Sulfadoxine-pyrimethamine Research Articles

Prevalence of molecular markers of sulfadoxine-pyrimethamine resistance in Plasmodium falciparum isolates from West Africa during 2012–2022

Sulfadoxine-pyrimethamine (SP) is a key drug recommended by the World Health Organization for the chemoprevention of malaria. However, the strategy is affected by the parasite resistance to SP. This study evaluated Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes, associated with SP resistance, from 508 P. falciparum isolates imported from West African countries to Henan Province, China, during 2012–2022. High mutant prevalence of the genes Pfdhfr (94.7%) and Pfdhps (96.8%) was observed. The mutants Pfdhfr N51I, C59R, S108N, and Pfdhps A437G were at high frequency in all countries analyzed. The overall prevalence of the mutant Pfdhps K540E was low (3.4%), but with a high frequency in Liberia (24.3%). The frequency of mutants Pfdhps I431V, A581G, and A613S was 11.7%, 9.8%, and 16.2%, respectively, all of which had the highest mutant prevalence in Nigeria. The mutant Pfdhps A581G and A613S were identified in the absence of K540E. The partially resistant haplotype (I51R59N108 - G437) was the most common (72.6%), and the fully resistant haplotype (I51R59N108 - G437E540) had a low prevalence of 3.4% and mainly occurred in Liberia. No super resistant haplotype was identified. The mutant Pfdhps I431V and the octuple mutant haplotype I51R59N108 - V431A436G437G581S613 deserve more attention. In areas of high SP resistance, the intervention still reduces low birthweight and maternal anaemia. SP should continue to be used in areas of high SP resistance until more effective alternatives for malaria chemoprevention are found. It is important to continuously monitor the molecular markers associated with SP resistance to better implement intermittent preventive treatment policies in pregnancy (IPTp) and infants (IPTi).

Intermittent preventive treatment for malaria in pregnancy and infant growth: a mediation analysis of a randomised trial

Intermittent preventive treatment for malaria in pregnancy (IPTp) can improve birth outcomes, but whether it confers benefits to postnatal growth is unclear. We investigated the effect of IPTp on infant growth in Uganda and its pathways of effects using causal mediation analyses. We analysed data from 633 infants born to mothers enrolled in a randomised trial of monthly IPTp with dihydroartemisinin-piperaquine (DP) vs. sulfadoxine-pyrimethamine (SP) (NCT02793622). Weight and length were measured from 0 to 12 months of age. Using generalised linear models, we estimated effects of DP vs. SP on gravidity-stratified mean length-for-age (LAZ) and weight-for-length Z-scores (WLZ). We investigated mediation by placental malaria, gestational weight change, maternal anaemia, maternal inflammation-related proteins, preterm birth, birth length, and birth weight. Mediation models adjusted for infant sex, gravidity, gestational age at enrolment, maternal age, maternal parasitaemia at enrolment, education, and wealth. SP increased mean LAZ by 0.18-0.28 Z from birth through age 4 months compared to DP, while DP increased mean WLZ by 0.11-0.28 Z from 2 to 8 months compared to SP among infants of multigravidae; at these ages, confidence intervals for mean differences excluded 0. We did not observe differences among primigravida. Mediators of SP included birth weight, birth length, maternal stem cell factor, and DNER. Mediators of DP included placental malaria and birth length, maternal IL-18, CDCP1, and CD6 at delivery. In high malaria transmission settings, this exploratory study suggests different IPTp regimens may influence infant growth among multigravidae, potentially through distinct pathways, in the exclusive breastfeeding period, when few other interventions are available. Stanford Center for Innovation in Global Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bill & Melinda Gates Foundation.

Adherence to sulfadoxine-pyrimethamine five-dose policy among pregnant women in an urban slum in Ghana: a mixed-methods study

