Temporal evolution of the resistance genotypes of Plasmodium falciparum in isolates from Equatorial Guinea during 20 years (1999 to 2019)

Abstract Background Malaria is one of the deadliest diseases in the world, particularly in Africa. As such, resistance to anti-malarial drugs is one of the most important problems in terms of global malaria control. This study assesses the evolution of the different resistance markers over time and the possible influence of interventions and treatment changes that have been made in Equatorial Guinea. Methods A total of 1223 biological samples obtained in the period 1999 to 2019 were included in the study. Screening for mutations in the pfdhfr, pfdhps, pfmdr1, and pfcrt genes was carried out by nested PCR and restriction-fragment length polymorphisms (RFLPs), and the study of pfk13 genes was carried out by nested PCR, followed by sequencing to determine the presence of mutations. Results The partially and fully resistant haplotypes (pfdhfr + pfdhps) were found to increase over time. Moreover, in 2019, the fully resistant haplotype was found to be increasing, although its super-resistant counterpart remains much less prevalent. A continued decline in pfmdr1 and pfcrt gene mutations over time was also found. The number of mutations detected in pfk13 has increased since 2008, when artemisinin-based combination therapy (ACT) were first introduced, with more mutations being observed in 2019, with two synonymous and five non-synonymous mutations being detected, although these are not related to resistance to ACT. In addition, the non-synonymous A578S mutation, which is the most frequent on the African continent, was detected in 2013, although not in the following years. Conclusions Withdrawal of the use of chloroquine (CQ) as a treatment in Equatorial Guinea has been shown to be effective over time, as wild-type parasite populations outnumber mutant populations. The upward trend observed in sulfadoxine-pyrimethamine (SP) resistance markers suggest its misuse, either alone or in combination with artesunate (AS) or amodiaquine (AQ), in some areas of the country, as was found in a previous study conducted by this group, which allows selective pressure from SP to continue. Single nucleotide polymorphisms (SNPs) 540E and 581G do not exceed the limit of 50 and 10%, respectively, thus meaning that SP is still effective as an intermittent preventive treatment (IPT) in this country. As for the pfk13 gene, no mutations have been detected in relation to resistance to ACT. However, in 2019 there is a greater accumulation of non-synonymous mutations compared to years prior to 2008. Graphical Abstract

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Temporal Evolution of the Resistance Genotypes of Plasmodium Falciparum in Isolates From Equatorial Guinea During 20 Years (1999 to 2019).

10.21203/rs.3.rs-903234/v1 ◽

2021 ◽

Author(s):

Pedro Berzosa ◽

Irene Molina-de la Fuente ◽

Thuy-Huong Ta-Tang ◽

Vicenta González ◽

Luz García ◽

...

Keyword(s):

Nested Pcr ◽

Gene Mutations ◽

Equatorial Guinea ◽

Upward Trend ◽

Synonymous Mutations ◽

Treatment Changes ◽

Resistance Markers ◽

Parasite Populations ◽

Over Time ◽

Made In

Abstract Background: Malaria is one of the deadliest disease in the world, particularly in Africa. The resistance to antimalarial drugs is one of the most important problems to global malaria control. The study assess the evolution of the different resistance markers over time and the possible influence of the interventions and treatment changes that have been made in Equatorial Guinea.Methods: 1223 biological samples distributed from 1999 to 2019 were included in the study. The screening of the mutations in pfdhfr, pfdhps, pfmdr1 and pfcrt genes were carried out by nested PCR and RFLPs, and the study of pfk13 genes was carried out by nested PCR, followed by sequencing to determine the presence of mutations Results: the haplotypes partially and fully resistant (pfdhfr + pfdhps) increase over time. In 2019, the fully resistant is increasing although super resistant remains lower. There is also a continued decline over time in pfmdr1 and pfcrt gene mutations. Since 2008, when ACTs were introduced in the country, the number of mutations detected in pfk13 has been increasing over time, with more mutations being observed in 2019. In this year, were detected 2 synonymous and 5 non-synonymous mutations, although are not related to resistance to ACTs. In addition, the non-synonymous A578S mutation, the most frequent on the African continent, was detected in 2013, although it has not been detected in the following years.Conclusions: The withdrawal of the use of CQ as a treatment in the country has been effective over time, as wild-type parasite populations outnumber mutant populations. The upward trend observed in SP resistance markers evidence its misuse alone or in combination with AS or AQ in some areas of the country, this allows selective pressure from SP to continue. SNPs 540E and 581G do not exceed the limit of 50% and 10% respectively, which means that SP as an IPT is still effective in the country. As for the pfk13 gene, no mutations have been detected in relation to resistance to ACTs. However, in 2019 there is a greater accumulation of non-synonymous mutations compared to years prior to 2008.

