Multilateral Initiative on Malaria (MIM) Pan-African Malaria Conference – 2024: Day 4

MESA Correspondents bring you cutting-edge coverage from the MIM 2024 Conference “Grassroots Mobilization to End Malaria: Invest, Innovate & Integrate”.

Plenary Session 8 – Immunology and Pathogenesis

Faith Osier (Imperial College London, United Kingdom) discussed immunity mechanisms against Plasmodium falciparum malaria, highlighting the persistence of resistance threats despite the development of two vaccines. Immunity acquisition varies by age (infants appear to acquire immunity faster than older children, but have a higher risk of developing severe forms of malaria and anemia), with asymptomatic cases being more common in high-prevalence areas. Immunoglobulin G (IgG) antibodies from individuals with previous malaria exposure confer a certain degree of immunity. The study on mechanisms of immunity against Plasmodium falciparum focused on the role of merozoite antigens in immunity, utilizing volunteer malaria infections to analyze parasite dynamics. Volunteers were selected based on malaria exposure, with some exhibiting exponential parasite growth, others clearing parasites without symptoms, and some experiencing self-clearance. Cytophilic IgG1 and IgG3 were notably prominent, indicating their significance in protection. Furthermore, IgG Fc function is strongly correlated with protection, underscoring the potential for merozoite antigens in vaccine development, though further assessment is required to identify crucial antigens.

Lars Hviid (University of Copenhagen, Denmark) presented on IgG targeting P. falciparum-infected erythrocytes beginning with an explanation of the parasite’s life cycle and a discussion on natural and acquired immunities. He emphasized the differences between natural and vaccine-induced immunity concerning antigens found in infected erythrocytes (IE,) including differences in target epitopes (complex vs. linear) and effector functions, such as post-translational modifications like Fc-afucosylation. Additionally, he underscored the differentiation between neutralization and opsonization in immune responses. Hviid also advocated for prioritizing basic research and suggested that malaria vaccine development should be guided by studies of natural immunity, notwithstanding current successes in vaccine development.

Symposium 54 – Leveraging genotyping for therapeutic efficacy studies in malaria endemic countries: towards a standardized approach from next generation molecular techniques to data analysis

Aurel Holzschuh (Swiss Tropical and Public Health Institute – SwissTPH, Switzerland) compared different techniques to distinguish recrudescence infections from new infections in antimalarial drug efficacy trials. The genotyping methods included fast capillary electrophoresis (QIAxcel), high-resolution capillary electrophoresis (ABI3730XL), high-resolution melting analysis (Quantstudio 5), targeted amplicon deep sequencing (Illumina Miseq) and nanopore amplicon sequencing (AMPSeq). Four P. falciparum lab-strains (3D7, K1, HB3, FCB1) were used to mimic patient samples and were assessed by the same operator at different weeks. The AMPSeq and high-resolution capillary electrophoresis showed the highest sensitivity and genetic diversity in detecting minority clones and were very robust. The markers used by the AMPSeq were the most consistent in distinguishing recrudescence from new infection. The nanopore technologies provided fast PCR-corrected estimates of drug failures at a low cost and since it is portable they could become an effective alternative genotyping tool in sites with minimal laboratory infrastructures. The nanopore technologies provided fast PCR-corrected estimates of drug failures at a low cost and, since it is portable, they could become an effective alternative genotyping tool in sites with minimal laboratory infrastructures. 

Marko Bajic (Centers for Disease Control and Prevention – CDC, United States) presented laboratory considerations for molecular correction using targeted amplicon deep sequencing. Overall sequencing involves several techniques from sample collection, DNA extraction, genomic targeting and amplification, library preparation and next-generation sequencing.  One of the metrics upon which the choice of a specific sequencer depended was the number of desired reads. Bajic highlighted the importance of considering targeting amplicons for molecular correction since it helps in differentiating between single nucleotide polymorphism (SNPs) and haplotypes; and also the importance of designing shorter amplicons with sufficient sites of diversity. This study showed that next-generation sequencing (NGS) based molecular correction defines amplicon capability, identifies the right targets, communicates mutation rates and ensures this approach can be utilized.

Sam Jones (Liverpool School of Tropical Medicine – LSTM, United Kingdom) presented a study on matching algorithms and simulations to distinguish recrudescence infections from reinfections. He emphasized the necessity for algorithms due to the imperfections in genotyping methods. Jones highlighted two main algorithms: i) Match counting algorithms, widely used since the introduction of molecular correction, ii) A Bayesian algorithm published in 2015 for microsatellites, with ongoing work to expand it for various alleles such as msp-1 and msp-2. He described the simulation environment and how it aided in distinguishing true recrudescence based on the density of alleles, with expert knowledge being incorporated to quantify the detection of alleles. Jones noted that different algorithms applied to the same field data yield varying percentages of recrudescence/reinfection, affecting efficacy assessments. He concluded that match count simulations demonstrate a high ability to detect minority clones, enabling accurate classification even in a high multiplicity of infection (MOI)/force of infection (FOI) scenarios.

