resistance Indicators in Falciparum - Malaria Positive Blood Samples from South - Western Saudi Arabia

The efficacy of Sulphadoxine/Pyrimethamine (SP) in Plasmodium falciparum malaria treatment was increasingly compromised by development of parasites' resistance. Saudi Arabia shifted to new combinations including Artesunat compound during the last decade. We investigated the occurrence of mutations in P. falciparum dihydrofolate reductase (Pfdhfr) N51I, C59R and S108N and P. falciparum dihyropteroate synthetase (Pfdhps) A437G and K540D as major indicators of SP resistance in stored DNA extracts of 41 P. falciparum infected specimens collected from KSA southern endemic regions between 2012 and 2014. Analysis of alleles' polymorphisms by Nested-PCR-RFLP showed that 68%, 7%, and 24% of samples carried parasites with Pfdhfr 51I, 59R, and 108N mutant type alleles, respectively. Only one isolate's genotype shared both mutations 51I and 108N. All parasites conserved wild type alleles at codons 437 and 540 of Pfdhps gene.

RETROSPECTIVE INVESTIGATION OF PYRIMETHAMINE-SULFADOXINE RESISTANCE INDICATORS IN FALCIPARUM-MALARIA POSITIVE BLOOD SAMPLES FROM SOUTH-WESTERN SAUDI ARABIA

The efficacy of Sulphadoxine/Pyrimethamine (SP) in Plasmodium falciparum malaria treatment was increasingly compromised by development of parasites' resistance. Saudi Arabia shifted to new combinations including Artesunat compound during the last decade. We investigated the occurrence of mutations in P. falciparum dihydrofolate reductase (Pfdhfr) N51I, C59R and S108N and P. falciparum dihyropteroate synthetase (Pfdhps) A437G and K540D as major indicators of SP resistance in stored DNA extracts of 41 P. falciparum infected specimens collected from KSA southern endemic regions between 2012 and 2014. Analysis of alleles' polymorphisms by Nested-PCR-RFLP showed that 68%, 7%, and 24% of samples carried parasites with Pfdhfr 51I, 59R, and 108N mutant type alleles, respectively. Only one isolate's genotype shared both mutations 51I and 108N. All parasites conserved wild type alleles at codons 437 and 540 of Pfdhps gene.