BackgroundMalaria in pregnancy (MiP) is a public health concern especially for pregnant women living in slums. The World Health Organization recommends at least three doses of Sulfadoxine-Pyrimethamine (SP) to prevent MiP. In Ghana, it is recommended that pregnant women receive a minimum of five doses of the medication. This study sought to determine the level of adherence to IPT5 policy and factors associated with adherence among pregnant women in a slum community in Ghana.MethodsThis was a cross-sectional study involving 232 nursing mothers and four healthcare workers at the St. Martin’s Memorial Hospital, Sukura, Ghana. Sociodemographic characteristics of nursing mothers were obtained using an interview-administered questionnaire. Data on the number of SP doses and other obstetrics characteristics were collected by reviewing the antenatal record books. To obtain information about healthcare and health system factors associated with adherence to the five-dose policy, four healthcare providers were interviewed. A data extraction form was used to obtain information about the availability of SP at the facility.ResultsThe level of adherence to IPT5 was 8.6% (20/232) (95% CI 5.0–12.3) among the participants. Only 8.4% of the participants received their first dose at 16 weeks. Respondents who began ANC in the second trimester were 81% less likely to adhere to IPT5 than those who began in the first trimester (aOR = 0.19, 95% CI 90.01–0.65, p < 0.008). Healthcare provider and health system factors that influence IPT5 uptake include healthcare providers’ knowledge of IPTp-SP guidelines, the practice of Directly Observed Therapy, education of pregnant women, training of healthcare providers, and availability of water. SP was available at the facility during the period of review.ConclusionAdherence to the IPTp-SP five-dose policy was suboptimal. Pregnant women who started ANC early were more likely to adhere to the policy. Provider knowledge, DOT practice, training, education of pregnant women and water availability were also found to influence adherence. Encouraging early ANC visits and providing healthcare workers with necessary training can substantially improve adherence in slum areas.

Drug-Drug Interaction Between Dihydroartemisinin-Piperaquine and Sulfadoxine-Pyrimethamine During Malaria Chemoprevention in Pregnant Women.

Co-administration of dihydroartemisinin-piperaquine (DP) and sulfadoxine-pyrimethamine (SP) for intermittent preventive treatment of malaria in pregnancy (IPTp) may be superior in preventing adverse birth outcomes compared with either therapy alone, but potential drug-drug interactions require investigation. We conducted intensive and sparse pharmacokinetic (PK) studies in a subset of Ugandan women participating in a randomized controlled trial of monthly IPTp with SP vs. DP vs. DP + SP. Intensive PK sampling was performed from day 0 to 23 after dosing at 28 weeks gestation in 87 participants across treatment arms. Sparse sampling was performed on day 28 (trough) after dosing at 20 and 28 gestational weeks in additional 196 participants receiving SP vs. DP + SP. Intensive PK analysis demonstrated that compared with SP alone, co-administration of DP + SP was associated with lower maximal concentrations, the area under the concentration-time curves (AUC), and day 23 concentrations of sulfadoxine (25%, 25%, and 27%) and pyrimethamine (26%, 34%, and 32%) (P < 0.05 for all comparisons). Sparse PK results demonstrated participants co-administered DP + SP had lower trough concentrations after dosing at 20 and 28 gestational weeks for sulfadoxine (6%, P = 0.68 and 31%, P = 0.023, respectively) and pyrimethamine (18%, P = 0.032 and 33%, P < 0.001, respectively) compared with SP alone. Co-administration of DP + SP was associated with a 19% reduction in piperaquine AUC (P = 0.046), but no significant difference in other PK parameters compared with DP alone. In summary, co-administration of DP + SP was associated with significantly reduced SP exposure, with a greater magnitude during the third vs. second trimester. The clinical consequences of this interaction are yet unknown.

Profile of molecular markers of Sulfadoxine-Pyrimethamine-resistant Plasmodium falciparum in individuals living in southern area of Brazzaville, Republic of Congo

BackgroundAlthough the seasonal and perennial malaria chemopreventions are not implemented in the Republic of Congo, resistance to Sulfadoxine-pyrimethamine (SP) threatens the intermittent preventive treatment during pregnancy (IPTp-SP) and others treatments using the drug. The objective of this study was to determine the prevalence of molecular markers of P.falciparum resistance to SP in individuals with microscopic malaria infection in the south of Brazzaville. MethodsTwo parallel surveys (health facilities and community-based cross sectional studies) were carried out in urban and rural areas in southern Brazzaville. Between March and October 2021, blood samples were collected from 328 P. falciparum microscopic positive individuals (1- 83 years old, and sex ratio female/male of 1.1) to characterize dhfr and dhps genes involved in the P.falciparum resistance to SP. Restriction Fragment Length Polymorphism PCR was used for the detection of mutations within these parasite genes. ResultsHigh prevalence of mutations was reported within Pfdhfr gene: N51I; 328/328 (100%) ratio (prevalence) [95 CI uncertainty], C59R; 317/328 (96.6 %) [94.1-98.1%], S108N; 326/326 (100%), N164L; 3/326 (0.9%) [0.3-2.7%], and Pfdhps gene: A437G; 292/327 (89.3%) [85.5-92.2%], K540E; 140/327(42.8 %) [37.6-48.2%], A581G; 136/325 (41.8%) [36.6-42.3%]. The quintuple mutant (N51I+ C59R + S108N + A437G + K540E) and sextuple mutant haplotypes (N51I+ C59R + S108N + A437G + K540E + A581G) were reported for 11/144 (7.6%) [4.3-13.2%] and 5/144 (3.4% ) [1.5-7.9%]) of the participants respectively. The K540E and A437G mutants were more prevalent in the rural community; 81/139 (58.3%) [50.0-66.1%] and 135/139 (97.1%) [92.8-98.9%] respectively) than in the urban community; 21/50 (46.3%) [33.7-59.4%] and 47/54(87.0%) [75.6-93.6%] (p= 0.004 and p˂0.0001 respectively) ConclusionThese results indicate high prevalence of SP resistance mutations within the dhfr and dhps genes of P. falciparum isolates circulating in study sites, which may limit the efficacy of treatments using SP in these settings.