Monica Golumbeanu (Swiss Tropical and Public Health Institute – SwissTPH, Switzerland) discussed the considerations involved in analyzing genotyping data for molecular correction in malaria drug trials. She outlined the key steps for molecular correction, including the selection of markers, genotyping experiments, data analysis, extraction of genotypes, and classification of infections. Golumbeanu emphasized the attributes of good markers for molecular correction, such as high allelic density and low allelic frequencies. Additionally, she highlighted several microsatellites commonly used in various studies and mentioned the availability of several pipelines for identifying haplotypes. Golumbeanu explained an automated algorithm for identifying alleles and described the process of identifying haplotypes from amplicon sequencing data, which involves removing primer sequences from samples, aligning reads to a reference genome, and identifying single nucleotide polymorphism (SNPs). She concluded by noting that different markers and techniques may yield different results, emphasizing the importance of careful consideration in data analysis.

Sara Cantoreggi (Swiss Tropical and Public Health Institute – SwissTPH, Switzerland) discussed the assessment of various techniques and markers to distinguish recrudescence from new infections in a therapeutic efficacy study conducted in Rwanda. She explained the Rwanda WHO therapeutic efficacy studies (TES) conducted in 2018 at three sentinel sites in Rwanda, where genotyping was performed. Cantoreggi aimed to reanalyze the samples, examine the genetic diversity of genetic markers, conduct analyses with different marker combinations and algorithms, and compare the results to those obtained previously by Rwanda Biomedical Centre/Centers for Disease Control and Prevention Rwanda. She analyzed samples for length polymorphism and single nucleotide polymorphism (SNP) richness and performed a recrudescence versus reinfection analysis. Cantoreggi concluded that the results were consistent with the WHO algorithm based on marker combinations. She identified eight recrudescences which did not originate from the same eight sample pairs. Discordant cases were attributed to high allelic frequency and low sensitivity in detecting minority clones.

Symposium 56 – Evidence for Strategies to Address Challenges to Malaria Elimination in African Settings

Japhet Matoba (Macha Research Trust, Zambia) discussed the general challenges in eliminating malaria across Africa. Matoba highlighted the rise in the global malaria burden since 2022. Ten countries have successfully eliminated malaria globally since 2016, thanks mainly to robust healthcare systems equipped with targeted vector control, decentralized surveillance, early case detection, effective diagnosis and treatment, and community-based workforce engagement. The WHO recommends tools and innovations for malaria elimination, including chemoprevention and targeted surveillance to prevent outbreaks and re-establishment among pre-elimination countries. However, in Africa, challenges persist due to low transmission near high-intensity areas, infrastructure variations in surveillance, and unknown impacts of interventions. While new tools are necessary, innovative use of current WHO-approved methods like chemoprevention and targeted surveillance can help achieve elimination goals. 

Safia Mohamed Ali (National Malaria Control Programme – NMCP, Tanzania) discussed the rise in malaria cases in 2023. Zanzibar had made good progress in fighting malaria over 15 years, bringing overall cases below 1%. However, in 2023, there was a big increase, with over 19,174 cases, mainly acquired locally. This rise, especially in the west urban region of Unguja island, one of the islands of Zanzibar archipelago, affected mostly males aged 15-45, including students, builders, security guards, tourists, and bodaboda drivers. Challenges for malaria control like climate change, different mosquito types, poor sanitation, and low bed net use were highlighted. Zanzibar is responding to those challenges with different strategies indoor residual spraying, mass drug administration, reactive case detection, and health promotion focused on environmental sanitation. To conclude, she stressed the need for multi-sectoral engagement to catalyze resource mobilization for sustained malaria control in the country.

