Malaria Journal最新文献

Background: Malaria remains a major global public health concern with the greatest burden in tropical and subtropical regions, particularly sub-Saharan Africa. Uganda ranks among the world's highest burden countries, with its warm temperatures, abundant rainfall and diverse mosquito breeding habitats sustaining year-round malaria transmission in malaria endemic areas. This study assessed malaria incidence trends and their association with climate variables in Yumbe district, Uganda.

Methods: A retrospective ecological time-series study analysed malaria incidence (2017-2021) in Yumbe district, Uganda, using District Health Information System reports and Uganda National Meteorological Authority climate data (daily temperature and rainfall). Data were cleaned in Excel and analysed in R software V4.5.1. Monthly/annual summaries, seasonal pattern graphs, Kendall's tau correlations for non-linear associations, and Multiple Linear and Poisson regressions with lag effects were done. Time series analysis involved seasonal decomposition, cross-correlation, and ARIMAX modelling. A multivariable OLS regression on log(1 + cases) with best-lagged rainfall and minimum temperature further assessed climate influence.

Results: Between 2017 and 2021, a total of 2,066,711 malaria cases were reported in Yumbe district. Malaria trends closely followed rainfall patterns, peaking during the period of high precipitation. Time-series analysis showed that rainfall was positively associated with malaria incidence at one-month lag (β = 0.38, p < 0.05), while minimum temperature was inversely associated (β = - 0.29, p < 0.05). Statistical analysis revealed rainfall (mm) strongly led malaria cases by 1 month (r = 0.759, p < 0.001). Maximum temperature showed no significant effect on malaria incidence.

Conclusion: Malaria incidence in Yumbe district is strongly influenced by rainfall and minimum temperature. This study highlights the role of climate variability in malaria transmission in malaria endemic areas. Integrating climate data into surveillance and early warning systems could enhance timely interventions in malaria endemic areas like Yumbe district.

Background: Compliance with evidence-based treatment guidelines, supported by quality-assured parasitological diagnosis, is the mainstay of malaria case-management in Nigeria. However, despite increased attention, the quality of inpatient paediatric and adult, test-and-treat malaria case-management, and routine accuracy of malaria microscopy, has rarely been examined in public and private hospitals.

Methods: A cross-sectional assessment was undertaken at 18 public and private hospitals in September 2024 in Kano State, Nigeria. Data collection included hospital assessments, interviews with inpatient health workers, review of all paediatric and medical ward admission files for August 2024, and re-checking of routine malaria slides archived during the 3-month post-assessment period. Descriptive analyses included 18 hospitals, 72 health workers, 2,814 suspected malaria admissions, and 211 malaria slides.

Results: Nearly all hospitals (94.4%) provided parasitological diagnostic services (microscopy or RDT) and stocked recommended antimalarials (injectable artesunate and ACT). Most health workers had received training on severe malaria (73.6%), but only 16.7% received supportive supervision. The composite test-and-treat performance was 39.3%, higher for children than adults (45.7% vs 26.5%) and in public compared to private hospitals (39.8% vs 30.8%). Among suspected malaria patients, 73.7% were tested on admissions and 90.2% of those with severe malaria were treated with artesunate. Children, compared to adults, were more commonly tested (79.8% vs 61.7%) and treated with artesunate (93.5% vs 80.1%). Patients in private hospitals, compared to public, were more often tested (84.3% vs 73.0%) but less frequently treated with artesunate (73.1% vs 91.2%). Only 30.0% of artesunate-treated patients were prescribed ACT-more commonly among adults than children (48.3% vs 23.0%) and in private than in public hospitals (89.2% vs 26.9%). ACT use for admitted non-severe cases was rare (2.4%), whereas non-compliance with test negative results was high (75.8%). The sensitivity, specificity, positive and negative predictive values of routine microscopy compared to expert readings were 93.2%, 42.5%, 29.9% and 95.9%, respectively.

Conclusions: Inpatient compliance with malaria test-and-treat guidelines varied between performance tasks, age groups, and hospital sectors. Clinicians can be confident in negative slides but should be cautious with positive results. Quality assurance of malaria diagnosis and continuous clinical and laboratory quality improvement interventions, with enhanced linkages, are needed.

Background: Malaria remains a leading cause of morbidity and mortality, particularly among children under five years of age in sub-Saharan Africa. Nigeria has the highest burden of malaria cases worldwide, accounting for 26% of all cases. The introduction of the R21/Matrix malaria vaccine is promising for reducing the malaria burden. However, vaccine awareness, perceptions, and willingness to pay among caregivers are key to ensuring successful rollout. This study assessed caregivers' awareness, perceptions, acceptability, and willingness to pay for the R21/MATRIX malaria vaccine in endemic communities in Lagos, Nigeria.