Delivery effectiveness of and adherence to intermittent preventive treatment for malaria in pregnancy with dihydroartemisinin–piperaquine with or without targeted information transfer or sulfadoxine–pyrimethamine in western Kenya: a three-armed, pragmatic, open-label, cluster-randomised trial

Delivery effectiveness of and adherence to intermittent preventive treatment for malaria in pregnancy with dihydroartemisinin–piperaquine with or without targeted information transfer or sulfadoxine–pyrimethamine in western Kenya: a three-armed, pragmatic, open-label, cluster-randomised trial

Impact of oral azithromycin and intermittent preventive treatment with sulfadoxine-pyrimethamine regimen on child mortality in Sierra Leone: trial protocol for a randomised, two-arm, double-blinded, placebo-controlled clinical trial (ICARIA)

BackgroundAzithromycin has been shown to be beneficial in preventing infectious diseases, including malaria, infectious diarrhoea and pneumonia. A cluster randomised control trial on azithromycin MDA in children in Niger, Malawi and Tanzania found a reduction in all-cause under-five (U5) mortality in communities who received azithromycin compared to placebo. However, the reduction was largest and statistically significant only in Niger. The purpose of this trial is to evaluate the impact of azithromycin plus intermittent preventive treatment in infants (IPTi), recently renamed by the World Health Organisation as perennial malaria chemoprevention (PMC), with sulfadoxine-pyrimethamine (SP) on all-cause mortality up to 18 months of age in children living in areas of high mortality burden through the Expanded Program on Immunisation (EPI) in Sierra Leone.MethodsThe Improving Care through Azithromycin Research for Infants in Africa (ICARIA) trial is a phase III two-arm, individually randomised, double-blinded, placebo-controlled trial administering oral AZI (20 mg/kg bodyweight) at three time points to children attending EPI visits in Sierra Leone. A total of 20,560 infants attending the first EPI contact at around 6 weeks of age are recruited and randomised to AZI or placebo in a 1:1 ratio. The second and third AZI/placebo doses are given at 9 and 15 months of age. The primary outcome of the trial is all-cause mortality rate at 18 months of age assessed through mortality surveillance. Other trial outcomes include the impact on antimicrobial resistance, and on the immune response to certain key routine EPI immunisations, the safety of the intervention, the prevalence of SP resistance markers and the feasibility, and acceptability of adding AZI to the EPI programme.DiscussionThe trial will provide the evidence needed to inform policy regarding the adoption and large-scale implementation of AZI in areas of high-mortality burden in sub-Saharan Africa.Trial registrationClinicalTrials.gov NCT04235816. Registered on 22 January 2020.Pan-African Clinical Trials Registry PACTR202004540256535. Registered on 14 April 2020.

Parasite clearance and protection from Plasmodium falciparum infection (PCPI): a three-arm, parallel, double-blinded, placebo-controlled, randomised trial of presumptive sulfadoxine-pyrimethamine versus sulfadoxine-pyrimethamine plus amodiaquine versus artesunate monotherapy among asymptomatic children 3–5 years of age in Cameroon