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Single Nucleotide Polymorphisms of Pfdhfr and Pfdhps Genes: Implications for Malaria Prophylactic Strategies in Maiduguri, Northeast Nigeria

Journal of Tropical Medicine ◽

10.1155/2021/8840089 ◽

2021 ◽

Vol 2021 ◽

pp. 1-7

Author(s):

Sulayman Tunde Balogun ◽

Umar Kyari Sandabe ◽

Olufunke Adebola Sodipo ◽

Kenneth Okwong Okon ◽

Ayodele Oluwasoji Akanmu

Keyword(s):

Single Nucleotide Polymorphisms ◽

Geometric Mean ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Dried Blood Spot ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Double Mutation ◽

Blood Spot ◽

Northeast Nigeria

Background. The success of Intermittent Preventive Treatment in Pregnancy (IPTp), Intermittent Preventive Treatment in Infancy (IPTi), and Seasonal Malaria Chemoprevention (SMC) depends on sulfadoxine-pyrimethamine (SP) efficacy. Objective. The study determined Single Nucleotide Polymorphisms (SNPs) of Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) in Maiduguri, Northeast Nigeria. Materials and Methods. Giemsa-stained blood smears, capillary blood, and dried blood spot samples were collected from 63 subjects with uncomplicated malaria in Maiduguri between May and October 2018. Plasmodium species was determined and parasite density (PD) was estimated using the smears. Genomic DNA (gDNA) of P. falciparum was extracted from the dried blood spot samples using QIAamp DNA Mini Kit. The gDNA was subjected to nested PCR followed by restriction fragment length polymorphism (RFLP) to determine SNPs at Pfdhfr codons N51I, C59R, and S108N and Pfdhps codons S436A/F, A437G, and K540E. Results. The subjects’ mean age ± standard deviation was 23.6 ± 8.7 (2.0–67.0) years with a geometric mean PD of 8,948 (2,100–13,400) asexual parasites/µl blood. SNPs prevalence at any of the six Pfdhfr and Pfdhps codons was 85.7% (54/63); the prevalence was higher ( p < 0.05 ) in Pfdhfr (82.5%; 52/63) than Pfdhps (58.7%; 37/63). Pfdhfr allele 108N (82.5%; 52/63) was the highest ( p < 0.05 ) mutant when compared with alleles 51I (60.3%; 38/63) and 59R (66.7%; 42/63). Triple Pfdhfr mutation was observed in 60.3% (38/63) of the isolates and was higher ( p < 0.05 ) among female subjects and SP recipients. Prevalence of Pfdhps allele 436A (28.6%; 18/63) was similar ( p > 0.05 ) to allele 437G (34.9%; 22/63), with double mutation recorded in 4.8% (3/63). K540E mutation was not observed. Conclusion. Pfdhfr and Pfdhps mutations observed in Maiduguri are suggestive of SP resistance level, and this could constitute a setback to malaria prophylactic strategies in the region if unchecked. Thus, there is a need to investigate the clinical efficacy of SP.

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

AAS Open Research ◽

10.12688/aasopenres.12825.2 ◽

2018 ◽

Vol 1 ◽

pp. 1

Author(s):

James Abugri ◽

Felix Ansah ◽

Kwaku P. Asante ◽

Comfort N. Opoku ◽

Lucas A. Amenga-Etego ◽

...

Keyword(s):

Drug Resistance ◽

Plasmodium Falciparum ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Chloroquine Resistance ◽

Nucleotide Polymorphisms ◽

Chloroquine Resistance Transporter ◽

Significant Difference ◽

Quadruple Mutant ◽

Study Sites

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.