Davis Mumbengegwi (University of Namibia, Namibia) presented on targeted effective malaria interventions in low transmission settings, focusing on reactive focal mass drug administration (RFMDA) and reactive focal vector control (RAVC) in Namibia. Despite Namibia’s heterogeneous malaria distribution, primarily in the northern Zambezi region, where 85% of the burden lies in the northeast, the country initially set a goal for elimination by 2022,  later revised to 2028. Malaria diagnosis is an important aspect of malaria control which relies on rapid diagnostic tests (RDTs) and microscopy, and is facing challenges like low parasitemia and asymptomatic cases. The study evaluated the feasibility and effectiveness of RFMDA and RAVC, comparing them with reactive case detection (RACD). Results showed a 46% reduction in incidence with RFMDA, 50% with RAVC, and 72% reduction when they were combined. Safety assessments revealed few adverse events, indicating RFMDA and RAVC as safe, acceptable, and efficacious interventions for malaria control in Namibia’s low transmission settings. He recommended future studies with longer implementation and follow-up periods to better assess contributions made by each of the two interventions.

Japhet Chiwaula (National Malaria Elimination Center, Zambia) presented a malaria case investigation using the 1-3-7 approach in Choma district, Southern Zambia, aligning with the national elimination strategy to achieve equitable access to quality health services. Their vision was a malaria-free Zambia, aiming to eliminate local malaria infections by 2021 and to prevent reintroduction post-elimination. The 1-3-7 approach involves reporting passive cases on day one, classifying cases by travel history on day three, and conducting focus investigations on day seven for targeted interventions. Effectiveness and implementation were assessed through zonal randomized studies and mixed methods, respectively. Results showed decreased incidence in 1-3-7 implementation areas, improved community service delivery, and high acceptability among respondents, although challenges with network coverage were common. Community health workers reported enhanced visibility and increased community healthcare-seeking behavior due to the 1-3-7 approach, indicating its positive impact on malaria control efforts in the region.

Chishala Lukwesa Siame (Southern Africa Development Community – SADC, Botswana) presented a collaborative approach to address equity barriers among targeted cross-border populations in the elimination 8 (E8) region. E8 comprises eight countries (Botswana, Eswatini, Namibia, South Africa, Angola, Mozambique, Zambia, and Zimbabwe) working across borders to eliminate malaria in southern Africa by 2030. The objectives include coordinating and engaging countries and stakeholders, advocating for sustained commitment and resources, and harmonizing systems for malaria elimination. A regional equity assessment using the malaria matchbox assessment toolkit was conducted due to high migration levels and migrant populations’ disconnection from health services. The methodology involved desk reviews, focused group discussions with mobile migrant populations (MMPs), and key informant interviews. Findings identified practical, cultural, gender-related, and service-related barriers. The diverse characteristics of MMPs require collaborative efforts to enhance access to information, transportation, and men’s engagement, and empower community health workers. She stated that a regional community engagement strategy was developed to integrate MMPs into regional strategies and improve access to products and services, highlighting a multi-stakeholder approach.

Scientific Session 27 – Drug Resistance 2

Brenda Wanjiru Muriithi (Kenya Medical Research Institute – KEMRI, Kenya) reported a study that was based on assessing the stability of the amodiaquine, lumefantrine, and piperaquine-resistant Plasmodium berghei parasites using a standard 4-day suppression test and identifying nonsynonymous mutations in selected transporters associated with the drugs. Sequencing analysis of the amplified MIT2 fragment revealed a deletion mutation in amodiaquine resistant parasites suggesting that continued amodiaquine pressure induces a stop codon at position 433 in MIT2 protein Plasmodium berghei ANKA. Also, the truncation of the MIT2 protein led to the loss of ligand binding residues at positions 448, 451, and 452 suggesting a loss of function.

Tarama Wendlamita Casimire (National Center for Research and Training on Malaria – CNRFP, Burkina Faso) investigated antimalarial resistance molecular markers of artemether-lumefantrine (AL), dihydroartemisinin-piperaquine (DP), or artesunate-pyronaridine (ASPY) in children aged 6 months to 12 years. The study treated and followed up patients for 28 or 42 days across three health districts with different malaria transmission, focusing on genes linked to drug susceptibility. No significant artemisinin resistance mutations were found, but a minor (1%) pfk13 mutation (A578S) was observed across all sites. The pfmdr1 Y184F mutation, associated with lumefantrine resistance, was prevalent, though with low occurrence of mutations linked to sulfadoxine-pyrimethamine (SP) resistance. Overall, the findings suggest the continued efficacy of artemisinin derivatives and no high level resistance to SP in Burkina Faso. Casimire recommended continuous routine monitoring of antimalarial resistance, including molecular surveillance.

