fbpx

By Dr. Derick Pasternak, Ambassador, Malaria Science & Research Coordinator, MPI

On 15 February, the WHO published its Updated WHO Guidance for Controlling Vector-Borne Diseases Through Indoor Residual Spraying (https://www.who.int/news/item/15-02-2024-updated-who-guidance-for-controlling-vector-borne-diseases-through-indoor-residual-spraying) “An estimated 80% of the world’s population is at risk of one or more vector-borne diseases. Mosquitoes, flies, bugs and other vectors transmit viruses, parasites and bacteria that infect millions of people globally. They cause deadly and debilitating diseases such as malaria, dengue, Chikungunya, yellow fever, Zika virus disease, leishmaniases and Chagas disease.
“Vector-borne diseases thrive in conditions of poverty, and mortality rates are often disproportionately high in poorer populations. Those who survive can be left permanently disabled or disfigured, compounding their disadvantage. Taken together, these diseases exact an immense toll on economies and restrict both rural and urban development.
“To prevent malaria, WHO recommends 2 vector control interventions for large-scale use: insecticide-treated nets and indoor residual spraying (or IRS). For IRS, insecticides are sprayed inside houses and other buildings where disease-transmitting insects are likely to rest. IRS has been widely used to kill malaria-carrying Anopheles mosquitoes, but it can also kill insects that transmit other diseases.…
“As detailed in the new operational manual on indoor residual spraying (https://www.who.int/ publications/i/item/9789240083998), successful IRS campaigns require a high level of political commitment with dedicated human, logistical and financial resources. Adequate health system capacity is essential to ensure that the spray application is well timed, of good quality and of sufficiently high coverage. The engagement of community leadership and the acceptance of spray operations by local residents are also key to success.”
“The manual identifies 5 basic goals for an IRS campaign:
1. spray coverage: to protect as many individuals as possible in the target area, with particular emphasis on protecting vulnerable groups;
2. spray acceptance: to achieve spraying of a high number of units and structures in the target area;
3. spray progress or efficiency: to ensure that enough houses are sprayed each day to keep the campaign on schedule;
4. spray quality: to ensure that spray operators use the correct procedures and techniques to deposit the right amount of insecticide on all sprayable surfaces; and
5. spray monitoring and evaluation: to monitor spray coverage, acceptance, progress, quality, and, where possible, the efficacy and effectiveness of the campaign, with a view to informing improvements for subsequent campaigns….”
PEER REVIEWED ARTICLES (see notes after citations from non-peer-reviewed publications)
Prevention

Vaccines

Acceptance of the vaccines by parents for their children is a critical element of preventing malaria mortality. Saaka SA & al., Child Malaria Vaccine Uptake in Ghana: Factors Influencing Parents’ Willingness to Allow Vaccination of Their Children Under Five (5) Years, PLoS One. 2024 Jan 19; 19(1):e0296934, https://doi.org/10.1371/journal.pone.0296934 explores the factors that lead parents to accept or reject the use of malaria vaccine for their children age five and below. “Maternal awareness of vaccine … significantly predicted higher likelihood of vaccine uptake. Household wealth was associated with child vaccination as parents in middle-income households … and those in poorest households … recorded higher likelihood of allowing their children to be vaccinated… Knowing that malaria is covered by National Health Insurance … was associated with higher likelihood of allowing child vaccination compared to not knowing. … parents who lived in rural areas … were significantly less likely to allow vaccination of their children compared to those in urban areas.”
The recent endorsement of WHO of the R21/Matrix-M vaccine was undoubtedly influenced by the results of the work of Datoo MS & al. which was just published as Safety and Efficacy of Malaria Vaccine Candidate R21/Matrix-M in African Children: A Multicentre, Double-Blind, Randomised, Phase 3 Trial, Lancet. 2024 Feb 1: S0140-6736(23)02511-4, https://doi.org/10.1016/s0140-6736(23)02511-4. In four sub-Saharan countries 4878 children were studied; 2/3 of whom received the vaccine, 1/3 the control injections. Twelve-month “vaccine efficacy was 75% … at the seasonal sites and 68% … at the standard sites for time to first clinical malaria episode. Similarly, vaccine efficacy against multiple clinical malaria episodes was 75% … at the seasonal sites and 67% … at standard sites. A modest reduction in vaccine efficacy was observed over the first 12 months of follow-up…” The vaccine was well tolerated, with fever (46%) and pain at injection site (18%) the most common side effects; but there were no severe side effects or deaths. Significant attrition along the series must have occurred because the reported denominator of the side effects was barely more than 50% of those who received the first dose of the vaccine. A news release by Oxford University, where much of the vaccine development took place can be reached at https://www.ox.ac.uk/news/2024-02-01-new-phase-3-trial-data-confirm-uniquely-high-efficacy-and-good-safety-profile.
Schmidt N & al. used data from the trial of the R21/Matrix-M vaccine in Burkina Faso to estimate “the cases, malaria deaths, and disability-adjusted life-years (DALYs) averted and cost-effectiveness over a 15-year time horizon across a range of transmission settings in sub-Saharan Africa. Cost-effectiveness was estimated incorporating the cost of vaccine introduction (dose, consumables, and delivery) relative to existing interventions at baseline.” They report in The Public Health Impact and Cost-Effectiveness of the R21/Matrix-M Malaria Vaccine: A Mathematical Modelling Study, Lancet Infect Dis, 2024 Feb 8, https://doi.org/10.1016/S1473-3099(23)00816-2 that “[a]ge-based implementation of a four-dose regimen of R21/Matrix-M vaccine was estimated to avert 181 825 … clinical cases per 100 000 fully vaccinated children in perennial settings and 202 017 … clinical cases per 100 000 fully vaccinated children in seasonal settings. … Under an assumed vaccine dose price of US$3, the incremental cost per clinical case averted was $7 …) in perennial settings and $6 … in seasonal settings and the incremental cost per DALY averted was $34 … in perennial settings and $30 … in seasonal settings…” The authors conclude that substantial benefit is likely to derive from use of the vaccine as recommended. In the same issue, Ngou O, R21/Matrix-M Malaria Vaccine: A Vital Tool in the Arsenal Against Malaria, Not a Silver Bullet, Lancet Infect Dis, 2024 Feb 8, https://doi.org/10.1016/S1473-3099(23)00010-0, state the following: “Although this vaccine represents a substantial advance and could potentially serve as a tool in the fight against malaria, it is important to understand that it will not solve the problem alone … we must emphasise the continued need for integrated strategies, including insecticide-treated nets, indoor residual spraying, prompt diagnosis and effective treatment, seasonal malaria chemoprevention, prevention of malaria in pregnancy, and special attention to robust community engagement.”

