Malaria Journal最新文献

Background: Asymptomatic malaria presents a significant barrier to malaria elimination efforts, particularly in endemic countries like Nigeria. Despite its public health relevance, no national-level pooled estimate of its prevalence and associated risk factors currently exists for Nigeria. This systematic review and meta-analysis aimed to synthesize existing data to estimate the prevalence of asymptomatic malaria and identify affected populations and risk factors across Nigeria.

Methods: A systematic search of PubMed, Google Scholar, and Scopus was conducted to identify observational studies reporting the prevalence of asymptomatic malaria in Nigeria. The review protocol was registered with PROSPERO (CRD42024591788). Eligible studies were screened using Rayyan software, and relevant data were extracted into Microsoft Excel. Meta-analysis was performed using Stata version 15.0. A random-effects model was applied to estimate the pooled prevalence. Heterogeneity was assessed using meta-regression and subgroup analyses, while publication bias was evaluated using funnel plot visualization.

Results: A total of 25 studies were included in the meta-analysis. The pooled prevalence of asymptomatic malaria in Nigeria was estimated at 33% (95% CI 26-41). Prevalence varied by population subgroup, ranging from 25% in the general population to 52% in children. Risk factor analysis revealed an overall prevalence of 19% related to education level, 36% based on sex, and 39% associated with insecticide-treated net (ITN) usage.

Conclusion: This review highlights a high prevalence of asymptomatic malaria in Nigeria, particularly among children. While asymptomatic infections sustain transmission, current evidence underscores the need to prioritize proven transmission-reduction tools. With reduced transmission, the asymptomatic reservoir can then be more effectively addressed through complementary strategies.

Background: Malaria is a leading cause of illness and death in pregnant women and newborns. In 2023, an estimated 12.4 million pregnant women were infected with malaria parasites, resulting in 351,000 low birth weight deliveries. Maternal and household factors associated with malaria in pregnancy and low birth weight were investigated in a high-transmission area of Uganda.

Methods: Data come from a randomized controlled trial of intermittent preventive treatment in pregnancy (IPTp) conducted from December 2020 to July 2024 in Busia District. Maternal and household data were collected using structured questionnaires. Women were followed through delivery including monthly assessment of microscopic parasitemia, assessment of placental malaria by histopathology, and birth weight. Associations between maternal and household factors were assessed: (1) parasitaemia at enrolment, (2) parasitaemia during pregnancy after starting IPTp, (3) high-grade placental malaria, and (4) low birth weight (< 2500 gm).

Results: Of 2,757 women enrolled, 2,728 (98.9%) had a household survey completed and were included in study. Overall, 38.1% had parasitemia at enrolment, 6.5% had parasitemia following initiation of IPTp, 6.4% had high-grade placental malaria, and 6.8% of live births had low birth weight. Parasitemia at enrolment was more common in those 16-21 years of age (RR = 1.62, 95% CI 1.31-1.99 p < 0.001), primigravida (RR = 1.86, 95% CI 1.57-2.21, p < 0.001)), and living in traditional houses (RR-1.17 95% CI 1.06-1.30, p = 0.002). These associations persisted after IPTp initiation: younger age (RR = 1.72, 95% CI 1.22-2.43, p < 0.002), primigravida (RR = 2.40, 95% CI 1.81-3.20, p < 0.001), and traditional housing (RR = 1.30 95% CI 1.01-1.60, p = 0.02). Maternal level of education was not associated with malaria parasitaemia both at enrollment and after initiation of IPTp. Primigravida was strongly associated with high-grade placental malaria (RR = 4.20, 95% CI 2.33-7.59, p < 0.001)) and low birth weight (RR = 2.14, 95% CI 1.18-3.89, p = 0.01). However, there were no significant associations between maternal age, level of education, household wealth, and household construction with high-grade placental malaria or low birthweight.

Conclusions: In an area of high malaria transmission, young primigravida women and those living in traditionally constructed houses had the greatest risk of malaria parasitemia during pregnancy. Primigravida women also had higher risks of low birth weight and high grade placental malaria.

Background: Malaria remains a major public health challenge in Ghana. However, heterogeneous transmission necessitates localized data for effective subnational targeting of control measures. The Ho Municipality, characterized by high rainfall and humidity ideal for year-round mosquito breeding, exemplifies a setting where such detailed epidemiological intelligence is needed but currently scarce. This study aimed to bridge this gap by analysing facility-based trends to inform precision public health interventions in this vulnerable region.