Colin J. Sutherland (London School of Hygiene and Tropical Medicine – LSHTM, United Kingdom) reported a study that recorded evidence of change in the efficacy against African Plasmodium falciparum isolates. They measured in vitro susceptibility to dihydroartemisinin (DHA) and lumefantrine in contemporary P. falciparum and established an ongoing pipeline for monitoring parasite phenotypes and genotypes from east, west, and southern Africa. Since 2012, results from parasite isolates indicate reduced susceptibility to DHA, lumefantrine, or both. Genetic analyses highlight specific loci (pfk13, pfubp1, pfcrt and pfap2mu), indicating adaptation mechanisms unique to African malaria ecology. These findings indicate that parasites with reduced susceptibility exhibit distinct genetic profiles, unlike those responding to artesunate-mefloquine and DHA-piperaquine use. Sutherland proposed that laboratory researchers should take action in response to the early evidence of decreased effectiveness of lumefantrine.

Sarah Volkman (Harvard T.H. Chan School of Public Health and Broad Institute, United States) presented findings from a study in Senegal that evaluated drug resistance in Plasmodium falciparum through genetic markers and selective sweeps, using whole-genome sequence data from samples collected over two decades. Results show sharp changes in Pfcrt-K76T and Pfdhps-A437G frequencies with the Pfdhfr triple + Pfdhps A437G parasite is more fit than the wild-type parasite and equally fit compared to the Pfdhfr triple mutant. Molecular surveillance in Senegal highlights notable shifts in well-known drug resistance mutations. Multiple selective sweeps across the genome, including novel loci, indicate parasite adaptation to natural selection. Drug susceptibility tests reveal associations between mutations and phenotypes, suggesting additional resistance factors. Volkman emphasized the necessity of a phenotypic assessment and genetic validation of known and novel mutations in Senegal to assess the impact of drug pressure and identify genetic determinants of drug resistance. 

Jenna Zuromski (Brown University, United States) presented on the first discovery of Plasmodium falciparum Kelch13 (PfK13) gene mutation including R561H in 2024 which has threatened the efficacy of artemisinin combination therapies (ACTs) in Rwanda. Her aim was to obtain DHA resistance phenotypes of malaria isolates in Rwanda and to evaluate sample pooling as an option for high throughput ex vivo ring-stage survival assays (RSA). Surveillance revealed multiple emerging K13 mutations, some with unknown phenotypes like. Rapid in vitro phenotyping, used in the study, aided in assessing artemisinin partial resistance, but parasite culture adaptation delayed identification. The study also involved the implementation of in-country ex vivo RSA on fresh isolates from high mutation frequency sites. Zuromski’s preliminary results show 11.7% survival post DHA pulse, indicating artemisinin resistance. She proposes analyzing DNA/RNA profiles of pooled samples to understand different phenotypes displayed by pooled vs individual samples.

Stephen Orena (Infectious Diseases Research Collaboration, Uganda) presented findings from a comparative study between standard antimalarials in the periods 2016-2020 and 2021-2023 in eastern and northern Uganda. Samples from uncomplicated P. falciparum patients were used for drug susceptibility testing using growth inhibition and ring-stage survival assays to determine the prevalence of validated PfK13 resistance mutation. The results reveal increasing median IC50 values for various antimalarials, particularly lumefantrine. This finding raises concerns about decreased drug susceptibility and jeopardized efficacy of ACTs, urging ongoing assessment and surveillance efforts. This corresponds to an increased susceptibility to chloroquine over time, alongside a rise in the prevalence of K13 mutations, which are validated markers of artemisinin partial resistance. 

Scientific Session 30 – Malaria Genomics 1

Eshetu Molla (Armauer Hansen Research Institute – AHRI, Ethiopia) spoke on the geographical distribution of Plasmodium vivax duffy binding protein (PvDBP) copy number variation in Adama, Arba Minch, Batiu, Dilla, and Gondarzones, Ethiopia. P. vivax uses the PvDBP from a single point mutation in the DARC promoter region. Blood samples were analyzed using microscopy, and qPCR. Parasites were extracted using the magnetic bead extraction method (n=435). There was variation in DARC genotyping and PvDBP copy numbers with 16.6% infection having a single copy, 50.3% having 2-3 copies, and 33.1% having above 3 copies. Also, there was a lower binding affinity of DARC with single copy PvDBP. Parasitemia was linked with different genotyping status although not correlated with PvDBP. He concluded that P. vivax detected in Duffy-negative individuals, had a high prevalence of multi-copy PvDBP, and showed a high rate of Duffy-positive related to observed parasitemia across all regions.