The WHO recommended vaccines, RTS,S and R21, “are subunit (SU) vaccines that target a single Plasmodium falciparum (Pf) pre-erythrocytic (PE) sporozoite (spz) surface protein known as circumsporozoite (CS). These vaccines induce humoral immunity but fail to elicit CD8 + T-cell responses sufficient for long-term protection. In contrast, whole-organism (WO) vaccines, such as Radiation Attenuated Sporozoites (RAS), achieved sterile protection but require a series of intravenous doses administered in multiple clinic visits.” They are also extremely difficult to produce and require multiple IV doses for effectiveness. MacMillen Z & al. describe a process by which two different agents (an RNA-based preparation and a whole sporozoite) are administered sequentially within a few days. The results in mice are promising in terms of producing cellular as well as humoral immunity. The paper is Accelerated Prime-and-Trap Vaccine Regimen in Mice Using RepRNA-Based CSP Malaria Vaccine, NPJ Vaccines. 2024 Jan 10; 9(1):12, https://doi.org/10.1038/s41541-023-00799-4.
Radiation attenuated whole sporozoites are also investigated by Watson FN & al. They report in Ultra-Low Volume Intradermal Administration of Radiation-Attenuated Sporozoites with the Glycolipid Adjuvant 7DW8-5 Completely Protects Mice Against Malaria, Sci Rep. 2024 Feb 4; 14(1):2881, https://doi.org/10.1038/s41598-024-53118-9 that ultra-low volumes of the sporozoites and the proper adjuvant combine to provide full protection against malaria in mice. The authors contrast this result against reports of unsuccessful intradermal (ID) inoculation without adjuvant and claim that this method of ID use may be preferable to intravenous injections.
Oduoye MO & al., Unlocking the Potential of Novel RTS, S/AS01, and R21/Matrix-M™ Malaria Vaccines in African Nations, Health Sci Rep. 2024 Jan 4; 7(1):e1797, https://doi.org/10.1002/hsr2.1797 is reported under Campaigns & Policies because it advocates specific vaccination policies.
There is widespread recognition that neither of the two currently WHO-endorsed vaccines is ideal for the control of P. falciparum, because of the need for multiple injections and less than 80% efficacy. Locke E & al. state that “[t]o improve upon the malaria vaccine, RTS,S/AS01, it is essential to standardize preclinical assays to measure the potency of next-generation vaccines against this benchmark” in Establishing RTS,S/AS01 as a Benchmark for Comparison to Next-Generation Malaria Vaccines in a Mouse Model, NPJ Vaccines, 2024 Feb 10; 9(1):29, https://doi.org/10.1038/s41541-024-00819-x. Having developed a mouse model, they claim that “[c]omparison in animal models of CSP {circumsporozoite}-based vaccine candidates to RTS,S/AS01 is now possible under well controlled conditions.”
According to Takashima E & al., “the paucity and limitations of pre-erythrocytic vaccines highlight the need for asexual blood-stage malaria vaccines that prevent disease caused by blood-stage parasites.” However, “[f]ew asexual blood-stage vaccine candidates have reached phase 2 clinical development, and the challenges in terms of their efficacy include antigen polymorphisms and low immunogenicity in humans.” Their review, The Need for Novel Asexual Blood-Stage Malaria Vaccine Candidates for Plasmodium falciparum, Biomolecules. 2024 Jan 12; 14(1):100, https://doi.org/10.3390/biom14010100 summarizes the history and progress of asexual blood-stage malaria vaccine development, highlighting the need for novel candidate vaccine antigens/molecules.
The work on new vaccines does not always succeed in finding a preparation that is effective. Friedman-Klabanoff DJ& al., Recombinant Full-Length Plasmodium falciparum Circumsporozoite Protein-Based Vaccine Adjuvanted with GLA-LSQ: Results of Phase 1 Testing with Malaria Challenge, J Infect Dis. 2024 Feb 8: jiae062, https://doi.org/10.1093/infdis/jiae062 is a report on a preparation that was “safe” but did not result in immunity.
Transmission blocking vaccines (TBVs) do not prevent infection but reduce the likelihood of transmitting malaria from a person to a biting mosquito, thereby diminishing the likelihood of spreading the disease. Its ideal use would be in conjunction (or combination) with a true vaccine. Scaria PV & al., mRNA Vaccines Expressing Malaria Transmission-Blocking Antigens Pfs25 and Pfs230D1 Induce a Functional Immune Response NPJ Vaccines. 2024 Jan 6; 9(1):9, https://doi.org/10.1038/s41541-023-00783-y reports on a study conducted in the mouse model of an mRNA-based transmission blocking vaccine that resulted in “[maintaining] >99% transmission reducing activity through 126 days, the duration of the study, demonstrating the potential of mRNA platform for TBV.”
While much of vaccine research has concentrated on prevention of P. falciparum infection, Ntumngia FB & al.’s paper, Naturally Acquired Antibodies Against Plasmodium vivax Pre-Erythrocytic Stage Vaccine Antigens Inhibit Sporozoite Invasion of Human Hepatocytes in vitro, Sci Rep. 2024 Jan 13; 14(1):1260, https://doi.org/10.1038/s41598-024-51820-2 has relevance in communities such as many in Ethiopia, where P. vivax is frequently found. The authors “evaluated the magnitude and quality of naturally acquired antibody responses to four P. vivax PE antigens: sporozoite surface protein 3 (SSP3), sporozoite protein essential for traversal 1 (SPECT1), cell traversal protein of ookinetes and sporozoites (CelTOS) and CSP in plasma of P. vivax infected patients…” and found that they have vaccine potential of these antigens in protecting against hepatocyte infection…” They also highlight “the need for a multi-valent pre-erythrocytic vaccine to prevent liver stage development of P. vivax sporozoites.”
Vector control and protection from vectors

Wotodjo AN & al. conducted a retrospective study to investigate upsurges of malaria prevalence especially in children and young adults between the ages of 10 and 29. As they report in their paper, Malaria Epidemics Associated with Low Net Use in Preadolescent and Young Adult Population in Dielmo (Senegal), A Malaria Pre-Elimination Area, Parasit Vectors, 2024 Feb 19; 17(1):74, https://doi.org/10.1186/s13071-024-06172-1, they found direct correlation with reduction in impregnated net use at these times.