Methods: A community-based cross-sectional survey was conducted among 372 caregivers of children under five years of age. A multistage sampling technique was employed to select respondents from five malaria-endemic communities in Lagos. Data were collected via a semi-structured, interviewer-administered questionnaire. Descriptive statistics were computed, and binary logistic regression was used to identify predictors of vaccine awareness, perception, and willingness to pay.

Results: Awareness of the R21/MATRIX vaccine was low (9.7%), with the internet as the primary source of information. Positive perceptions of the vaccine were high, with 98.1% of caregivers believing it to be safe and effective. Acceptability was also high, as 76.6% of the caregivers indicated that they would "definitely" vaccinate their child. Willingness to pay was reported by 71.2% of the respondents, with 51.9% willing to pay between ₦1,001-₦5,000 per dose. The factors significantly associated with awareness included gender, marital status, and relationship with the child (p < 0.05). Higher household income and guardianship status increased the likelihood of willingness to pay (p < 0.05).

Conclusions: Despite the low awareness of the R21/MATRIX malaria vaccine, caregivers demonstrated a strong positive perception, high acceptability, and moderate willingness to pay. Targeted community awareness campaigns focused on the benefits and safety of the vaccine are essential to improve knowledge of the vaccine in endemic communities.

Background: New malaria control tools are urgently needed. Transmission-blocking vaccines (TBVs) target sexual parasite stages in mosquitoes to prevent disease spread. TBV testing requires specialised mosquito transmission assays, such as the Direct Skin Feeding (DSF) bioassay. DSF is a xenodiagnostic tool that mimics parasite transmission to mosquitoes as it naturally occurs but has not previously been scaled up nor standardised for use in clinical trials.

Methods: DSF bioassays were performed on large cohorts of participants, including children five years and older, during observational and interventional studies conducted over a 15-year period at sites around Bamako, Mali. Human, mosquito and parasite parameters were monitored to assess DSF safety and acceptability, vector performance, and individual- and population-level transmission dynamics. Standardised procedures developed for DSF included mosquito colony maintenance, mosquito preparation for DSF, feeding procedures, quality control metrics, ethical approaches and volunteer follow-up.

Results: From 2011 through 2025, 37,984 DSF bioassays were performed on 2,796 rural study participants aged 5 years and older, at two Mali study sites. DSFs were well-accepted and safe, with a low refusal rate (0.8% of subjects in vaccine studies) and rare adverse events (AE) that met grading criteria (11 subjects; 0.032%). The few immediate and short-term skin reactions that met AE grading criteria were mild or moderate in severity, all resolving within 48 h. DSF infrastructure was progressively scaled up to a capacity of 120 assays per day requiring 36,000 female mosquitoes per week. Rates of DSF positivity were highest in studies where feeds were conducted on individuals with known Plasmodium falciparum parasitaemia (average 18.4%) vs studies where feeds were conducted on all participants irrespective of blood smear status (average 1.6%).

Conclusions: The DSF bioassay is a xenodiagnostic tool to detect transmissible malaria parasites, and a scalable and safe method for evaluating TBV efficacy. DSF offers several advantages including close mimicry of naturally occurring transmission, simplicity of performance and standardisation, and scalable throughput to support late-stage vaccine trials. While parasite transmission rates measured by DSF were low overall at study sites in Mali, sufficient transmission endpoints are generated to assess efficacy of interventions that interrupt transmission, supporting the DSF bioassay as a surrogate efficacy endpoint for TBV studies.

Malaria remains a global health concern, with Africa bearing the highest global burden of malaria, as Plasmodium falciparum malaria remains the leading cause of malaria-related mortality on the continent. The transmission dynamics of malaria are shaped by a combination of factors, including climate conditions, economic constraints, geographic variability, human activities, and security instability. Owing to repeated infections and widespread implementation of early interventions, there has been a notable rise in cases of clinically atypical malaria and asymptomatic Plasmodium carriers, which increases the risk of misdiagnosis and underdiagnosis. Despite these challenges, African nations have made substantial progress in malaria control and elimination. Key advancements include, increased distribution of insecticide-treated nets use, increased indoor residual spraying, widespread rapid diagnostic tests, intermittent preventive treatment in vulnerable populations, deployment of artemisinin-based combination therapies (ACTs), and of late, the deployment of malaria vaccines to children under 5 years. Between 2000 and 2022, the WHO African Region reported a 40% reduction in malaria incidence and a 60% decline in mortality. Nonetheless, the continent faces emerging threats that could hinder further progress. These include persistent poverty, the effects of climate change, inadequate healthcare infrastructure and coverage, increased outdoor transmission linked to changing mosquito behavior, the appearance of new vector species, and rising resistance to both antimalarial drugs and insecticides. To address these challenges, a multi-faceted strategy is essential. This includes cross-border prevention and control efforts, expansion of seasonal malaria chemoprevention programmes, identification of molecular markers of resistance, development of novel antimalarial agents, and scaled-up implementation of vaccines such as RTS,S/AS01 and R21/Matrix-M. Implementation of approaches employed by countries such as China in malaria elimination and strengthening global-Africa cooperation in the fight against malaria could further accelerate progress. This review aims to provide a comprehensive overview of global malaria with a focus on Africa and global efforts toward the continent's malaria elimination goals.