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Prevalence and factors associated with carriage of Pfmdr1 polymorphisms among pregnant women receiving intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and artemether-lumefantrine for malaria treatment in Burkina Faso

Malaria Journal ◽

10.1186/s12936-020-03473-5 ◽

2020 ◽

Vol 19 (1) ◽

Author(s):

Hamtandi Magloire Natama ◽

Rouamba Toussaint ◽

Djamina Line Cerine Bazié ◽

Sékou Samadoulougou ◽

Maminata Coulibaly-Traoré ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Burkina Faso ◽

Pregnant Women ◽

Mutant Allele ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Dried Blood Spots ◽

Nucleotide Polymorphisms ◽

High Coverage ◽

Factors Associated

Abstract Background Single nucleotide polymorphisms occurring in the Plasmodium falciparum multidrug resistant gene 1 (pfmdr1) are known to be associated with aminoquinoline resistance and, therefore, represent key P. falciparum markers for monitoring resistance both in susceptible groups (children under 5 years old and pregnant women) and in the general population. This study aimed to determine prevalence and factors associated with the carriage of pfmdr1 N86Y, Y184F and D1246Y polymorphisms among pregnant women in a setting of high malaria transmission in Burkina Faso. Methods Plasmodium falciparum isolates were collected at the first antenatal care visit (ANC-1) as well as at delivery from pregnant women participating in the COSMIC trial (NTC01941264), which assessed malaria preventive interventions during pregnancy in the Nanoro Health District. Here, pregnant women received intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and malaria infections and/or diseases were treated using artemether-lumefantrine (AL) during the trial. Parasite DNA was extracted from dried blood spots and the presence of pfmdr1 mutations at positions 86, 184 and 1246 was determined using nested PCR, followed by restriction fragment length polymorphism (RFLP) analysis. Results A prevalence of 13.2% (20/151) and 12.1% (14/116) of the pfmdr1 86Y mutant allele was found at ANC-1 and at delivery, respectively, while no mutant allele was observed for Y184F and D1246Y codons at both ANC-1 and at delivery. There were no significant factors associated with pfmdr1 86Y mutant allele carriage at ANC-1. However, malaria infections at delivery with a parasite density above the median (2237.2 (IQR: 613.5–11,425.7) parasites/µl) was associated with an increase risk of pfmdr1 86Y mutant allele carriage (AOR = 5.5 (95% CI 1.07–28.0); P = 0.04). In contrast, both three or more IPTp-SP doses (AOR = 0.25 (95% CI 0.07–0.92); P = 0.04) and one or more AL treatment (AOR = 0.25 (95% CI 0.07–0.89); P = 0.03) during pregnancy were associated with a significant reduce risk of pfmdr1 86Y mutant allele carriage at delivery. Conclusion These findings suggest that both high coverage of IPTp-SP and the use of AL for the treatment of malaria infection/disease during pregnancy select for pfmdr1 N86 wild-type allele at delivery.

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

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00507-15 ◽

2015 ◽

Vol 59 (9) ◽

pp. 5475-5482 ◽

Cited By ~ 14

Author(s):

Anthony K. Mbonye ◽

Josephine Birungi ◽

Stephanie K. Yanow ◽

Sandra Shokoples ◽

Samuel Malamba ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Birth Weight ◽

Pregnant Women ◽

Intermittent Preventive Treatment ◽

Melting Curve ◽

Preventive Treatment ◽

Melting Curve Analysis ◽

Content Type ◽

Lower Birth Weight ◽

Resistance Markers

ABSTRACTThe aim of this study was to assess the prevalence of mutations inPlasmodium falciparumdihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes among pregnant women using sulfadoxine-pyrimethamine (SP) as an intermittent preventive treatment (IPTp). A molecular epidemiological study ofP. falciparumparasite resistance markers to SP was conducted from August 2010 to February 2012 in Mukono district in central Uganda. DNA was extracted from 413P. falciparum-positive samples. Real-time PCR, followed by melting curve analysis, was used to characterize point mutations in thePfdhfrandPfdhpsgenes that are associated with SP resistance. The prevalence of the single-nucleotide mutations inPfdhfrat codons 51I, 59R, and 108N and inPfdhpsat 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 ofPfdhfrandPfdhpsquintuple 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 ofPfdhfrandPfdhpsquintuple mutations throughout pregnancy excluded further analyses of possible associations between certain haplotypes and the risk of lower birth weight and anemia. However, women infected withP. falciparumhad 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 wereP. falciparumpositive at baseline became negative after one or two doses of SP (i.e., 50.5%), implying that SP-IPTp still has some efficacy.P. falciparumresistance markers to SP are high in this population, whereasP. falciparuminfection was associated with poor birth outcomes.

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Drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon: a systematic review and meta-analysis (1998–2020)

Malaria Journal ◽

10.1186/s12936-020-03543-8 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Peter Thelma Ngwa Niba ◽

Akindeh M. Nji ◽

Marie-Solange Evehe ◽

Innocent M. Ali ◽

Palmer Masumbe Netongo ◽

...