Based on a “semi-field” condition study “using modeled estimates,” Abong’o B & al. conclude in Insecticide Treated Eaves Screens Provide Additional Marginal Protection Compared to Untreated Eave Screens Under Semi-Field Conditions in Western Kenya, MWJ 2024 Jan, 15:1, https://doi.org/10.5281/zenodo.10567425 that “[e]ave, door and window screening are effective ways of reducing mosquito entry into houses. Additionally, treatment of eave screen material with an effective insecticide further reduces the Anopheles population in and around the screened huts under semi-field conditions and could greatly complement existing vector control efforts.”
Mwalimu CD & al., Dynamics of Malaria Vector Composition and Plasmodium falciparum Infection in Mainland Tanzania: 2017–2021 Data from the National Malaria Vector Entomological Surveillance, Malaria J, 2024 Jan 19, 23:29, https://doi.org/10.1186/s12936-024-04849-7 ia a study of vector prevalence, as part of national surveillance. While the abstract identifies An. arabiensis as the predominant vector, P. falciparum infection rates of the mosquitoes are not mentioned.
Wangrawa DW & al., Distribution and Insecticide Resistance Profile of the Major Malaria Vector Anopheles funestus Group Across the African Continent, Med Vet Entomol. 2024 Feb 2, https://doi.org/10.1111/mve.12706 is a report of the literature on insecticide resistance by Anopheles funestus, which is one fo the main vectors of malaria transmission in Africa. “An. funestus was increasingly resistant to the four classes of insecticides recommended by the World Health Organisation for malaria vector control; however, this varied by country. Insecticide resistance appears to reduce the effectiveness of vector control methods, particularly IRS and ITN. Biochemical resistance due to detoxification enzymes (P450s and glutathione-S-transferases [GSTs]) in An. funestus was widely recorded. However, An. funestus in Africa remains susceptible to other insecticide classes, such as organophosphates and neonicotinoids.”
Zanga J & al. found two species of Plasmodium-spreading mosquitoes in Kinshasa, as they report in Species Composition and Distribution of the Anopheles gambiae Complex Circulating in Kinshasa, GigaByte. 2024 Jan 3; 2024:gigabyte104, https://doi.org/10.46471/gigabyte.104. The species are An. gambiae s.s. and An. coluzii, with the former being the preponderant species. GigaByte claims on its website to be an “open peer review” journal, which this reviewer interprets as containing articles that had not been peer reviewed prior to publication.
“Historically, Anopheles funestus sensu stricto (s.s.) has been the major malaria vector in southern Mozambique, with … species within the Anopheles gambiae species complex playing a minor role in malaria transmission.” Máquina M & al., Multiple Anopheles Species Complicate Downstream Analysis and Decision-Making in a Malaria Pre-Elimination Area in Southern Mozambique, Malaria J, 2024 Jan 18; 23:23, https://doi.org/10.1186/s12936-024-04842-0 describes several more species, three of them members of the Anopheles coustani group, that were identified within a group of 81 specimens collected in a particular region. Identification was both by inspection and by sequencing “at the ribosomal DNA internal transcribed spacer region 2 (ITS2) and/or cytochrome oxidase subunit 1 (CO1) loci towards species determination.” The authors conclude that given these new potential vectors, vector control efforts, including the training of local technical staff, need to be updated.
Nagi SC & al. found a genetic anomaly, namely duplication of a locus in the DNA of Anopheles gambiae, which change has already been noted in Culex pipiens (the vector of West Nile virus) to confer resistance to a recently introduced insecticide. Indeed, as reported in Parallel Evolution in Mosquito Vectors – A Duplicated Esterase Locus is Associated with Resistance to Pirimiphos-Methyl in An. gambiae, bioRxiv. 2024 Feb 1: 2024.02.01.578361, https://doi.org/10.1101/2024.02.01.578361, the authors claim that these genetically different Anopheles mosquitoes are similarly resistant. As noted in previous monthly reports, BioRxiv publishes non-peer reviewed articles.
The problems arising from the invasion of Anopheles stephensi in societies not accustomed to its presence are discussed at length by Emiru T & al. in Evidence for a role of Anopheles stephensi in the spread of drug- and diagnosis-resistant malaria in Africa, Nat Med, 2023 Dec, 29:3203-11, https://doi.org/10.1038/s41591-023-02641-9. In this study of an urban outbreak in Dire Dawa, Ethiopia, “An. stephensi was the only species detected in artificial containers …, of which the majority were metal and plastic barrels and jerrycans, and was the predominant species detected at stream edges …. Adult Anopheles spp. mosquitoes were detected in the majority of examined animal shelters …, water storage tankers…, manholes …, with nearly all identified as An. stephensi.” In this outbreak most of those infected were adult males and all were infected by P. falciparum. Also, many strains carried the gene associated with partial artemisinin resistance and also lacked the genes that code for histidine-rich protein, thereby posing diagnostic challenges.
In the course of searching for efforts to control An. stephensi, this reviewer came across a paper from earlier in 2023. While the paper, Fatima N & al., Biotoxicity Comparison of Bacillus thuringiensis to Control Vector Borne Diseases Against Mosquito Fauna, Saudi J Biol Sci, 2023 Apr, 30(4):103610, https://doi.org/10.1016/j.sjbs.2023.103610 focused on the effects of B. thuringiensis (Bt) on Aedes egypti larvae, the authors also state that “Bt. isolates were utmost noxious to 3rd instar larvae of mosquitoes Aedes aegypti, Anopheles stephensi, and Culex pipiens.” The data in the paper support the statement.
Recognizing that urban environments have very different lighting conditions than rural ones at night, Llergo JL & al. investigated the effect of artificial light on An. stephensi. In their laboratory. Artificial Nighttime Lighting Impacts Plasmodium falciparum Mature Stage V Gametocytes Infectivity in Anopheles stephensi, Malaria J, 2024 Feb 8, 23:42, https://doi.org/10.1186/s12936-024-04866-6 reports that the application of artificial light actually inhibited the development of the infective form of p. falciparum in the mosquito gut. The authors suggest that light may become a preventive factor in combating malaria spread by An. stephensi.

Dicko B & al., Stakeholder Engagement in the Development of Genetically Modified Mosquitoes for Malaria Control in West Africa: Lessons Learned from 10 Years of Target Malaria’s Work in Mali, Front Bioeng Biotechnol. 2024 Jan 5; 11:1286694, https://doi.org/10.3389/fbioe.2023.1286694 is a retrospective of how community resources were recruited and engaged in gene drive research.
Saili K & al., “evaluated the impact of combining house screens with long-lasting insecticidal nets (LLINs) on mosquito host-seeking, resting, and biting behavior. Intervention houses received house screens and LLINs, while control houses received only LLINs.” As reported in House Screening Reduces Exposure to Indoor Host-Seeking and Biting Malaria Vectors: Evidence from Rural South-East Zambia, Trop Med Infect Dis. 2024 Jan 15; 9(1):20, https://doi.org/10.3390/tropicalmed9010020, there were “68% fewer indoor host-seeking Anopheles funestus … and 63% fewer An. arabiensis … in screened houses than unscreened houses. … The estimated indoor [entomological infection rate] in unscreened houses was 2.91 infectious bites/person/six months, higher than that in screened houses (1.88 infectious bites/person/six months)…”
Abossie A & al. Higher Outdoor Mosquito Density and Plasmodium Infection Rates in and Around Malaria Index Case Households in Low Transmission Settings of Ethiopia: Implications for Vector Control, Parasit Vectors. 2024 Feb 6; 17(1):53, https://doi.org/10.1186/s13071-023-06088-2 is classified below, under Epidemiology/Risk factors.
Chemoprophylaxis