BackgroundThe World Health Organization 2022 malaria chemoprevention guidelines recommend providing a full course of antimalarial treatment at pre-defined intervals, regardless of malaria status to prevent illness among children resident in moderate to high perennial malaria transmission settings as perennial malaria chemoprevention (PMC) with sulfadoxine-pyrimethamine (SP). The dhps I431V mutation circulating in West Africa has unknown effect on SP protective efficacy.MethodsThis protocol is for a three-arm, parallel, double-blinded, placebo-controlled, randomised trial in Cameroon among children randomly assigned to one of three directly-observed treatment groups: (i) Group 1 (n = 450) receives daily artesunate (AS) placebo on days − 7 to -1, then active SP plus placebo amodiaquine (AQ) on day 0, and placebo AQ on days 1 and 2; (ii) Group 2 (n = 250) receives placebo AS on days − 7 to -1, then active SP and AQ on day 0, and active AQ on days 1 and 2; and (iii) Group 3 (n = 200) receives active AS on days − 7 to -1, then placebo SP on day 0 and placebo AQ on days 0 to 2. On days 0, 2, 5, 7, and thereafter weekly until day 28, children provide blood for thick smear slides. Dried blood spots are collected on the same days and weekly from day 28 to day 63 for quantitative polymerase chain reaction (qPCR) and genotype analyses.DiscussionOur aim is to quantify the chemopreventive efficacy of SP, and SP plus AQ, and measure the effect of the parasite genotypes associated with SP resistance on parasite clearance and protection from infection when exposed to SP chemoprevention. We will report unblinded results including: (i) time-to-parasite clearance among SP and SP plus AQ recipients who were positive on day 0 by qPCR and followed to day 63; (ii) mean duration of SP and SP plus AQ protection against infection, and (iii) mean duration of symptom-free status among SP and SP plus AQ recipients who were parasite free on day 0 by qPCR. Our study is designed to compare the 28-day follow-up of the new WHO malaria chemoprevention efficacy study protocol with extended follow-up to day 63.Trial registrationClinicalTrials.gov NCT06173206; 15/12/2023.

Effectiveness of malaria chemoprevention in the first two years of life in Cameroon and Côte d’Ivoire compared to standard of care: study protocol for a population-based prospective cohort impact evaluation study

BackgroundPerennial malaria chemoprevention (PMC) is a chemoprevention strategy endorsed by the World Health Organization (WHO) and is increasingly being adopted by National Malaria Programmes. PMC aims to reduce morbidity and mortality caused by malaria and anaemia in in young children through provision of antimalarial drugs at routine contact points with the local health system. This study aims to evaluate the impact of the programmatically-implemented country-tailored PMC programmes targeting children up to two years of age using sulfadoxine-pyrimethamine (SP) on the incidence of malaria and anaemia in children in Cameroon and Côte d’Ivoire.MethodsWe will assess the impact of PMC using passive and active monitoring of a prospective observational cohort of children up to 36 months of age at recruitment in selected study sites in Cameroon and Côte d’Ivoire. The primary and secondary outcomes include malaria, anaemia and malnutrition incidence. We will also conduct a time-series analysis of passively detected malaria and anaemia cases comparing the periods before and after PMC introduction. This study is powered to detect a 30% and 40% reduction of malaria incidence compared to the standard of care in Cameroon and Côte d’Ivoire, respectively.DiscussionThis multi-country study aims to provide evidence of the effectiveness of PMC targeting children in the first two years of life on malaria and anaemia and will provide important information to inform optimal operationalization and evaluation of this strategy.Trial RegistrationCameroon - NCT05889052; Côte d’Ivoire - NCT05856357.

Antimalarial drug sulfadoxine induces gametocytogenesis in Plasmodium berghei

BackgroundThe spread of antimalarial drug resistance parasites is a major obstacle in eliminating malaria in endemic areas. This increases the urgency for developing novel antimalarial drugs with improved profiles to eliminate both sensitive and resistant parasites in populations. The invention of the drug candidates needs a model for sensitive and resistant parasites on a laboratory scale.MethodsRepeated Incomplete Treatment (RIcT) method was followed in raising the rodent malaria parasite, Plasmodium berghei, resistant to sulfadoxine. Plasmodium berghei were exposed to an adequate therapeutic dose of sulfadoxine without finishing the treatment to let the parasite recover. Cycles of drug treatment and parasite recovery were repeated until phenotypic resistance appeared.ResultsAfter undergoing 3–4 cycles, phenotypic resistance was not yet found in mice treated with sulfadoxine. Nevertheless, the molecular biology of dhps gene (the target of sulfadoxine) was analyzed at the end of the RIcT cycle. There was no mutations found in the gene target. Interestingly, the appearance of gametocytes at the end of every cycle of drug treatment and parasite recovery was observed. These gametocytes later on would no longer extend their life in the RBC stage, unless mosquitoes bite the infected host. This phenomenon is similar to the case in human malaria infections treated with sulfadoxine-pyrimethamine (SP).ConclusionsIn this study, the antimalarial drug sulfadoxine induced gametocytogenesis in P. berghei, which could raise the risk factor for malaria transmission.