Background: Serine/arginine-rich splicing factor 1 (SR1), an orthologue of hypothetical RNA-binding protein (HRB1) in yeast, is essential to the asexual development of Plasmodium falciparum and P. berghei. However, their interacting proteins in malaria parasites remain unclear.

Methods: To identify SR1-interacting proteins in malaria parasites, transgenic Pb ANKA expressing green fluorescent protein-fused PbSR1 (PBANKA_1232100) was generated and performed immunoprecipitation coupled to mass spectrometry (IP-MS) using the transgenic parasites. To investigate the developmental stage at which PbSR1 and RhopH2 are expressed, transgenic parasites co-expressing the fusion proteins PbSR1::GFP and RhopH2::mCherry were generated and western blot analysis and live-cell fluorescence imaging were performed.

Results: The fluorescence signal of PbSR1::GFP was stronger in nuclei than the cytoplasm of malaria parasites. IP-MS of the transgenic parasites indicated that PbSR1 interacts with nuclear proteins, including RNA-binding protein and small nuclear ribonucleoprotein, and cytoplasmic proteins, such as RhopH1 (or Clag3), RhopH2, and RhopH3. Live-cell fluorescence imaging showed that co-localization of PbSR1 and RhopH2 in the cytoplasm was observed in trophozoites and gametocytes but not mature schizonts and merozoites. From these results, trophozoites, immature schizonts and gametocytes are candidate stages at which cytoplasmic PbSR1 interacts with RhopH2.

Conclusions: PbSR1 interacts with nuclear proteins and rhoptry proteins.

Background: Pathogen genotyping via polymerase chain reaction (PCR) amplicon sequencing (AmpSeq) is an informative disease surveillance tool. Several large AmpSeq panels containing > 100 multiplexed PCR amplicons have been developed as alternatives to whole-genome sequencing (WGS) methods for the Plasmodium spp. parasites that cause malaria, especially for parasite drug resistance tracking and relatedness analysis. However, these large multiplexes typically yield sparse data for samples with parasitemia below 10 parasites/μl. Smaller multiplexes optimized for low-parasitemia genotyping have received insufficient methodological work but have the potential to serve multiple important use cases. Managing contamination risk during PCR steps represents another key methodological gap that requires attention in the AmpSeq field.

Methods: Here we describe a new 6-locus Plasmodium falciparum AmpSeq 'miniplex' (SIMPLseq) optimized for high-sensitivity analyses that also integrates a contamination detection system based on well-specific inline barcodes applied during first-round PCR (PCR1; in addition to conventional indexing steps during second-round PCR). We assess panel diversity using publicly available WGS and use mock samples to estimate sensitivity and precision relative to 4CAST, a previously described miniplex. We also create deliberate contamination events to assess contamination detection rigor and estimate unintentional contamination rates during assay application to malaria-infected dried blood spots collected in Mali.

Results: SIMPLseq shows high haplotypic diversity in silico, distinguishing 96.0% of sample pairs drawn randomly from 12 subnational sample sets. SIMPLseq outperforms 4CAST in sensitivity analyses, achieving 100% average locus detection at ≥ 0.5 parasites/μl and ≥ 50% average locus detection at 0.25 and 0.125 parasites/μl, with zero false-positive haplotypes at a 1% detection limit across 25 replicates. Inline barcoding does not significantly affect yield when using a 'sentinel' design, whereby one of the six multiplexed PCR1 primer pairs contains the well-specific sequence pair. Sentinel barcoding correctly identified all 24 contaminations introduced deliberately during PCR1 product handling and identified 39 unintentional contaminations in the 1420-sample Malian run.

Conclusions: SIMPLseq significantly extends the malaria genomic epidemiology toolkit, coupling high-sensitivity P. falciparum genotyping with PCR contamination detection in a simple laboratory protocol that uses only open-source reagents and does not require a costly pre-amplification step. Key prospective use cases for SIMPLseq include recurrent infection classification, polyclonality estimation, and genotypic infection endpoint application to intervention efficacy trials.