Khan J & al. administered seasonal malaria chemoprevention (SMC) including sulfadoxine-pyrimethamine and amodiaquine to 19,000 children under 5 years and the outcome of a sample of 2760 children was compared to a similar number in a county where no SMC was administered. They report in their paper, A Quasi-Experimental Study to Estimate Effectiveness of Seasonal Malaria Chemo-prevention in Aweil South County in Northern Bahr El Ghazal, South Sudan, Malaria J, 2024 Jan 24, 23:33, https://doi.org/10.1186/s12936-024-04853-x, that there were significantly fewer episodes of both unspecified fever and diagnosed malaria among the treated children than in the control group.
Traoré K & al. “report the safety and efficacy of dihydroartemisinin-piperaquine (DHA-PQ) for SMC in school-aged children in Mali” in Randomized Field Trial to Assess the Safety and Efficacy of Dihydroartemisinin-Piperaquine for Seasonal Malaria Chemoprevention in School-Aged Children in Bandiagara, Mali, J Infect Dis. 2024 Jan 12; 229(1):189-197, https://doi.org/10.1093/infdis/jiad387. Their “randomized, controlled trial included 345 participants aged 6-15 years randomized to receive DHA-PQ, sulfadoxine-pyrimethamine plus amodiaquine (SP-AQ), or no chemoprevention…” Both regimens were effective in reducing the incidence of malaria in the children but those receiving DHA-PQ experienced fewer side effects than those who received SP-AQ.
“There are few studies of SMC adverse event surveillance in sub-Saharan Africa, particularly in Burkina Faso, a highly endemic country.” Ouoba J & al.’s main objective was to characterize the adverse drug reactions (ADRs) reported during SMC campaigns in Burkina Faso. Of 1105 “individual case safety reports recorded in … in Burkina Faso from 2014 to 2021 (of a total of over 23 million doses administered), [i]n 38.1% of children, the occurrence of ADRs led to discontinuation of SMC treatment. Vomiting was the most frequently reported adverse drug reaction (48.0%).” The authors also state that among 101 “serious cases, … 23 were preventable.” The French language paper is titled in English (as is the language of the Abstract) as Monitoring of Adverse Drug Reactions During Seasonal Malaria Chemoprevention Campaigns in Children Aged 3–59 Months in Burkina Faso, Santé Publique. 2024 Jan 3; 35(5):121-132, https://doi.org/10.3917/spub.235.0121
“Monitoring and evaluating (M&E) SMC programmes are complex due to the scale, time-sensitive delivery of the programme, and influence of external factors.” de Cola MA & al., From Efficacy to Effectiveness: A Comprehensive Framework for Monitoring, Evaluating and Optimizing Seasonal Malaria Chemoprevention Programmes, Malaria J, 2024 Feb 2, 23:39, https://doi.org/10.1186/s12936-024-04860-y “describes the process followed to develop a comprehensive M&E framework tailored specifically for the SMC context… The Framework was developed through a literature and programme review, and stakeholder dialogues across three implementing countries—Burkina Faso, Chad, and Nigeria… An overall aim and seven programme objectives were developed measured by 70 indicators. The indicators also capture the causal links between the implementation and results of the programme…The framework presented here provides a standardized approach for programme implementers to enhance decision-making for optimal programme performance Framework presented here provides a standardized approach for programme implementers to enhance decision-making for optimal programme performance.”
Similar to other reports, Mwaiswelo R & al. found that artemisinin-based SMC is effective in the Tanzania area they studied. “Before the intervention, malaria prevalence was 13.7% … and 18.2% … in the intervention and control clusters, respectively, …. Malaria prevalence declined to 5.8% … in the intervention clusters after three rounds of DP, and in the control clusters it declined to 9.3% … Unadjusted and adjusted prevalence ratios between the intervention and control arms were 0.42 … and 0.77 … respectively. Their paper, Dihydroartemisinin-Piperaquine Effectiveness for Seasonal Malaria Chemoprevention in Settings with Extended Seasonal Malaria Transmission in Tanzania, Sci Rep. 2024 Jan 25; 14(1):2143, https://doi.org/10.1038/s41598-024-52706-z, does not mention why they did not use the WHO-endorsed SMC regimen.
“The World Health Organization (WHO) has recommended several malaria chemoprevention strategies, some of them for over a decade, and each with documented efficacy and cost effectiveness.” Littman J & al. consider “new insights into the empirical evidence that supports the broader application of chemoprevention and encourages its application as a default strategy for young children living in moderate to high transmission settings” in Making the Most of Malaria Chemoprevention, Malaria J, 2024 Feb 19, 23:51, https://doi.org/10.1186/s12936-024-04867-5.
Please see Xu E & al., Evolution of Spatial Risk of Malaria Infection After a Pragmatic Chemoprevention Program in Response to Severe Flooding in Rural Western Uganda, J Infect Dis. 2024 Jan 12;229(1):173-182, https://doi.org/10.1093/infdis/jiad348 in Epidemiology/Risk Factors
Other
The transmission-blocking agent ivermectin is the subject of Kern C & al., Pharmacokinetics of Ivermectin Metabolites and Their Activity Against Anopheles stephensi Mosquitoes, Malaria J, 2023 Jun 24; 22:194, https://doi.org/10.1186/S12936-023-04624-0. It was not reported earlier, because it is a basic science report from work in the laboratory. However, the results are important in that the authors conclude that “the ivermectin metabolites M1 and M2 contribute to the activity of ivermectin against An. stephensi mosquitoes.”
Diagnosis

General diagnostics

The diagnosis of febrile children is frequently complicated in communities where malaria is prevalent. Shittu O & al., Comorbidity of Malaria and Septicemia in Children Living in Malaria-Endemic Communities in Nigeria, Acta Parasitol. 2024 Jan 13, https://doi.org/10.1007/s11686-023-00781-z addresses this conundrum. They noted the relatively high frequency of bacterial septicemia among children with malaria and attempted “to identify possible overlap between serum cell-reactive proteins (C-rp) and hematological indices as predictors of comorbidity of malaria and septicemia among children attending primary healthcare facilities…” Ultimately, they were unable to demonstrate the diagnostic utility of this test.
Field diagnostics

Mukadi-Kaningu P & al. conducted a “non-random cross-sectional study” in 88 clinical laboratories in Kinshasa, which “focused on cross-checking of blood slides, a questionnaire and checklist according to standardised analytic malaria microscopy procedures.” As reported in their paper, Unravelling the Quality of Malaria Microscopy Across Kinshasa, DR Congo, Malaria World J, 2024, 15:2, https://doi.org/10.5281/zenodo.10630995, “individuals qualified to perform thick blood films (TBF) according to the national malaria control program (NMCP) procedures ranged from 48.6% to 100.0%. Overall cross-checking performance of 167 eligible routine slides was relatively low: 37.7%; 25.8% and 36.5% of correct, acceptable and incorrect responses, respectively…” The authors insist that “laboratories must implement clear and standardised malaria microscopy procedures and need to include more rigorous quality control.”
“Malaria eradication efforts in resource-limited areas require a rapid, economical, and accurate tool for [the detection of] low parasitemia. [Malaria RDT is] most suitable for on-site detection of … Plasmodium falciparum. [However,] deletions of histidine rich protein 2 and 3 genes … compromise the effectiveness of mRDT… [L]oop-mediated isothermal amplification (LAMP)… is a one-step [process] that allows the detection of Plasmodium species in less than an hour.” Nguyen TK & al., Enhancing Malaria Detection in Resource-Limited Areas: A High-Performance Colorimetric LAMP Assay for Plasmodium falciparum Screening, PLoS One. 2024 Feb 9; 19(2):e0298087, https://doi.org/10.1371/journal.pone.0298087 sets out “to enhance the performance of a colorimetric LAMP (cLAMP) for field application … The test result … indicates that the optimal reaction condition for cLAMP was 30 minutes incubation at 65°C, a shorter incubation time compared to previous LAMP detection methods that typically take 45-60 minutes. The limit of detection … was 1,000-fold higher than referencing primers. Under optimal reaction condition, the new primer sets showed … 100% … accuracy on the detection of dried blood spots from Malawi.”
New diagnostic methods