Community-based strategies to increase coverage of intermittent preventive treatment of malaria in pregnancy with sulfadoxine–pyrimethamine in sub-Saharan Africa: a systematic review, meta-analysis, meta-ethnography, and economic assessment

Community-based approaches might increase uptake of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP). We assessed the effects of community-based approaches on IPTp-SP and antenatal care coverage, and barriers and facilitators to implementation in sub-Saharan Africa. We did a systematic review, meta-analysis, meta-ethnography, and economic assessment. We searched the WHO International Clinical Trials Registry Platform, PubMed, the Malaria in Pregnancy Library database, Medline, Global Health and Global Health Archives, and the Cochrane Library for trials, mixed-methods, qualitative, and cost-effectiveness studies of community health worker promotion of antenatal care, IPTp-SP delivery, or both, with no language restrictions, published before March 21, 2024. Information on interventions, number of IPTp-SP doses, antenatal care visits, and barriers and facilitators were extracted. We did a meta-analysis (random effects) comparing effects on two or more or three or more IPTp-SP doses and one or more or four or more antenatal care visits. We followed Noblit and Hare's method of meta-ethnography to synthesise qualitative findings, using reciprocal translation and line-of-argument synthesis. We developed a theory for increased community IPTp-SP uptake. We also summarised cost and cost-effectiveness studies. This study is registered with PROSPERO, CRD42022364114. Of 4753 records screened, we included 23 (0·5%) reporting on 15 studies. Community health worker involvement was associated with an increase in two or more IPTp-SP doses (pooled risk ratio 1·48, [95% CI 1·24-1·75]; 12 sub-studies; I2 94·7%) and three or more IPTp-SP doses (1·73 [1·19-2·50]; ten sub-studies, I2 97·5%), with no decrease in four or more antenatal care visits (1·17 [1·00-1·36]; 13 sub-studies; I2 90·3%). Cluster-randomised controlled trials showed a lower increase in coverage of three or more IPTp-SP doses (1·08 [1·00-1·16]; I2 0·0%; six studies) compared with before-and-after studies (2·86 [1·29-6·33]; I2 98·9%; four studies; subgroup analysis p=0·019). Barriers to community health worker delivery of IPTp-SP included women's fear of side-effects, lack of knowledge, lack of trust in community health workers, and sociocultural factors. Community sensitisation, engagement of husbands, pre-established community health worker networks, and trained and supported community health workers facilitated IPTp-SP delivery by community health workers. Incremental cost-effectiveness ratios ranged from $1·1 to $543 per disability-adjusted life-year averted. Community-based approaches increased IPTp-SP coverage and might have a positive effect on the number of antenatal care visits in addition to being cost-effective, although we found high heterogeneity among studies. Community sensitisation and engagement in addition to established, trained, and supported community health workers can facilitate acceptability, delivery, and uptake of IPTp-SP delivered by community health workers. EDCTP-2 supported by the European Union. For the French translation of the abstract see Supplementary Materials section.

Determinants of the optimal uptake of sulfadoxine–pyrimethamine doses for intermittent treatment of malaria in pregnancy in urban Nigeria

Malaria is a leading cause of maternal and child mortality in urban Nigeria. Intermittent preventive treatment with sulfadoxine–pyrimethamine (IPTp–SP) during pregnancy can prevent malaria but uptake is suboptimal. This cross-sectional study analyzed secondary data on 1159 urban Nigerian women from the 2015 Malaria Indicator Survey using descriptive statistics and logistic regression. The primary outcome was optimal IPTp–SP uptake (≥ 3 doses). 67% of women took any SP during pregnancy but only 39% took ≥ 3 IPTp–SP doses as recommended. Region and wealth index significantly predicted optimal IPTp–SP uptake while education did not. Women from lower-income regions in the urban areas were less likely to receive optimal IPTp–SP. Strategies to increase IPTp–SP uptake in urban Nigeria should target low-income regions and women of lower socioeconomic status. Logistic regression identified actionable factors for improving antenatal malaria prevention. Optimal IPTp–SP uptake remains suboptimal across urban Nigeria, threatening maternal and child health.

Prevalence of mutations associated with artemisinin partial resistance and sulfadoxine–pyrimethamine resistance in 13 regions in Tanzania in 2021: a cross-sectional survey