Keyword(s):

Systematic Review ◽

Drug Resistance ◽

Resistance Genes ◽

Meta Analysis ◽

Gene Mutations ◽

Artemisinin Resistance ◽

Molecular Data ◽

Nucleotide Polymorphisms ◽

Pooled Prevalence ◽

Resistance Markers

Abstract Background Malaria remains highly endemic in Cameroon. The rapid emergence and spread of drug resistance was responsible for the change from monotherapies to artemisinin-based combinations. This systematic review and meta-analysis aimed to determine the prevalence and distribution of Plasmodium falciparum drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon from January 1998 to August 2020. Methods The PRISMA-P and PRISMA statements were adopted in the inclusion of studies on single nucleotide polymorphisms (SNPs) of P. falciparum anti-malarial drug resistance genes (Pfcrt, Pfmdr1, Pfdhfr, Pfdhps, Pfatp6, Pfcytb and Pfk13). The heterogeneity of the included studies was evaluated using the Cochran’s Q and I2 statistics. The random effects model was used as standard in the determination of heterogeneity between studies. Results Out of the 902 records screened, 48 studies were included in this aggregated meta-analysis of molecular data. A total of 18,706 SNPs of the anti-malarial drug resistance genes were genotyped from 47,382 samples which yielded a pooled prevalence of 35.4% (95% CI 29.1–42.3%). Between 1998 and 2020, there was significant decline (P < 0.0001 for all) in key mutants including Pfcrt 76 T (79.9%-43.0%), Pfmdr1 86Y (82.7%-30.5%), Pfdhfr 51I (72.2%-66.9%), Pfdhfr 59R (76.5%-67.8%), Pfdhfr 108 N (80.8%-67.6%). The only exception was Pfdhps 437G which increased over time (30.4%-46.9%, P < 0.0001) and Pfdhps 540E that remained largely unchanged (0.0%-0.4%, P = 0.201). Exploring mutant haplotypes, the study observed a significant increase in the prevalence of Pfcrt CVIET mixed quintuple haplotype from 57.1% in 1998 to 57.9% in 2020 (P < 0.0001). In addition, within the same study period, there was no significant change in the triple Pfdhfr IRN mutant haplotype (66.2% to 67.3%, P = 0.427). The Pfk13 amino acid polymorphisms associated with artemisinin resistance were not detected. Conclusions This review reported an overall decline in the prevalence of P. falciparum gene mutations conferring resistance to 4-aminoquinolines and amino alcohols for a period over two decades. Resistance to artemisinins measured by the presence of SNPs in the Pfk13 gene does not seem to be a problem in Cameroon. Systematic review registration PROSPERO CRD42020162620

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Temporal evolution of sulfadoxine-pyrimethamine resistance genotypes and genetic diversity in response to a decade of increased interventions against Plasmodium falciparum in northern Ghana

Malaria Journal ◽

10.1186/s12936-021-03693-3 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Lucas N. Amenga-Etego ◽

Victor Asoala ◽

Godfred Agongo ◽

Christopher Jacob ◽

Sonia Goncalves ◽

...

Keyword(s):

Double Mutant ◽

Wellcome Trust Sanger Institute ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Northern Ghana ◽