Li J & al. describe an immunoassay for P. falciparum that they claim is more rapid than current tests in Rapid Diagnosis and Prognosis of Malaria Infection Using a Microfluidic Point-Of-Care Immunoassay, Biosens Bioelectron. 2024 Feb 2; 250:116091, https://doi.org/10.1016/j.bios.2024.116091. However, this immunoassay is dependent on the presence of histidine-rich proteins (HRP) 2 and 3, which is the drawback of many of the currently used RDTs, because of the emergence of mutations that alter or delete these proteins.
“Combining the advantages of PCR and LAMP,” Lai MY & al. describe “a new technique, namely PCR-LAMP, for malaria diagnosis. The whole process of DNA amplification can be completed in 35 min. This hybrid amplification technique markedly improved the sensitivity of detection compared to the classic single PCR or LAMP assay alone.” In A Visualized Hybrid PCR-LAMP Assay for the Detection of Human Plasmodium Species, Acta Trop. 2024 Jan 8:107120, https://doi.org/10.1016/j.actatropica.2024.107120, the authors state that “PCR-LAMP poses the potential to be developed as a new malaria molecular diagnosis tool.”
Treatment

Treatment results

Home-based management of malaria is said to “encompasses components, such as establishment of a suitable platform that empowers caregivers to recognise malarial illness early and respond accordingly, community-based training programmes that equip caregivers with adequate knowledge and capacity to respond to malarial illness, and creation of an environment that facilitates the provision of antimalarial drugs as close as possible to the patients’ homes” according to Kua KP & al., The Impact of Home-Based Management of Malaria on Clinical Outcomes in Sub-Saharan African Populations: A Systematic Review and Meta-Analysis, Trop Med Health. 2024 Jan 8; 52(1):7, https://doi.org/10.1186/s41182-023-00572-2. The article reports on meta-analysis of 47 studies and concludes that “[h]ome management of malaria intervention was associated with significant reductions in malaria mortality and all-cause mortality.” Furthermore, “[h]ome malaria management combined with intermittent preventive treatment showed a significantly lower incidence risk of malaria than home management intervention that exclusively provided treatment to individuals with febrile illness suggestive of malaria.”
In Ghana, Mawuli MA & al. compared the effectiveness of unsupervised home treatment of malaria in a high-transmission district versus the same treatment in a low transmission district. Effectiveness of Artemether–Lumefantrine for Treating Uncomplicated Malaria in Low- and High-Transmission Areas of Ghana, Malaria J, 2024 Feb 6, 23:40, https://doi.org/10.1186/s12936-024-04850-0 reports that in the high-transmission district treatment was effective is slightly below the “WHO-defined threshold” of 90%, whereas it was effective in 100% of cases in the other area. The number of patients studied was small.

Adherence to guidelines

None this month

Side effects and complications

None this month
Drug resistance

In their article, Emergence of Plasmodium falciparum Strains with Artemisinin Partial Resistance in East Africa and the Horn of Africa: Is There a Need to Panic? Malaria J, 2024 Jan 25, 23:34, https://doi.org/10.1186/s12936-024-04848-8. Assefa A & al. argue that despite the emergence of partial artemisinin resistance in some P. falciparum strains in the area studied, standard artemisinin combination therapy (ACT) should continue to be efficacious in treating malaria.
The so-called Kelch13 mutations in P. falciparum are associated with artemisinin resistance. Jeang B & al. studied about 1000 dried blood spots from patients in a variety of locations in Kenya and Ethiopia and report in Molecular Surveillance of Kelch 13 Polymorphisms in Plasmodium falciparum Isolates from Kenya and Ethiopia, Malaria J, 2024 Jan 29, 23:36, https://doi.org/10.1186/s12936-023-04812-y that they found a variety of these mutations in more geographic locations than previously known, albeit the frequency of the mutations remains low. The authors discuss the implications of their findings in terms of the development of artemisinin resistance in the two countries.

Although the title of Fola AA & al., Genomics Reveals Heterogeneous Plasmodium falciparum Transmission and Population Differentiation in Zambia and Bordering Countries, medRxiv, 2024 Feb 11: 2024.02.09.24302570, https://doi.org/10.1101/2024.02.09.24302570 does not mention it, the genomic variations the authors found have striong correlation to resistance to artemisinin combination therapy. Similar to its sister publication, BioRxiv, MedRxiv publishes non-peer reviewed articles.
“Delaying and slowing antimalarial drug resistance evolution is a priority for malaria-endemic countries. Until novel therapies become available, the mainstay of antimalarial treatment will continue to be artemisinin-based combination therapy (ACT). Deployment of different ACTs can be optimized to minimize evolutionary pressure for drug resistance by deploying them as a set of co-equal multiple first-line therapies (MFT) rather than rotating therapies in and out of use.” Li EZ & al. “consider one potential detriment of MFT policies, namely, that the simultaneous deployment of multiple ACTs could drive the evolution of different resistance alleles concurrently and that these resistance alleles could then be brought together by recombination into double-resistant or triple-resistant parasites.” In Assessing Emergence Risk of Double-Resistant and Triple-Resistant Genotypes of Plasmodium falciparum, Nat Commun, 2024 Feb 15; 15(1):1390, https://doi.org/10.1038/s41467-024-45547-x the authors conclude that when prevalence of malaria is over one percent, multiple drug resistance risk “ranges from statistically similar to 80% lower under MFT policies than under cycling policies.”

Rosenthal PJ & al., Emergence, Transmission Dynamics and Mechanisms of Artemisinin Partial Resistance in Malaria Parasites in Africa, Nat Rev Microbiol. 2024 Feb 6, https://doi.org/10.1038/ s41579-024-01008-2 appears to be summary of other papers recently published in the subject.
Although it deals with a single case of malaria in a traveler to Mozambique, Casanova D & al.’s exceptionally well documented article, Artemisinin Resistance-Associated Gene Mutations in Plasmodium falciparum: A Case Study of Severe Malaria from Mozambique, Travel Med Infect Dis. 2024 Jan-Feb; 57:102684, https://doi.org/10.1016/j.tmaid.2023.102684 is important because in addition to reporting on artemisinin resistance, it also provides evidence to mutations associated with partial resistance to other drugs used in combination therapy, thereby documenting the presence of these mutations in the country.
New drug research
The antifolate drug pyrimethamine is used both in the treatment of malaria and chemoprophylaxis. Yet resistance to it is emerging among Plasmodium parasites. Verma K & al., Repurposing FDA-Approved Drugs to Target Malaria Through Inhibition of Dihydrofolate Reductase in the Folate Biosynthesis Pathway: A Prospective Approach, J Cell Biochem. 2024 Feb 12, https://doi.org/10.1002/jcb.30533 report on testing other antifolate drugs for structural and other similarities in order to identify which should be tested against wild and resistant P falciparum. The authors have identified two candidate drugs, duloxetine and guanethidine, both approved by the FDA for other indications.
Plant extracts and traditional treatments
Solanum incanum is a species of nightshade common in Africa and the Middle East. It is used in Kenyan folk medicine for a variety of ailments. Chiamah OC & al., Evaluation of the Antimalarial Properties of Solanum incanum L. Leaf Extract Fractions and Its Ability to Downregulate Delta Aminolevulinate Dehydratase to Prevent the Establishment of Malaria Infection, J Ethnopharmacol. 2024 Jan 5: 117613, https://doi.org/10.1016/j.jep.2023.117613 describes the effects of leaf extracts on experimentally infected mice. “The fractions extracted from S. incanum leaves … possess … antimalarial prophylactic properties, with the ethyl acetate extract fraction showing the most effective results.”
Annickia polycarpa, or African Yellow wood is a shrub found in West Africa, whose leaf decoctions are used in folk medicine against the symptoms of malaria. Kumatia EK & al., In vitro and in silico Anti-Malarial Activity and Cytotoxicity of N-Hexyl 1-O-Rutinoside (A Glycoside) Isolated from Annickia polycarpa (DC.) Setten and Maas Ex I.M. Turner (Annonaceae), J Ethnopharmacol. 2024 Jan 30; 319(Pt 2):117287, https://doi.org/10.1016/j.jep.2023.117287 describes the processes by which one particular extract of the leaf was shown to be efficacious against a laboratory strain of chloroquine resistant P. falciparum. The authors also conclude that this extract was not cytotoxic, which is somewhat confusing given an earlier statement in the abstract that n-hexyl 1-O-rutinoside was “weakly cytotoxic to human RBCs with high selectivity indices.”
Maafoh C & Onyedibe K, Alternative First-Line Malaria Treatment, Ann Afr Med, 2024 Jan-Mar; 23(1):5-12, https://doi.org/10.4103/aam.aam_35_23 advocates the use of Azadirachta indica (neem) in research of alternative drugs. The leaves of this plant, imported to West Africa from India have been used in folk medicine against malaria and the article cites several compounds derived from it that have been found to be antiplasmodial in the laboratory. The authors urge in vivo studies of these compounds.