Thomas Katairo (Infectious Disease Research Collaboration, Uganda) discussed the performance of molecular inversion probes on MAD4HateR amplicon sequencing for the detection of Plasmodium falciparum mutations associated with anti-malaria drug resistance. He pointed out that molecular surveillance is germane in malaria control and there is a need for new genotyping tools with high sensitivity such as molecular inversion probes (MIPs). Six strains of the parasite were used, analysis was limited to single nucleotide proteins (SNP) and parasite densities observation. Results revealed that MAD4HateR recovered genotypes at higher parasitemia while MIPs at lower parasitemia. MAD4HateR works better at all parasitemia except at 10 parasites/µl. He concluded that MAD4HateR has superior coverage and is better for parasitemia detection as compared to MIPs. MIPs are easier to design and good for large-scale surveys but are costlier than MAD4HateR.

Jaishree Raman (National Institute for Communicable Diseases, South Africa) discussed unravelling Plasmodium spp. genetic diversity using targeted amplicon deep sequencing to guide elimination interventions in South Africa. The study was conducted in Mpumalanga (MPN) and Kwazulu-Natal (KZU) with routine sample collection (September 2021 and August 2023). Sequencing was done using MAD4HateR for genotyping and complexity of infection (COI) was used to measure diversity. Polyclonal infection was observed in both provinces with a lower and moderate COI in KZN and MPN respectively. There was an observed co-transmission which he suggested may lead to high polyclonal infection and clusters in both KZN and MPN. He concluded that both provinces have a high polyclonality by importation and intra-host relatedness variation.

Nganyewo Nora Nghochuzie (Medical Research Council Unit, The Gambia) presented the genetic variation in P. falciparum invasion ligands and their cognate human receptor variants in malaria cases from The Gambia. Following a targeted approach using some commonly known ligands, some surface genes as well as human receptors, and 16 genes, 288 samples were collected with 23 and 265 severe and mild cases respectively. The samples were collected from 4 health facilities (Basse, Fajikunda, Edward Francis, and Brikama) within the country and were analyzed using a nanopore sequencing technique. This study showed that the continuous arm race between parasite ligands and receptors results in significant diversity in their haplotypes in P. falciparum and the human population. High inter-SNP LD at both P. falciparum genes and human glycophorin B, C, and CR1 genes were observed. CR1 and glycophorin C seem to have important roles in malaria outcomes.

Jane N. Mwangi (Pan African Mosquito Control Association – PAMCA, Kenya) presented the genomic surveillance of Anopheles arabiensis in The Gambia which revealed evidence of increased insecticide resistance in coastal populations. The samples were collected in different areas of the west coast, central, and inland regions of the country in 2019. Out of the 661 samples collected, 314 were An. arabiensis. Population structure analysis was done showing a clear geographical isolation of An. arabiensis from the coast to the others and she noted that it could create a barrier to gene flow. The mosquitoes from the coastal regions were also more resistant to deltamethrin together by having a high single nucleotide polymorphism (SNP) frequency of the L995S and the L995F kdr mutations, and high copy number variation (CNV) compared to the others showing that they are genetically distinct. A novel carboxylesterase gene cluster was also identified, making it important to investigate a potentially new resistance mechanism to organophosphates.

Scientific Session 31 – Chemoprevention 2

Joel D. Bognini (Research Institute of Health Sciences  – IRSS, Burkina Faso & Clinical Research Unit of Nanoro – CRUN, Burkina Faso) discussed on improving intermittent preventive treatment in pregnant (IPTp) women in Mali and Burkina Faso by utilizing the seasonal malaria chemoprevention (SMC) channel in children. The study evaluated IPTp coverage’s feasibility, acceptability, and cost-effectiveness when delivered through antenatal care (ANC) and SMC. In Mali, 780 women and 816 children were enrolled, and in Burkina Faso, 810 women and 295 children were included. IPTp-SP3 coverage in Burkina Faso (71%) was similar to SMC coverage (76%). In Mali, SMC coverage (51%) exceeded IPT-SP3 coverage (28%). An integrated approach could boost IPTp-DP3 coverage in Mali by compensating poor access to IPTp through ANC facilities.

Jean Baptiste B. Yaro (National Center for Research and Training for Malaria – CNRFP, Burkina Faso) talked about understanding and maximizing the community impact of SMC in Burkina Faso. The study was a randomized controlled trial aimed to directly quantify how extending SMC to children under 10 would reduce the human infectious reservoir. It consisted of three study arms comprising 62 clusters of three compounds: Arm 1 served as control-SMC in under 5-year-old children, implemented by the MoH without directly observed treatment (DOT) for the full course of SMC, Arm 2-SMC in under 5-year-old children with DOT for the full course of SMC, Arm 3- SMC in under 10-year-old children, with DOT for the full course of SMC. Results showed a notable reduction of malaria infection in intervention arms compared to the control arm. Extending the age of SMC reduced parasite prevalence in children. Therefore, extending the age of SMC has the potential to significantly impact the malaria transmission reservoir.