Methods: A retrospective cross-sectional study, performing a census of all available malaria microscopy records from three major healthcare facilities in Ho Municipality over 36 months (January 2020-December 2022) was conducted. Data were extracted from both paper-based logbooks and electronic health records. Descriptive statistics and multivariable regression analyses-specifically, a log-linear model was employed to identify factors associated with parasite density (presented as Geometric Mean Ratios, GMR) and a Poisson regression model to identify factors associated with test positivity (presented as Adjusted Prevalence Ratios, APR). All models were adjusted for age, sex, facility, and year.

Results: Among 27,171 tests, the overall test positivity rate (TPR) was 8.8%, showing a decline from 9.9% in 2020 to 7.2% in 2022. Significant disparities were observed: school-age children (5-12 years) had the highest TPR (18.0%), and a fourfold disparity existed between Ho Municipal Hospital (21.0% TPR) and Ho Teaching Hospital (5.2% TPR). Transmission peaked seasonally in August (13.9% TPR). Plasmodium falciparum was dominant (79.9% of confirmed cases). School-age children and adolescents demonstrated significantly higher parasite densities than adults (aGMR = 3.69 and aGMR = 3.57, respectively). Regression confirmed school-age children (aPR = 3.26) and adolescents (aPR = 3.49) as the highest-risk groups, with a significant age-sex interaction revealing elderly females were also at markedly increased risk (aPR = 2.15).

Conclusion: This study identifies persistent, significant disparities in malaria burden linked to specific age groups, sex, and health facilities in Ho Municipality. These findings underline the urgent need for a targeted intervention strategy, including school-based chemoprevention programs, enhanced diagnostic support and staffing for high-burden facilities, and pre-emptive vector control ahead of peak rainfall seasons to accelerate progress towards malaria elimination.

Background: Community engagement (CE) is essential for public health interventions. This is particularly important when introducing novel technologies, such as the Sterile Insect Technique (SIT), that require strong community understanding and acceptance. Against this background, arts-based CE strategies, including music, drama, and radio short stories, were developed and piloted, but their effectiveness remained unevaluated. This study assessed whether exposure to arts-based CE approaches influenced community knowledge, attitudes, and acceptance of the SIT in uMkhanyakude District, KwaZulu-Natal, South Africa.

Methods: A cross-sectional survey to understand the influence of arts-based CE approaches was conducted in the Jozini municipality, uMkhanyakude District, after community exposure to these CE productions. Structured interviews were conducted with randomly sampled community members. Data were collected on CE exposure and SIT-related knowledge, attitudes, and acceptance. A chi-square test and a stepwise ordinal logistic regression were used to analyse the data after adjusting for sociodemographic factors.

Results: Among 614 participants, only 26.2% (n = 161) were exposed to arts-based CE approaches. Those exposed were more likely to correctly identify that female mosquitoes feed on blood as compared to the unexposed (95.0% vs. 85.8%, p = 0.008), and to express support for SIT (e.g., 98.1% vs. 89.4% agreed with upcoming releases, p = 0.003). Exposure remained a significant predictor of SIT acceptance in multivariate models (OR 0.65, 95% CI 0.45-0.94). Positive attitudes and accurate knowledge also independently predicted greater acceptance.

Conclusion: Arts-based CE tools were effective in supporting the introduction of SIT by improving knowledge and acceptance. However, limited exposure suggests the need for more sustained and widely accessible engagement strategies to maximize reach and long-term impact. These findings suggest that artistic productions, especially when delivered through culturally relevant, multimodal formats, play a meaningful role in shaping community receptiveness to novel vector control methods like the SIT.

Background: From August to October 2022, a therapeutic efficacy study of Niger's first-line antimalarial, artemether-lumefantrine (AL), was conducted in four sites (Aderbissinat, Boboye, Aguié, and Baban Tabki) to evaluate its therapeutic efficacy and investigate for molecular markers of antimalarial drug resistance.

Methods: Children aged 5 to 15 years old with uncomplicated malaria were assessed in a 28 day in vivo efficacy study. Genotyping using three markers (msp1, msp2 and the PolyA microsatellite) and match counting using the WHO three-out-of-three algorithm, were used to distinguish recrudescences from new infections. A two-out-of-three algorithm was also utilized as a sensitivity analysis.