Background: Anopheles funestus group and Anopheles gambiae complexes are among the most efficient malaria vectors in Africa, thriving in a variety of environments and well adapted to develop in semi-permanent and permanent water bodies. This study investigated the spatial distribution of the An. funestus group and their contribution to malaria transmission in Burkina Faso.

Methods: An entomological survey was conducted from October to December 2022 across 67 sites within the ecological zones of Burkina Faso (once a month); An. funestus was detected in 22 of these sites. Mosquitoes were collected using pyrethrum spray catches (PSC) and identified at the species complex level using morphological keys. A polymerase chain reaction (PCR) was performed for species identification among An. funestus group, blood meal sources and Plasmodium falciparum infection.

Results: A total of 617 members of the An. funestus group (45 males and 572 females) were collected across eight regions of Burkina Faso. Anopheles funestus s.s. was the most prevalent specie identified with a frequency of up to 95% (589/617). Most An. funestus s.s. were found in the Hauts-Bassins and the Sud-Ouest regions with 30% (177/589) and 55% (329/589), respectively. Hybrids between An. rivulorum and An. rivulorum-like were identified at a frequency of 3.57% (22/617). Additionally, results showed a high prevalence of zoophilic behaviour (64.3% of the blood source) in An. funestus. Plasmodium falciparum infection was detected in 5.76% (33/572) of the An. funestus s.l. populations with a frequency of 5.6% (32/572) and 0.174% (1/572) in An. funestus s.s. and An. rivulorum-like, respectively.

Conclusions: This study updates the distribution of the An. funestus group and its potential role in malaria transmission in Burkina Faso. It emphasizes the need to strengthen malaria vector surveillance and highlights the importance of incorporating An. funestus in developing innovative vector control interventions.

Background: Mathematical modeling can be a useful approach to explore potential impact of malaria interventions and thereby inform resource prioritization decisions. However, expertise for applied modeling for public health decision-making is limited in malaria-endemic countries. A 4-month faculty enrichment program (FEP) in applied malaria modeling was implemented at Northwestern University, USA, in 2022 and 2023 with components including technical skills development, communication skills development, and domain knowledge on malaria epidemiology.

Methods: Two cohorts of FEP participants and instructors were interviewed at baseline, midline, and endline to understand their expectations, experiences, and challenges with the program.

Results: Participants valued their growth in technical expertise, research skills, and communication ability, as well as clear opportunities for knowledge transfer at their home institutions. Participants reported challenges with cross-disciplinary learning, balancing program components, and adapting to new teaching and learning styles. Instructors adapted program structures and teaching approaches to adjust to participant needs and reported strengthening of their own technical capacity.

Conclusion: Training programs for technical skill development must be informed by the needs and priorities of prospective participants and include continuous feedback mechanisms to respond to emerging needs. Multi-pronged approaches increase long-term program value to participants and help establish pathways for knowledge transfer.

Background: Malaria remains a leading cause of morbidity and mortality among children under five in Nigeria, with pronounced subnational disparities. This study analyzed the temporal and spatial inequalities in malaria incidence and mortality among children aged 0-4 years across Nigeria's 36 states and the Federal Capital Territory from 2010 to 2019.

Methods: Estimates from the Institute for Health Metrics and Evaluation (IHME) were analyzed using the WHO Health Equity Assessment Toolkit (HEAT). Subnational inequalities were quantified using five metrics: coefficient of variation (COV), difference (D), ratio (R), population-attributable risk (PAR), and population-attributable fraction (PAF).

Results: From 2010 to 2019, national malaria incidence declined from 103 to 74.5 cases (27.7% reduction), while mortality fell from 477.3 to 237.6 deaths per 100,000 (50.2% reduction). However, progress was uneven. Northern states such as Zamfara, Kano, and Katsina had the highest baseline burden in 2010 (incidence > 150 per 1000; mortality > 700 per 100,000) and, despite declines, remained among the most affected in 2019. Southern states including Lagos, Delta, and Anambra consistently recorded lower burdens (incidence < 60 per 1000; mortality < 300 per 100,000). Subnational inequality narrowed over time, with incidence COV peaking at 46.3% in 2013 before falling to 28.1% in 2019, and mortality COV declining from a 2013 peak of 42.9% to 22.3% in 2019.

Conclusion: Nigeria's malaria incidence and mortality among under-five children have decreased, but subnational disparities persist, particularly in northern states, although a reduction in D and R values indicates modest progress in equity, necessitating geographically targeted interventions.