The emergence of the artemisinin partial resistance (ART-R) mutation in the Plasmodium falciparum kelch13 gene (k13), Arg561His, in Rwanda and the regional presence of polymorphisms affecting sulfadoxine-pyrimethamine have raised concern in neighbouring Tanzania. The goal of this study was to assess the status of antimalarial resistance in Tanzania, with a focus on the border with Rwanda, to understand the distribution of the Arg561His mutation, partner drug resistance, and resistance to chemoprevention drugs. In this cross-sectional survey, capillary dried blood spots were collected from malaria positive asymptomatic individuals in the community and symptomatic individuals in health facilities aged 6months and older, in 13regions of mainland Tanzania from Jan 31to June 26, 2021. Exclusion criteria included residence of the areas other than the target sites, presenting to the health facility for care and treatment of conditions other than malaria, and not providing informed consent. Samples were assessed for antimalarial resistance polymorphisms and genetic relatedness using molecular inversion probes targeting Pfalciparum and short-read whole-genome sequencing. The primary outcome was the prevalence of molecular markers of antimalarial resistance at the region level, as well as at the district level in Kagera, a region in the northwest of the country at the border with Rwanda. 6855 (88·1%) of 7782capillary dried blood spot samples collected were successfully genotyped. The overall prevalence of k13 Arg561His in Kagera was 7·7% (90% CI 6·0-9·4; 50of 649), with the highest prevalence in the districts near the Rwandan border (22·8% [31 of 136] in Karagwe, 14·4% [17 of 118]) in Kyerwa, and 1·4% [two of 144] in Ngara). k13 Arg561His was uncommon in the other regions. Haplotype analysis suggested that some of these parasites are related to isolates collected in Rwanda in 2015, supporting regional spread of Arg561His. However, a novel k13 Arg561His haplotype was observed, potentially indicating a second origin in the region. Other validated k13 resistance polymorphisms (one Arg622Ile and two Ala675Val isolates) were also identified. Aregion of prevalent dihydrofolate reductase Ile164Leu mutation, associated with sulfadoxine-pyrimethamine resistance, was also identified in Kagera (15·2% [12·6-17·8%]; 80of 526). The mutant crt Lys76Thr mutation, associated with chloroquine and amodiaquine resistance, was uncommon, occurring only in 75of 2861genotyped isolates, whereases the wild-type mdr1 Asn86Tyr allele, associated with reduced sensitivity to lumefantrine, was found in 99·7% (3819 of 3830) of samples countrywide. These findings show that the k13 Arg561His mutation is common in northwest Tanzania and that multiple emergences of ART-R, similar as to what was seen in southeast Asia, have occurred. Mutations associated with high levels of sulfadoxine-pyrimethamine resistance are common. These results raise concerns about the long-term efficacy of artemisinin and chemoprevention antimalarials in the region. Understanding how multiple emergences interact with drivers of regional spread is essential for combating ART-R in Africa. This study was funded by the Bill & Melinda Gates Foundation and the National Institutes of Health.

Hyperimmune malarial splenomegaly in a malaria-endemic area of southwest Burkina Faso: case of Bobo-Dioulasso

IntroductionHyperreactive malarial splenomegaly (HMS) is one of the main causes of massive splenomegaly in malaria-endemic zones. Diagnosis is often challenging in Bobo-Dioulasso. This study aimed to describe the clinical and socio-demographic profile, and the reasons for delay in the diagnosis of HMS cases recorded in the Medicine and Medical Specialties wards of Souro Sanou Teaching hospital.MethodsA retrospective descriptive study was conducted from August 2022 by focusing on HMS cases diagnosed in the Infectious Diseases and Clinical Hematology wards of Souro Sanou Teaching Hospital.ResultsOverall, 65 patients met our inclusion criteria over the 12-year period. Burkinabe nationals and have been residing in Burkina Faso since their birth. 79% (79%) of the patients were seen for medical consultation with the reason for consultation being a voluminous mass in the left hypochondrium. Indigence, self-medication, and lack of information were essential elements in late diagnosis of HMS in Bobo-Dioulasso. All patients were treated with a single tablet of Artemether (80 mg) and Lumefantrine (480 mg) in the morning and evening for 3 days, followed by sulfadoxine–pyrimethamine per week. Nine months later, patients were clinically asymptomatic.ConclusionThis study provides a database on hyperreactive malarial splenomegaly (HMS) in the south-west region of Burkina Faso. Rapid and accurate diagnosis of the disease and appropriate use of effective antimalarial drugs would significantly reduce the burden of HMS in Sub-Saharan African countries.

Close Proximity to Mining Is Associated with Increased Prevalence of the Drug Resistance-Associated Mutation dhps540E in Eastern Democratic Republic of the Congo.

Increasing sulfadoxine-pyrimethamine (SP) resistance in the Democratic Republic of the Congo (DRC) has threatened its use for prevention of malaria in one of the most malarious countries in the world. Using geographic information on mining operations in the DRC and genetic data on SP drug resistance markers from the 2013-2014 Demographic and Health Surveys, we evaluated associations between close residence to mining and the presence of mutations conferring resistance to sulfadoxine. Close residential proximity to mining was associated with increased prevalence odds ratio (POR) of the dhps540E mutation (POR: 2.11, 95% uncertainty interval: 1.15-3.96) with adjustments for confounding variables and space. Our findings indicate that exposure to mining is associated with increased presence of an antimalarial drug resistance haplotype that threatens effective use of SP for vulnerable populations. Areas actively engaged in mining could be considered for interventions to reduce the spread of emerging drug resistance in the DRC.