Results: PCR uncorrected and corrected efficacy results at day 28 were calculated. Resistance markers were analysed by next-generation sequencing. Uncorrected treatment efficacies were 62.0% (95% CI 54-74) in Aderbissinat, 95.4% (95% CI 91-100) in Aguié, 98.7% (95% CI 96-100) in Boboye, and 50.6% (95% CI 42-62) in Baban Tabki. After PCR correction, AL efficacy was 100%, 97.5%, 100%, and 93.5%, respectively. Marker analysis revealed a high prevalence of S108N, C59R, and N51I mutations in the pfdhfr gene, and S436A and A437G mutations in the pfdhps gene. No validated or candidate pfkelch13 mutations were observed.

Conclusion: In all four sites evaluated, AL retains therapeutic efficacies above the 90% WHO-recommended threshold using the primary three-out-of-three match criteria. In Aguié and Baban Tabki, efficacy remained above the threshold with certain match criteria and statistical approaches but fell below the cutoff using two-out-of-three matching and per-protocol methods, suggesting emerging efficacy concerns in southern parts of the country.

Background: The innovative automated haematology analyzer XN-31 has demonstrated comparable or, in some settings, superior performance to microscopy and rapid diagnostic tests (RDTs), and good concordance with polymerase chain reaction (PCR) in various endemic areas, particularly where Plasmodium falciparum is prevalent. The XN-31 applies the principle of flow cytometry to measure cell size and nucleic acid content to generate a two-dimensional cytogram in approximately one minute. This technique identifies P. falciparum and other species and provides % parasitaemia (MI-RBC%). This study evaluated the diagnostic performance of the XN-31 in Thailand, where Plasmodium vivax is predominant.

Methods: From November 2019 to June 2022, 349 patients suspected of having malaria were enrolled at the Hospital for Tropical Medicine, Mahidol University, Bangkok. Blood samples were collected via venipuncture and analysed using the XN-31, thick and thin film microscopy, RDTs, and PCR. The qualitative diagnostic accuracy of the XN-31 for detecting malaria parasites and identifying their species was compared with other methods. The quantitative diagnostic ability of the XN-31 was assessed by correlating the MI-RBC% values with % parasitaemia from thin film microscopy.

Results: Among the 349 samples, 125 were positive according to thick film microscopy (103 P. vivax, 17 P. falciparum, 3 Plasmodium knowlesi, 1 Plasmodium ovale, and 1 Plasmodium malariae). The XN-31 demonstrated 98.4% sensitivity relative to thick film microscopy as the reference method, outperforming the RDT (88.0%). All XN-31-positive samples were confirmed via PCR. The information on the parasite species, flagged as 'Malaria? (P.f)' or 'Malaria? (others)' by the XN-31, which depicts P. falciparum or other Plasmodium species, respectively, matched 100% with microscopic determination. The quantitative performance of the XN-31 was strongly correlated with that of thin film microscopy (correlation coefficient [r] = 0.903).

Conclusions: This is the first study to confirm the accuracy of the XN-31 for both qualitative and quantitative diagnoses in a malaria-endemic region dominated by P. vivax. The XN-31 is expected to be a useful diagnostic tool in similar endemic regions.

Background: Insecticide-treated nets (ITNs) remain a key intervention in malaria prevention. However, their protective effectiveness may decline with physical deterioration, even when usage remains high. This study assessed the impact of ITN physical integrity on children's exposure to Anopheles mosquito bites over a three-year period in Mali, using gSG6-P1 biomarker as an innovative immuno-epidemiological indicator of human exposure.

Methods: A three-year prospective cohort study was conducted from 2018, 2019, and 2020 in two rural health districts of Mali: Kéniéba using Yorkool^® ITNs and Kita using PermaNet^® 2.0 ITNs. A total of 586 children under five years old were enrolled and followed annually across 30 villages randomly selected into the two districts. Household surveys captured ITN ownership, usage patterns, and net condition. Net physical integrity was evaluated using proportional hole index (pHI). Blood samples were collected each year and analysed for anti-gSG6-P1 IgG levels, expressed as ΔOD. Net condition and specific IgG levels were analysed across time points and stratified by site and ITNs type.