Elmi A & al. studied over 40 different plants used by the population to treat malaria in the environs of Djibouti. While one of these, Balanites rotundofolia, made up 44% of usage by survey, the extracts of 3 others were found in the laboratory to be more efficacious. The paper, The Ethnopharmacological Study of Plant Drugs Used Traditionally in Djibouti for Malaria Treatment, J Ethnopharmacol. 2024 Feb 2: 117839, https://doi.org/10.1016/j.jep.2024.117839, concludes all the same that every plant being used showed some antiplasmodial activity in the laboratory.
Other

Rotimi K & al. surveyed the availability and affordability of treatment and chemoprevention drugs is various Nigerian states. They report in Private Sector Availability and Affordability of Under 5 Malaria Health Commodities in Selected States in Nigeria and the Federal Capital Territory, J Pharm Policy Pract. 2023 Dec 27;17(1):2294024, https://doi.org/10.1080/20523211.2023.2294024 that “[a]rtemisinin-based antimalarials for uncomplicated and severe malaria were the most available commodities. SPAQ1 and SPAQ2 used for seasonal malaria chemoprevention campaign were surprisingly also available in some outlets. However, only about half … of the surveyed outlets had stock of artemether/lumefantrine (AL1) and artesunate injection, respectively. The median price of surveyed products ranged from USD … 0.38 to USD 2.17 per treatment/test. Except for amodiaquine tablet and artemether injection, which cost less, all other originator brands cost the same or more than the lowest-priced generic. Antimalarial products were affordable as their median prices were not more than a day’s wage for the least-paid government worker. However, when the cost of testing and treatment with artemisinin-based combination therapies (ACTs) was assessed, testing and treatment with dihydroartemisinin/piperaquine were unaffordable as they cost more than 1.5 times the daily wage of the least-paid government worker.”
“An estimated 50% of suspected malaria cases in sub-Saharan Africa first seek care in the private sector, especially in private medicine retail outlets. Quality of care in these outlets is generally unknown but considered poor with many patients not receiving a confirmatory diagnosis or the recommended first-line artemisinin-based combination therapy (ACT). In 2010, a subsidy pilot scheme, the Affordable Medicines Facility malaria, was introduced to crowd out the use of monotherapies in favour of WHO-pre-qualified artemisinin-based combinations (WHO-PQ-ACTs) in the private health sector. The scheme improved the availability, market share, and cost of WHO-PQ-ACTs in countries like Nigeria and Uganda, but in 2018, the subsidies were halted in Nigeria and significantly reduced in Uganda.” Woldeghebriel M & al. studied the effects of this change in financial support and report in Assessing Availability, Prices, and Market Share of Quality-Assured Malaria ACT and RDT in the Private Retail Sector in Nigeria and Uganda, Malaria J. 2024 Feb 6; 23:41, https://doi.org/10.1186/s12936-024-04863-9 that with “the reduction or termination of subsidies for WHO-PQ-ACTs in Uganda and Nigeria, retail prices have increased, and retail prices of non-WHO-PQ-ACTs decreased, likely contributing to a shift of higher availability and increased use of non-WHO-PQ-ACTs… There was a 76% decrease in the market share of WHO-PQ-ACTs in Nigeria and a 17% decrease in Uganda. Malaria RDT availability remained low throughout.” The implications of the change are not covered in the abstract.
Campaigns and Policies