Seasonal Malaria Chemoprevention ◽

High Prevalence ◽

Resistance Patterns ◽

Combined Genotypes ◽

Over Time

Abstract Background Anti-malarial drug resistance remains a key concern for the global fight against malaria. In Ghana sulfadoxine-pyrimethamine (SP) is used for intermittent preventive treatment of malaria in pregnancy and combined with amodiaquine for Seasonal Malaria Chemoprevention (SMC) during the high malaria season. Thus, surveillance of molecular markers of SP resistance is important to guide decision-making for these interventions in Ghana. Methods A total of 4469 samples from uncomplicated malaria patients collected from 2009 to 2018 was submitted to the Wellcome Trust Sanger Institute, UK for DNA sequencing using MiSeq. Genotypes were successfully translated into haplotypes in 2694 and 846 mono infections respectively for pfdhfr and pfdhps genes and the combined pfhdfr/pfdhps genes across all years. Results At the pfdhfr locus, a consistently high (> 60%) prevalence of parasites carrying triple mutants (IRNI) were detected from 2009 to 2018. Two double mutant haplotypes (NRNI and ICNI) were found, with haplotype NRNI having a much higher prevalence (average 13.8%) than ICNI (average 3.2%) across all years. Six pfdhps haplotypes were detected. Of these, prevalence of five fluctuated in a downward trend over time from 2009 to 2018, except a pfdhps double mutant (AGKAA), which increased consistently from 2.5% in 2009 to 78.2% in 2018. Across both genes, pfdhfr/pfdhps combined triple (NRNI + AAKAA) mutants were only detected in 2009, 2014, 2015 and 2018, prevalence of which fluctuated between 3.5 and 5.5%. The combined quadruple (IRNI + AAKAA) genotype increased in prevalence from 19.3% in 2009 to 87.5% in 2011 before fluctuating downwards to 19.6% in 2018 with an average prevalence of 37.4% within the nine years. Prevalence of parasites carrying the quintuple (IRNI + AGKAA or SGEAA) mutant haplotypes, which are highly refractory to SP increased over time from 14.0% in 2009 to 89.0% in 2016 before decreasing to 78.9 and 76.6% in 2017 and 2018 respectively. Though quintuple mutants are rising in prevalence in both malaria seasons, together these combined genotypes vary significantly within season but not between seasons. Conclusions Despite high prevalence of pfdhfr triple mutants and combined pfdhfr/pfdhps quadruple and quintuple mutants in this setting SP may still be efficacious. These findings are significant as they highlight the need to continuously monitor SP resistance, particularly using deep targeted sequencing to ascertain changing resistance patterns.

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Counter-Selection of Antimalarial Resistance Polymorphisms by Intermittent Preventive Treatment in Pregnancy

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz451 ◽

2019 ◽

Author(s):

Silvie Huijben ◽

Eusebio Macete ◽

Ghyslain Mombo-Ngoma ◽

Michael Ramharter ◽

Simon Kariuki ◽

...

Keyword(s):

Pregnancy Outcomes ◽

Copy Number ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Antimalarial Resistance ◽

Resistance Markers ◽

The Impact ◽

Pfmdr1 Copy Number ◽

Selection Of ◽

In Pregnancy

Abstract Background Innovative approaches are needed to limit antimalarial resistance evolution. Understanding the role of intermittent preventive treatment in pregnancy (IPTp) on the selection for resistance and the impact such selection has on pregnancy outcomes can guide future interventions. Methods Plasmodium falciparum isolates (n = 914) from 2 randomized clinical trials were screened for pfmdr1 copy number variation and pfcrt, pfmdr1, pfdhfr, and pfdhps resistance markers. The trials were conducted between 2010 and 2013 in Benin, Gabon, Kenya, and Mozambique to establish the efficacy of IPTp-mefloquine (MQ) compared with IPTp-sulphadoxine-pyrimethamine (SP) in human immunodeficiency virus (HIV)-uninfected and to IPTp-placebo in HIV-infected women. Results In HIV-uninfected women, the prevalence of pfcrt mutants, pfdhfr/pfdhps quintuple mutants, and pfmdr1 copy number was similar between women receiving IPT-SP and IPTp-MQ. However, prevalence of pfmdr1 polymorphism 86Y was lower in the IPTp-MQ group than in the IPTp-SP group, and within the IPTp-MQ group it was lower at delivery compared with recruitment. No effect of IPTp-MQ on resistance markers was observed among HIV-infected women. The carriage of resistance markers was not associated with pregnancy outcomes. Conclusions Selection of wild-type pfmdr1 polymorphism N86 by IPTp-MQ highlights the strong selective pressure IPTp can exert and the opportunity for using negative cross-resistance in drug choice for clinical treatment and IPTp.

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Low prevalence of highly sulfadoxine‐resistant dihydropteroate synthase alleles in Plasmodium falciparum isolates in Benin

Malaria Journal ◽

10.1186/s12936-021-03605-5 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Samaly Souza Svigel ◽