Hindewe Edgar William Houndjo (National Malaria Control Programme – NMCP, Benin) presented on advancing malaria elimination through a digitized approach, focusing on the case of the 2023 SMC campaign in Benin. He emphasized that malaria remains the leading cause of cases and deaths in hospitals in Benin, particularly affecting children under the age of 5. NMCP implemented an annual SMC for children under 5 in highly endemic areas, resulting in a reduction in malaria cases. Houndjo highlighted how digitization accelerates the goal of achieving wide coverage by facilitating planning, training, and program implementation. Consequently, Benin is extending the SMC drug administration campaign to nine new health zones by 2024. Implementation will be based on the country’s new policy of community health in all targeted regions. The digitization of the campaign is planned to be fully implemented by the Ministry of Health through its Information Systems Direction.

Abdul Gafaru Mohamed (National Malaria Elimination Program – NMEP, Ghana) discussed the caregiver’s decision to report adverse drug reactions (ADRs) among children receiving SMC in Ghana. Results showed that less than 20% of caregivers whose children experienced ADRs after receiving SMC medication reported the incidents. Factors associated with ADR reporting were awareness, education, residence, and marital status. Mohamed recommended that regular follow-up mechanisms after dosing should be established and strengthened in all intervention districts by the national malaria elimination programs.

Paul Sondo (Research Institute of Health Sciences – IRSS & Clinical Research Unit of Nanoro – CRUN, Burkina Faso) presented on improving the impact of SMC in Burkina Faso. The study was a randomized controlled trial aimed at assessing whether a strategy combining SMC with nutritional supplements (PlumpyDozTM) could improve the protective effect of SMC and determine whether simultaneous screening and treatment of household members of children receiving SMC could improve the impact of SMC intervention. It was found that adding nutritional supplements to SMC significantly increased the impact (reduction in malaria diagnosis by RDT) of SMC for preventing children from malaria and other childhood infections. Screening and treating other household members lead to a significant reduction in the incidence of clinical malaria in children under SMC coverage. Considering these results, Sondo explained that they are planning to implement this combined approach to better improve the impact of SMC intervention.

Scientific Session 38 – Diagnosis and reagent 2

Amidou Diarra (Health Action Research Group – GRAS, Burkina Faso) presented the findings from two external proficiency testing (EPT) programs for the evaluation of microscopic malaria and other blood parasites, with the aim of contributing to evidence-based policy decisions through high-quality research. GRAS is affiliated with two PT institutions: the College of American Parasitology (CAP), which performs proficiency testing, distributes homogeneous material to participants, and compiles results; and the Clinical Laboratory Services (CLS), which conducts surveys, evaluates individual microscopic performance, and grades microscopists. Microscopists were rated on the precision with which they identified species and counted parasites. Parasite numbers were considered acceptable if they fell within 25% of the true counts. After four years of study, the score climbed to 80%, with 100% overall detection of the malaria parasite and 80% for other parasites. These results show that the PT can help to optimize laboratory organization and boost laboratory efficiency.

Casimire Wendlamita Tarama (National Center for Research and Training on Malaria – CNRFP, Burkina Faso) presented the prevalence of histidine-rich protein 2/3 (HRP2/3) gene deletion in Plasmodium falciparum isolates from Burkina Faso, addressing challenges in malaria diagnosis and treatment. Despite reliance on rapid diagnostic tests (RDTs), issues arose due to the deletion of the Pfhrp2/3 genes, leading to false-negative results and inadequate case management. The study, part of a larger project, investigated asymptomatic malaria prevalence using HRP2-RDT in children aged 6 months to 10 years. Laboratory procedures included DNA extraction and sequencing to detect gene deletions. Results revealed a low prevalence of single hrp2 deletion, affecting HRP2-RDT effectiveness. It was pointed out that ongoing monitoring is crucial due to geographic variations in deletion prevalence, emphasizing the need for further research and funding to assess deletion prevalence in symptomatic malaria cases using WHO standards.

Scientific Session 42 – Parasites and systems biology 1

Afia Farrukh (RWTH Aachen University & University Hospital Mainz, Germany) presented the study on the Plasmodium falciparum CCCH zinc finger proteins MD3 and ZNF4, revealing several significant findings concerning their role in the malaria parasite’s reproductive cycle. Their investigation identified MD3 and ZNF4 as crucial regulators of two key processes: male gametocytogenesis (the process by which male gametocytes are produced within the host’s bloodstream) and exflagellation (the critical step in which male gametocytes release microgametes necessary for fertilizing female gametes within the mosquito vector). A pivotal discovery was the formation of complexes between MD3 and ZNF4 suggesting coordinated efforts between these proteins in regulating male gametocytogenesis. Furthermore, the study determined that MD3 and ZNF4 play instrumental roles in controlling exflagellation. Targeting these proteins in future interventions may disrupt the parasite’s ability to reproduce sexually, thus impeding its spread through the mosquito population and ultimately reducing the burden of malaria transmission.