Based on extensive literature search, Oduoye MO & al., Unlocking the Potential of Novel RTS, S/AS01, and R21/Matrix-M™ Malaria Vaccines in African Nations, Health Sci Rep. 2024 Jan 4; 7(1):e1797, https://doi.org/10.1002/hsr2.1797 advocates vaccination policies in Africa that encompass the entire population, not just children in order to achieve herd immunity. While the paper (not the abstract) lists seven potential barriers to effective vaccination campaigns, the availability of the requisite doses of vaccines is not listed among them.
“Urban population growth in Nigeria may exceed the availability of affordable housing and basic services, resulting in living conditions conducive to vector breeding and heterogeneous malaria transmission.” This is of heightened importance now, given the appearance of An. stephensi in the country. Chiziba C & al., Socioeconomic, Demographic, and Environmental Factors May Inform Malaria Intervention Prioritization in Urban Nigeria, Int J Environ Res Public Health. 2024 Jan 10; 21(1):78, https://doi.org/10.3390/ijerph21010078 asserts that “[m]alaria transmission in urban areas will likely be reduced by addressing socioeconomic and environmental factors that promote exposure to disease vectors. Enhanced regional surveillance systems in Nigeria can provide detailed data to further refine our understanding of these factors in relation to malaria transmission.”
In addition to preventive measures, “malaria interventions include the availability of antimalarial medications, notably Artemisinin-based combination treatments (ACTs) and quick diagnostic test kits (RDTs)” As the title of Gakinahe GU & al., Availability of Antimalarial Medicines and Inventory Management at the Community Level: A Case Study of Bugesera District in Rwanda, BMC Health Serv Res. 2024 Jan 24; 24(1):136, https://doi.org/10.1186/s12913-024-10605-z indicates, the authors report on the outcome of interviews with community health workers (CHWs) in the district identified. “The CHWs reported to be actively involved in managing the antimalarial medicines inventory. Overall, 64.1% of CHWs indicated that the population could easily obtain antimalarial medicines from CHWs and 31.2% attested that people could also obtain antimalarial medicines from the health centers… 78% confirmed that the CHWs had the appropriate storage conditions for antimalarial medicines, while the overall stock out recorded was 3.20%.” CHWs also described “challenges, including but not limited to, lack of appropriate or dependable transportation and inappropriate medicines storage.”
“Quality improvement of malaria services aims to ensure that more patients receive accurate diagnosis, appropriate treatment, and referral. The Outreach Training and Supportive Supervision Plus (OTSS+) approach seeks to improve health facility readiness and provider competency through onsite supportive supervision, troubleshooting, and on-the-job training. As part of a multicomponent evaluation, qualitative research was conducted to understand the value of the OTSS+ approach for malaria quality improvement.” Altaras R & al.’s study was conducted by interviews and questionnaires. “Participants valued the relevance, adaptation, and digitization of supervision checklists; the quality and amount of contact with problem-solving supervisors; and the joint identification of problems and solutions, and development of action plans. Opportunities for improvement were digitized checklist refinement, assurance of a sufficient pool of supervisors, prioritization of health facilities, action plan dissemination and follow-up, and data review and use. The OTSS+ approach was perceived to be a useful quality improvement approach for malaria services.” The paper is Outreach Training and Supportive Supervision for Quality Malaria Service Delivery: A Qualitative Evaluation in 11 Sub-Saharan African Countries, Am J Trop Med Hyg. 2024 Feb 6: tpmd230316, https://doi.org/10.4269/ajtmh.23-0316.
OTSS is also the subject of Koko D & al.’s paper, How Outreach Training and Supportive Supervision (OTSS) Affect Health Facility Readiness and Health-Care Worker Competency to Prevent and Treat Malaria in Niger: A Secondary Analysis of OTSS Data, Am J Trop Med Hyg. 2024 Feb 6: tpmd230359, https://doi.org/10.4269/ajtmh.23-0359. At the conclusion of a four stage (“round”) program, the authors found “improved facility readiness, including an increased likelihood that HCWs had received classroom training, and facilities had increased availability of guidelines and algorithms by round 4 compared with round 1. Median HCW performance scores showed an improvement in the correct performance and interpretation of malaria rapid diagnostic tests, in classification of malaria as uncomplicated or severe, and in the management of uncomplicated malaria across the four rounds. For MiP {malaria in pregnancy} services, malaria prevention and the management of pregnant women with malaria also improved from round 1 to round 4.”
David A & al., Accessibility of Malaria Commodities in Geita District Council, Mainland Tanzania: The Experiences from Healthcare Providers and Clients, J Pharm Policy Pract. 2024 Feb 7; 17(1):2308611, https://doi.org/10.1080/20523211.2024.2308611 purports to report that Governmental facilities had 100% availability of “commodities,” by which the article apparently refers to testing materials and drugs. Yet the article also reports “stockouts” in these facilities without referring to the frequency of those occurrences. The authors refer to much lower availability of these commodities in private and faith-based facilities.
Awasthi KJ & al., Community Engagement Approaches for Malaria Prevention, Control and Elimination {ACE}: A Scoping Review, BMJ Open, 2024 Feb 15; 14(2):e081982, https://doi.org/10.1136/bmjopen-2023-081982 is a review of 75 relevant articles. “[F]ive levels … were used to categorise ACE – (1) Inform, (2) Consult, (3) involve, (4) Collaborate, and (5) Co-lead. Intervention activities were categorised as health education (HE), and/or health services (HS), and/or environmental management (EM) … Based on ACE levels, most studies were at the inform … and involve … level. HE … and HS … were the common intervention activities. HE informed communities about malaria, its prevention and vector control. EM activities were effective when complemented by HE. Community-based HS using locally recruited health workers was well-accepted by the community. Involvement of local leaders and collaboration with local stakeholders can be enablers for malaria intervention activities.
Epidemiology

Climate change, biodiversity and environment

“In Burkina Faso, the prevalence of malaria has decreased over the past two decades, following the scale-up of control interventions. The successful development of malaria parasites depends on several climatic factors. Intervention gains may be reversed by changes in climatic factors. [Traoré N & al.] investigated the role of malaria control interventions and climatic factors in influencing changes in the risk of malaria parasitaemia.” During the time period studied, the beneficial effect of proper use of ITN greatly outweighed the countervailing effect that was detected due to the increase in ambient temperature. The paper is Relative Effects of Climate Factors and Malaria Control Interventions on Changes of Parasitaemia Risk in Burkina Faso from 2014 To 2017/2018, BMC Infect Dis. 2024 Feb 7; 24(1):166, https://doi.org/10.1186/s12879-024-08981-2.
Adding to the already existing literature warning about the effects of climate change on malaria, Sadoine ML & al. modeled multiple factors, including potential further interventions in Uganda and published the results in Predicting Malaria Risk Considering Vector Control Interventions Under Climate Change Scenarios, Sci Rep. 2024 Jan 29; 14(1):2430, https://doi.org/10.1038/s41598-024-52724-x. The results showed upward trends in the annual malaria cases by 25% to 30% by 2050s in the absence of intervention but there was great variability in the predictions … The combination of IRS and LLIN, IRS alone, and LLIN alone would contribute to reducing the malaria burden by 76%, 63% and 35% respectively.
Risk factors

Xu E & al. “investigated the spatial risk of malaria infection at multiple timepoints after severe flooding in rural western Uganda employing longitudinal household surveys measuring parasite prevalence and leveraging remotely sensed information to inform spatial models of malaria risk in the 3 months after flooding.” The paper, Evolution of Spatial Risk of Malaria Infection After a Pragmatic Chemoprevention Program in Response to Severe Flooding in Rural Western Uganda, J Infect Dis. 2024 Jan 12;229(1):173-182, https://doi.org/10.1093/infdis/jiad348 reports that clusters of malaria risk emerge “in areas (1) that showed the greatest changes in Normalized Difference Vegetation Index from pre- to postflood and (2) where residents were displaced for longer periods of time and had lower access to” LLINs.

Abossie A & al. report that neighbors of patients with malaria are more likely also to become infected than the general population, if they live in low transmission areas. As reported in Higher Outdoor Mosquito Density and Plasmodium Infection Rates in and Around Malaria Index Case Households in Low Transmission Settings of Ethiopia: Implications for Vector Control, Parasit Vectors. 2024 Feb 6; 17(1):53, https://doi.org/10.1186/s13071-023-06088-2, there were also “higher outdoor mosquito densities and … a relatively higher outdoor mosquito density, which could increase the potential risk of outdoor malaria transmission and may play a role in residual malaria transmission.”
General epidemiology