Adicath Adeothy ◽

Augustin Kpemasse ◽

Ernest Houngbo ◽

Antoine Sianou ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

Nucleotide Polymorphisms ◽

Triple Mutant ◽

Single Nucleotide ◽

Dihydropteroate Synthase ◽

Seasonal Malaria Chemoprevention ◽

Study Sites ◽

Low Prevalence

Abstract Background In 2004, in response to high levels of treatment failure associated with sulfadoxine-pyrimethamine (SP) resistance, Benin changed its first-line malaria treatment from SP to artemisinin-based combination therapy for treatment of uncomplicated Plasmodium falciparum malaria. Resistance to SP is conferred by accumulation of single nucleotide polymorphisms (SNPs) in P. falciparum genes involved in folate metabolism, dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps), targeted by pyrimethamine and sulfadoxine, respectively. Because SP is still used for intermittent preventive treatment in pregnant women (IPTp) and seasonal malaria chemoprevention (SMCP) in Benin, the prevalence of Pfdhfr and Pfdhps SNPs in P. falciparum isolates collected in 2017 were investigated. Methods This study was carried out in two sites where the transmission of P. falciparum malaria is hyper-endemic: Klouékanmey and Djougou. Blood samples were collected from 178 febrile children 6–59 months old with confirmed uncomplicated P. falciparum malaria and were genotyped for SNPs associated with SP resistance. Results The Pfdhfr triple mutant IRN (N51I, C59R, and S108N) was the most prevalent (84.6%) haplotype and was commonly found with the Pfdhps single mutant A437G (50.5%) or with the Pfdhps double mutant S436A and A437G (33.7%). The quintuple mutant, PfdhfrIRN/PfdhpsGE (A437G and K540E), was rarely observed (0.8%). The A581G and A613S mutant alleles were found in 2.6 and 3.9% of isolates, respectively. Six isolates (3.9%) were shown to harbour a mutation at codon I431V, recently identified in West African parasites. Conclusions This study showed that Pfdhfr triple IRN mutants are near fixation in this population and that the highly sulfadoxine-resistant Pfdhps alleles are not widespread in Benin. These data support the continued use of SP for chemoprevention in these study sites, which should be complemented by periodic nationwide molecular surveillance to detect emergence of resistant genotypes.

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Sulfadoxine-pyrimethamine parasitological efficacy against Plasmodium falciparum among pregnant women and molecular markers of resistance in Zambia: an observational cohort study

Malaria Journal ◽

10.1186/s12936-021-03596-3 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Enesia Banda Chaponda ◽

Sungano Mharakurwa ◽

Charles Michelo ◽

Jane Bruce ◽

Daniel Chandramoha ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Pregnant Women ◽

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

World Health ◽

Treatment And Prevention ◽

Observational Cohort ◽

Gestational Week ◽

Resistance Markers ◽

Health Organization

Abstract Background The World Health Organization recommends the provision of intermittent preventive treatment during pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) at 4-week intervals from gestational week 13 to delivery in areas of moderate to high malaria transmission intensity. However, the effect of IPTp-SP has been compromised in some areas due to parasite resistance, raising the importance of parasitological and chemoprophylactic surveillance, and monitoring SP-resistance markers in the Plasmodium falciparum population. Methods Between November 2013 and April 2014 in Nchelenge, Zambia, 1086 pregnant women received IPTp-SP at antenatal-care bookings. Blood samples were collected on day 0, and on day 28 post-treatment to test for malaria parasites and to estimate SP parasitological efficacy in the treatment and prevention of parasitaemia. A random sample of 96, day 0 malaria-positive samples were analysed to estimate the prevalence of SP-resistance markers in the P. falciparum population. Results The overall parasitological and prophylactic failure among women who had paired day 0 and day 28 blood slides was 18.6% (95% CI 15.5, 21.8; 109 of 590). Among pregnant women who had asymptomatic parasitaemia on day 0, the day 28 PCR-uncorrected parasitological failure was 30.0% (95% CI 23.7, 36.2; 62 of 207) and the day 28 PCR-corrected parasitological failure was 15.6% (95% CI: 10.6, 20.6; 32 of 205). Among women who tested negative at day 0, 12.3% (95% CI: 9.0, 15.6; 47 of 383) developed parasitaemia at day 28. Among the 96 malaria-positive samples assayed from day 0, 70.8% (95% CI: 60.8, 79.2) contained the DHPS double (Gly-437 + Glu-540) mutation and 92.7% (95% CI: 85.3, 96.5) had the DHFR triple (Asn-108 + Ile-51 + Arg-59) mutation. The quintuple mutation (DHFR triple + DHPS double) and the sextuple mutant (DHFR triple + DHPS double + Arg-581) were found among 68.8% (95% CI: 58.6, 77.3) and 9.4% (95% CI: 4.2, 16.0) of samples, respectively. Conclusion The parasitological and chemoprophylactic failure of SP, and the prevalence of resistance markers in Nchelenge is alarmingly high. Alternative therapies are urgently needed to safeguard pregnant women against malarial infection.

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