Plasmodium falciparum infection status in children less than 10 years old under seasonal malaria chemoprevention and risk of clinical malaria in the Koulikoro health district, Mali.

Seasonal malaria chemoprevention (SMC) with Sulfadoxine pyrimethamine plus amodiaquine (SP + AQ) consist of a monthly administration of therapeutic dose to children under five years of age during the high risk of malaria in area where malaria is highly seasonal. According to SMC recommendation, both non-infected and asymptomatic Plasmodium falciparum infected children will receive similar treatment. The gap in our knowledge is how the effect of asymptomatic infection on the efficacy of SMC in preventing clinical malaria over a four-week period. Thus, this study aimed to assess the risk of clinical malaria and its association with children's infection status when SMC treatment is given. The study was carried out in the Koulikoro health district in Mali and concerned children under 10 years of age. A total of 726 and 1452 children were randomly selected and followed over the SMC campaign in the years 2019 and 2020 respectively. Prevalence of asymptomatic P. falciparum infection was determined each round by microscopy before SMC drugs intake. Children were passively followed over a four-week period to determine incidence of clinical malaria. R-Studio software was used for analysis. The risk of clinical malaria by infection status was estimated using a logistic regression. A Kaplan-Meier curve was used to determine the survival time between infected and uninfected children. The Pearson Chi-square test was used to compare proportions with the significant level at p< 0.05. The average prevalence of asymptomatic infection was 11.0% both years, and it was higher among children aged 5 to 9 years old in 2019 (p<0.001) and 2020 (p=0.016). The risk of clinical malaria was significantly higher among asymptomatic infected children 2019: (RR=3.05, CI [2.04-4.72]) and 2020 (RR=1.43, CI [1.04-1.97]) transmission seasons. Likewise, the time of the first malaria occurrence was statistically lower among infected children regardless the year (p<0.001 in 2019 and p=0.01 in 2020). Results show a high risk of clinical malaria in asymptomatic infected children during SMC delivery. Screening for P. falciparum infection before the SMC treatment could significantly enhance the impact of the strategy on malaria morbidity in endemic areas.

Two decades of molecular surveillance in Senegal reveal rapid changes in known drug resistance mutations over time

BackgroundDrug resistance in Plasmodium falciparum is a major threat to malaria control efforts. Pathogen genomic surveillance could be invaluable for monitoring current and emerging parasite drug resistance.MethodsData from two decades (2000–2020) of continuous molecular surveillance of P. falciparum parasites from Senegal were retrospectively examined to assess historical changes in malaria drug resistance mutations. Several known drug resistance markers and their surrounding haplotypes were profiled using a combination of single nucleotide polymorphism (SNP) molecular surveillance and whole genome sequence based population genomics.ResultsThis dataset was used to track temporal changes in drug resistance markers whose timing correspond to historically significant events such as the withdrawal of chloroquine (CQ) and the introduction of sulfadoxine-pyrimethamine (SP) in 2003. Changes in the mutation frequency at Pfcrt K76T and Pfdhps A437G coinciding with the 2014 introduction of seasonal malaria chemoprevention (SMC) in Senegal were observed. In 2014, the frequency of Pfcrt K76T increased while the frequency of Pfdhps A437G declined. Haplotype-based analyses of Pfcrt K76T showed that this rapid increase was due to a recent selective sweep that started after 2014.Discussion (Conclusion)The rapid increase in Pfcrt K76T is troubling and could be a sign of emerging amodiaquine (AQ) resistance in Senegal. Emerging AQ resistance may threaten the future clinical efficacy of artesunate-amodiaquine (ASAQ) and AQ-dependent SMC chemoprevention. These results highlight the potential of molecular surveillance for detecting rapid changes in parasite populations and stress the need to monitor the effectiveness of AQ as a partner drug for artemisinin-based combination therapy (ACT) and for chemoprevention.

Seasonal malaria chemoprevention and the spread of Plasmodium falciparum quintuple-mutant parasites resistant to sulfadoxine–pyrimethamine: a modelling study

Seasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine plus amodiaquine prevents millions of clinical malaria cases in children younger than 5years in Africa's Sahel region. However, Plasmodium falciparum parasites partially resistant to sulfadoxine-pyrimethamine (with quintuple mutations) potentially threaten the protective effectiveness of SMC. We evaluated the spread of quintuple-mutant parasites and the clinical consequences. We used an individual-based malaria transmission model with explicit parasite dynamics and drug pharmacological models to identify and quantify the influence of factors driving quintuple-mutant spread and predict the time needed for the mutant to spread from 1% to 50% of inoculations for several SMC deployment strategies. We estimated the impact of this spread on SMC effectiveness against clinical malaria. Higher transmission intensity, SMC coverage, and expanded age range of chemoprevention promoted mutant spread. When SMC was implemented in a high-transmission setting (40% parasite prevalence in children aged 2-10years) with four monthly cycles to children aged 3months to 5years (with 95% initial coverage declining each cycle), the quintuple mutant required 53·1years (95% CI 50·5-56·0) to spread from 1% to 50% of inoculations. This time increased in lower-transmission settings and reduced by half when SMC was extended to children aged 3months to 10years, or reduced by 10-13years when an additional monthly cycle of SMC was deployed. For the same setting, the effective reduction in clinical cases in children receiving SMC was 79·0% (95%CI 77·8-80·8) and 60·4% (58·6-62·3) during the months of SMC implementation when the quintuple mutant was absent or fixed in the population, respectively. SMC with sulfadoxine-pyrimethamine plus amodiaquine leads to a relatively slow spread of sulfadoxine-pyrimethamine-resistant quintuple mutants and remains effective at preventing clinical malaria despite the mutant spread. SMC with sulfadoxine-pyrimethamine plus amodiaquine should be considered in seasonal settings where this mutant is already prevalent. Swiss National Science Foundation and Marie Curie Individual Fellowship.

Impact of Sulfadoxine-Pyrimethamine and Dihydroartemisinin-Piperaquine as Intermittent Preventive Treatment in Pregnancy on Stool Antimicrobial Resistance Gene Abundance.

Increasing antimicrobial resistance (AMR) is a global public health emergency. Although chemoprevention has improved malaria-related pregnancy outcomes, the downstream effects on AMR have not been characterized. We compared the abundance of 10 AMR genes in stool samples from pregnant women receiving sulfadoxine-pyrimethamine (SP) as intermittent preventive treatment against malaria in pregnancy (IPTp) to that in samples from women receiving dihydroartemisinin-piperaquine (DP) for IPTp. All participants had at least one AMR gene at baseline. Mean quantities of the antifolate gene dfrA17 were increased after two or more doses of SP (mean difference = 1.6, 95% CI: 0.4-2.7, P = 0.008). Antimicrobial resistance gene abundance tended to increase from baseline in SP recipients compared with a downward trend in the DP group. Overall, IPTp-SP had minimal effects on the abundance of antifolate resistance genes (except for dfrA17), potentially owing to a high starting prevalence. However, the trend toward increasing AMR in SP recipients warrants further studies.

Plasmodium falciparum dhps and dhfr markers of resistance to sulfadoxine–pyrimethamine five years (2016–2020) after the implementation of seasonal malaria chemoprevention in Cameroon

Background Antimalarial drug resistance is a major challenge in the fight against malaria. Cameroon implemented seasonal malaria chemoprevention (SMC) with sulfadoxine–pyrimethamine and amodiaquine (SPAQ) to over 1.5 million children aged 3–59 months from 2016, raising concerns whether drug pressure may lead to a selection of known parasite resistance mutations. This study aimed at assessing the profiles of plasmodium falciparum dihydrofolate reductase (DHFR) and plasmodium falciparum dihydropteroate synthase (DHPS) gene mutations that encode enzyme targeting SP before and 5 years after the introduction of SMC in the northern part of Cameroon. Methods Dried blood spots were prepared from symptomatic P. falciparum-positive children prior to SPAQ administration in 2016 and after the SMC round of 2020. DNA was extracted using the Chelex-100 method, and dhfr and dhps mutations were determined after a nested polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) technique and agarose gel electrophoresis. Results 405 children with acute uncomplicated malaria were recruited. Of 405 samples, 201/405 (49.63%) were collected in 2016 and 204/405 (50.37%) were collected in 2020. High levels of mutant alleles S108N, C59R, N51I of dhfr were obtained both in 2016 and 2020 (174 (100%), 166 (95.4%), 131 (75.3%)); (140 (99.4%), 131 (92.2%), 114 (80.3%)) while the frequency of dhps mutant alleles in the A437G and K540E loci stood at 93 (51.9%) and 6 (3.4%) in 2016 and 73 (52.5%) and 4 (2.8%) in 2020, respectively. The quintuple resistant haplotype IRNGE was found in two (1.1%) and one (0.7%) in 2016 and 2020, respectively. No significant difference was observed in the frequency of the studied mutations between the two time points, although we noted a rise in the resistance conferring haplotype IRNG in 2020. Conclusions Continuous monitoring is recommended to preempt the widespread occurrence of high-grade resistance bearing parasites in the northern regions of Cameroon.