During the survey Aninagyei E & al. conducted in their preparation for their paper, Molecular Speciation of Plasmodium and Multiplicity of P. falciparum Infection in the Central Region of Ghana, PLOS Glob Public Health. 2024 Jan 18; 4(1):e0002718, https://doi.org/10.1371/journal.pgph.0002718, they found P. vivax infections, which, according to the authors is the first reported instance in the country. Overall, P. falciparum monoinfections dominated (98+%), with P. ovale and P. vivax present as mixed in the rest.
“Malaria remains a significant public health concern in Niger, with the number of cases increasing from 592,334 in 2000 to 3,138,696 in 2010. In response, a concerted campaign against the disease has been initiated.” Tchole AIM & al., Epidemiological Behaviour and Interventions of Malaria in Niger, 2010-2019: A Time-Series Analysis of National Surveillance Data, Malaria J, 2024 Jan 19; 23:30, https://doi.org/10.1186/s12936-024-04835-z states that “[b]etween 2010 to 2019, the incidence rate of malaria decreased from 249.43 to 187.00 cases per 1,000 population in Niger. Niamey {the capital} had a high annual mean incidence rate and the lowest CFR {case fatality ratio} … [A]nalysis revealed a declining trend in malaria incidence for all age groups except the 10-24 years group, and the mortality rate and the CFR initially decreased followed by an increase in all age groups.” There is no explanation for the uptick and no information about subsequent years in the Abstract; the paper is not available for review.
Mandefro A & al. notes with concern the significant recurrence of malaria in Analysing the Six-Year Malaria Trends at Metehara Health Centre in Central Ethiopia: The Impact of Resurgence on the 2030 Elimination Goals, Malaria J, 2024 Jan 23, 23:32, https://doi.org/10.1186/s12936-024-04854-w. While malaria prevalence dropped to 9.8% in the area studied by 2021, it rose again to over 26% the following year. “Males accounted for a higher proportion (66%) of cases compared to females (34%). The age group 15–24 years experienced the highest malaria incidence at 42%. Notably, malaria cases peaked during autumn (September to November) at 43% and reached the lowest percentage during spring (March to May) at 13%.” The authors call for new efforts to reverse the unfavorable trend.
“Intervention against falciparum malaria in high transmission regions remains challenging, with relaxation of control efforts typically followed by rapid resurgence. Resilience to intervention co-occurs with incomplete immunity, whereby children eventually become protected from severe disease but not infection and a large transmission reservoir results from high asymptomatic prevalence across all ages.” Zhan Q & al. claim “that parasite population structure exhibited persistent features of high-transmission regions despite the considerable decrease in prevalence during transient intervention with indoor residual spraying (IRS).” How this relates to entigenic variation is not clear from the abstract of Hyper-Diverse Antigenic Variation and Resilience to Transmission-Reducing Intervention in Falciparum Malaria, medRxiv, 2024 Feb 5: 2024.02.01.24301818, https://doi.org/10.1101/2024.02.01.24301818. As already mentioned, MedRxiv publishes non-peer reviewed articles.
“Though Plasmodium vivax is the second most common malaria species to infect humans, it has not traditionally been considered a major human health concern in central Africa given the high prevalence of the human Duffy-negative phenotype that is believed to prevent infection. Increasing reports of asymptomatic and symptomatic infections in Duffy-negative individuals throughout Africa raise the possibility that P. vivax is evolving to evade host resistance, but there are few parasite samples with genomic data available from this part of the world.” Gartner V & al., Genomic Insights into Plasmodium vivax Population Structure and Diversity in Central Africa, Malaria J. 2024 Jan 18; 23:27, https://doi.org/10.1186/s12936-024-04852-y reports after full genomic analysis that “Plasmodium vivax from DRC is similar to other African populations” and suggests “that an endemic P. vivax population is present in central Africa. Intentional sampling of P. vivax across Africa would further contextualize this sample within African P. vivax diversity and shed light on the mechanisms of infection in Duffy negative individuals.”
Addressing the epidemiology of malaria is dependent on the ability to rely on data collection and storage. “Mozambique addressed critical malaria surveillance system challenges by rolling out an integrated malaria information storage system (iMISS) at the district level in February 2021, … eliminating the need for paper-based reporting to districts.” Stratil AS & al., Improving the Quality and Use of Malaria Surveillance Data: Results from Evaluating an Integrated Malaria Information Storage System at the Health Facility Level in Selected Districts in Mozambique, Am J Trop Med Hyg. 2024 Jan 23: tpmd230138, https://doi.org/10.4269/ajtmh.23-0138 is a report on how the system functions, using four evaluation areas: “data quality (reporting rate, timeliness, and fidelity) of monthly malaria reports electronically submitted to the iMISS, adoption of the iMISS for data-informed decision-making, system maintenance, and acceptability of the iMISS among target users.” Over the 6-month period of the study in seven districts, “86.1% of reported cases on the iMISS were consistent with cases recorded in paper-based reports, allowing for up to 10% discrepancy. In addition, 69.0% of expected monthly district meetings were held, and information from iMISS was discussed during 58.6% of these meetings.” However, “[m]aintenance issues, mostly related to tablet access and internet connectivity, were experienced by 74.5%” of health facilities.
Similarly in Madagascar, Yé M, & al., Identifying Strengths and Gaps in Data Management and Reporting through Malaria Routine Data Quality Assessment: Results from Two Health Regions in Madagascar, Am J Trop Med Hyg. 2024 Jan 23: tpmd230224, https://doi.org/10.4269/ajtmh.23-0224 reports that while data reporting was relatively timely (85% and 95%) in two districts studied, other measures of data quality, including completeness, support documentation, and use of the standard report forms were inadequate, between 44% and 68% during the period studied. “The findings suggest that regular data quality assessments should be implemented to guide decision making in Madagascar.”
In another paper on data collection and reporting, Evaluation of the Malaria Case Surveillance System in Kwazulu-Natal Province, South Africa, 2022: A Focus on DHIS2, Malaria J, 2024 Feb 14, 23:47, https://doi.org/10.1186/s12936-024-04873-7, Mabona M & al. focus on the province with the greatest chance of achieving South Africa’s goal of eliminating locally acquired malaria. In a study of the period 2016-20, “focusing on the District Health Information System 2 (DHIS2). The study assessed the data quality, timeliness, simplicity, and acceptability of the system. Key personnel from KZN’s Provincial malaria control programme were interviewed using self-administered questionnaires to evaluate their perception of the system’s simplicity and acceptability.” Utilizing data from 14 respondents, the authors found that while the reporting system was acceptable to the users, fewer than 2/3 of respondents submitted their reports on time. During the time reviewed, 81% of malaria cases were deemed to have been imported into the province.
“[M]alaria during pregnancy is a significant public health concern in malaria-endemic regions, which … increases maternal and neonatal mortality.” Kassie GA & al. focus on situations when malaria is asymptomatic and thereby escapes detection and treatment. In Asymptomatic Malaria Infection and Its Associated Factors Among Pregnant Women in Ethiopia; A Systematic Review and Meta-Analysis, Parasite Epidemiol Control. 2024 Jan 27; 24:e00339, https://doi.org/10.1016/j.parepi.2024.e00339 they report on ten articles with 3277 study participants. “The pooled prevalence of asymptomatic malaria infection among pregnant women in Ethiopia was 7.03%,” of which three quarters were P falciparum, the rest P vivax infections.” The authors conclude that “relying merely on reported symptoms may result in missed malaria cases. Therefore, regular screening and treatment protocols for malaria are recommended in antenatal care. It is also crucial to ensure that pregnant women have access to insecticide-treated bed nets and other effective malaria prevention measures.”
Spatiotemporal studies
Gaither C & al., Prevalence of Falciparum and Non-Falciparum Malaria in the 2014-15 Rwanda Demographic Health Survey, medRxiv. 2024 Jan 10: 2024.01.09.24301054, https://doi.org/10.1101/2024.01.09.24301054. MedRxiv publishes non-peer reviewed articles.

 

Always stay up to date - sign up for our newsletter here to get news and project updates.