Sherihan Musa (RWTH Aachen University & University Hospital Mainz, Germany) presented an intriguing discovery regarding gene expression during gametocyte development in the parasite’s life cycle. The SET2 histone methyltransferases were found to play a significant role in modifying histone proteins, which are crucial for packaging DNA and regulating gene expression. Investigating how SET2 regulates gene expression linked to cytoskeletal organization during gametocyte development offers insights into the molecular mechanisms governing the formation and function of these structures. This understanding holds the potential for developing new strategies for combating malaria, including targeted interventions aimed at disrupting the parasite’s ability to develop and transmit between hosts.

Daniel Ayo (Infectious Diseases Research Collaboration, Uganda) presented findings on the gametocytes and infectivity among Ugandan malaria patients exhibiting reduced sensitivity to artemisinin, a critical component of artemisinin-based combination therapies (ACTs). The study unveiled a substantial proportion of patients with pfk13-mutant infections, alongside significant prior treatment with artemether-lumefantrine. Gametocyte densities notably elevated in young children, with a tendency towards higher prevalence in pfk13-mutant infections. Common malaria vectors in the study area were identified as Anopheles gambiae and Anopheles funestus. A follow-up study is planned to evaluate whether artemisinin-resistant strains possess a transmission advantage. This will involve clinical trials utilizing various combination therapies and scrutinizing transmission dynamics before, during, and after treatment. The study aims to select 120 individuals with high-density gametocytes and could provide insights into strategies for combating drug-resistant malaria. Understanding gametocyte production and infectivity in artemisinin-resistant patients is pivotal for mitigating transmission dynamics.

Jean Pierre Musabyimana (Aachen University, Germany) elaborated on the role of P. falciparum SET10 (PfSET-10), a protein in P. falciparum in regulating intraerythrocytic replication and parasite transmission during malaria. PfSET-10 functions by modifying histones, which aid in DNA packaging within cells, thereby gene expression. The expression of histones P. falciparum undergoes dynamic changes throughout the parasite’s differentiation process. The study elucidated the role of histone methylation in controlling gene expression in gametocytes. Results indicated that PfSET10 reduces intra-erythrocytic growth without affecting asexual gametocyte development. Furthermore, H3k18 methylation was found to regulate the replication and transmission of the malaria parasite, playing a crucial role in cyto-adhesion rosetting and erythrocytic inversion, as revealed by transcriptomic analysis. Musabyimana concluded by underscoring the disruptive effect of PfSET10 in regulating parasite transmission and suggested further studies to explore its impact on transmission blocking.

Lorenz Hofer’s (Swiss Tropical and Public Health Institute – SwissTPH, Switzerland) presentation focused on the impact of additional blood meals in increasing sporozoite infection in mosquitoes. He stated that additional blood meals accelerate the development of P. falciparum in mosquitoes, resulting in a higher density of infection. The study revealed that additional blood meal increased the likelihood of mosquito’s infectivity with sporozoites and intensified sporozoite infection, although they did not affect genetic diversity, suggesting any selective advantage of specific genotypes. The plasma-conserved membrane protein (CPMP) was used as a marker for sporozoite infection. Hofer concluded by underscoring the importance of blood in developing polyclonal antibodies.

Michael Lintrier Rivere (Indiana University, United States), presenting on behalf of Wes Boland, discussed the significance of the perfusion index (PI), which measures peripheral perfusion using a point-of-care pulse oximeter.  It quantifies the ratio of pulsatile blood flow to static blood in peripheral tissue and serves as an indicator of mortality in severe cases of P. falciparum malaria. The presentation centered on a multi-cohort study involving 600 Ugandans aged between 6 months to 4 years. Measurement of PI in study participants was conducted upon admission and at 6-hour intervals, with a PI considered low if less than 1%. The results indicated a significant association between PI and clinical complications such as shock, seizures, and increased mortality, with lower PI observed in severe malaria cases compared to uncomplicated malaria cases. Rivere concluded by establishing that PI correlates with traditional clinical perfusion measures and serves as a potential predictor of mortality.

Silvia Portugal (Max Planck Institute for Infection Biology, Portugal) discussed single-cell transcriptional profiling of P. falciparum parasites during both dry and wet seasons. Background information was provided on the seasonality of mosquitoes, parasite persistence in asymptomatic carriers, and the association between poor cyto-adhesion of infected erythrocytes and dry season parasite persistence, contrasting with trophozoite circulation in the wet season. The study had a cross-sectional design, with blood samples collected during both seasons. Results indicated that parasites from the dry season exhibited higher blood circulation compared to those causing clinical malaria manifestation during the wet season. Furthermore, cytoadhesion-related differentially expressed genes (DEGs) between stages were consistent across parasites in both seasons.

Scientific Session 43 – Implementation Science  and Health Systems 1

Kristin Banek (University of North Carolina, United States) introduced the tablet-based Malaria Cascade Analysis Tool (MCAT), which assists health workers in identifying treatment gaps and utilizing available data for informed decision-making. The study aimed to assess MCAT’s capacity to enhance the quality of malaria care for children under five in the Democratic Republic of Congo (DRC). Using the Systems Analysis & Improvement Approach (SAIA), which leverages data to improve decision-making within systems, researchers evaluated its effectiveness. Health workers widely embraced  MCAT, citing improved data quality and promising feasibility, although adjustments to usability are deemed necessary. Future steps involve evaluating SAIA malaria’s impact on care and patient outcomes, integrating severe malaria cases into the care cascade, and adapting it for malaria chemoprevention interventions.

David Salandini Odong (Malaria Consortium, Uganda) discussed Uganda’s program to implement seasonal malaria chemotherapy (SMC) in nomadic pastoralist communities in Karomoja, Uganda, in 2022. SMC involves monthly administration of a full malaria treatment course to children under five years during peak transmission periods. The initiative evaluated SMC coverage, treatment adherence, safety, and caregivers’ perceptions through a cross-sectional survey. Data were collected from caregivers five to six weeks post-SMC round, comparing malaria incidence in children under five during high transmission seasons to the previous year. Results showed high SMC coverage and adherence, well-tolerated medication, increased confidence and knowledge among caregivers, and a decrease in malaria cases among children under five during the SMC period.

Mercis Dimene (Ministry of Health, Mozambique) emphasized the necessity to enhance malaria case management due to identified gaps in surveyed health facilities, where only 14% to 52% of malaria cases were properly managed. The National Malaria Control Program (NMCP) introduced a digital supervision and mentorship tool to monitor and reinforce malaria activities, including case management. The primary aim was to assess uncomplicated malaria case management and identify key dashboards for decision-making. Results revealed specific gaps in practices such as inconsistent fever screening, weight assessment, and patient malaria testing. The electronic supervision tool effectively gauged care quality at health facilities, providing insights for targeted clinician training and action plans to enhance decision-making processes at all levels.

Mariana da Silva (National Malaria Control Programme – NMCP, Mozambique) presented on the digitisation of Mozambique’s ITN campaign (2022-2023) and future integration plans by using DHIS2 and DIGIT (tools/modules that contain a set of standard data collection forms, automatically calculated indicators, data visualizations, and thematic dashboards that allow collecting, visualize and interpret data from the activities in line with WHO recommendations). Mozambique, burdened with high malaria rates, successfully digitized its ITN campaign, enhancing transparency and efficiency. Outcomes indicated improved data accuracy and promptness, with 95% of records dispatched within the day and 93% synchronized by 7:00 PM. These data show positive outcomes encompassed improved data timeliness and enhanced supervision. Lessons learned included implementing structured M&E strategies and addressing challenges like incomplete data records.  For the future, Mozambique aims to evaluate platforms, integrate digitisation into other campaigns, and optimize coordination, emphasizing the vision of leveraging digital tools across multiple campaigns to strengthen public health initiatives efficiently.

Arthur Sovi (University of Parakou, Benin) discussed findings from a three-year cluster randomized controlled trial in Benin, examining the effects of dual active ingredient long-lasting insecticidal nets (LLINs) on insecticide resistance in malaria vectors. Adult mosquitoes were collected indoors and outdoors in 60 clusters using human landing catches at baseline and every 3 months for 2 years. The study revealed significant reductions in pyrethroid resistance initially, but resistance intensity resurged over time, particularly in certain trial clusters. Additionally, there were variable impacts on vector fertility and changes in metabolic gene expression levels across different LLIN arms. The results suggest the need for revised deployment strategies of chlorfenapyr-pyrethroid LLINs in high-resistance settings, emphasizing the importance of tailored interventions based on vector species complexity and resistance mechanisms.