Results: ITN usage remained high (> 75%) across all survey years, but the proportion of serviceable nets declined significantly, particularly for Yorkool^® (49% at 36 months versus 78% for PermaNet^® 2.0). Median anti-gSG6-P1 IgG levels increased concurrently, indicating rising exposure to Anopheles bites as net integrity deteriorated. Children sleeping under Yorkool^® nets showed higher specific IgG levels than those using PermaNet^® 2.0, suggesting reduced protective performance of Yorkool^® over time.

Conclusion: This study demonstrates that ITN effectiveness decreases as physical deterioration advances, even when usage is maintained. Monitoring net integrity through the gSG6-P1 biomarker provides an innovative, field-adapted approach to anticipate ITN protection failures and to support evidence-based decision-making in malaria control programmes.

Introduction: Accurate diagnosis of malaria, caused by Plasmodium falciparum, remains challenging in endemic resource-limited settings. Molecular diagnostics, like PCR, offer a higher sensitivity, but are often impractical at the point-of-care. A relatively simple molecular diagnostic test has been developed to overcome the technological challenges frequently encountered during the implementation of molecular tools. We present here the results of the field evaluation of this novel mini direct-on-blood PCR platform with lateral flow readout (dbPCR-NALFIA), in a rural setting of Burkina Faso.

Methods: A phase 3 diagnostic accuracy study was conducted over one year in a high P. falciparum transmission setting in Burkina Faso. Febrile patients of all ages (n = 438) were screened using PfHRP2-based RDT, microscopy, and the investigational dbPCR-NALFIA test. Reference diagnostic test was qPCR targeting the P. falciparum varATS gene. Diagnostic accuracy metrics (sensitivity, specificity, predictive values) and agreement (Cohen's kappa) were calculated for each method.

Results: Malaria prevalence by qPCR was 65.5% (287/438). A total of 99.2% (259/261) of P. falciparum microscopy-positive samples were detected by qPCR, 97.7% (253/259) detected with RDT and 99.6% (258/259) with the investigational dbPCR-NALFIA. Overall, 85.2% (149/177) of microscopy negative samples were also confirmed negative with qPCR. Among these qPCR negative samples, 80.5% (120/149) were concordantly negative by RDT, while 98.0% (146/149) were confirmed negative by dbPCR-NALFIA. Using qPCR as reference, the dbPCR-NALFIA demonstrated a sensitivity of 96.5% and specificity of 98.0%, comparable to RDT sensitivity (95.1%) and microscopy specificity (98.7%), but out-performed RDT specificity (80.8%) and microscopy sensitivity (90.2%). dbPCR-NALFIA detected 67.9% of sub microscopic qPCR-positive samples missed by the microscopy. Agreement with qPCR was the highest for dbPCR-NALFIA (kappa value = 0.90), compared to microscopy (kappa value = 0.80) and RDT (kappa value = 0.71).

Conclusion: The dbPCR-NALFIA shows excellent diagnostic performance to detect P. falciparum under field conditions. It addresses key limitations of other diagnostics and could play a vital role in case detection.

Background: Despite a significant reduction in the burden of malaria in the last decades, the disease remains a significant global public health threat. Community perception, knowledge, and practices are key determinants in malaria transmission. Mudzi is a border district in Zimbabwe, characterized by persistent malaria transmission despite having high indoor residual spraying coverages that meet the World Health Organization (WHO) indoor residual spraying (IRS) coverage thresholds. Human socio-economic behavioural factors driving persistent transmission have not been documented.

Methods: A mixed-methods cross-sectional study was conducted to establish knowledge, practices, and perceptions among Artisanal Gold Miners (AGMs) and Community members (CMs). Two active artisanal mining sites and catchment villages were purposively selected for this study. Malaria RDT test kits and blood slide examinations by microscopy were used to establish malaria parasitaemia prevalence. Data were collected via Kobo Collect and analysed using Microsoft Excel to generate frequencies and analyse for statistical differences.

Results: A total of 128 AGMs and 113 CMs were recruited. 277 individuals were tested for malaria using RDT and blood smear microscopy. Responses showed good knowledge of the cause and transmission of malaria. However, low risk perception and misconception among AGMs and CMs were observed. There was no significant difference concerning education, knowledge, and perceptions between AGMs and CMs. AGM predominantly lived in the open without protective measures for long periods. Community members and artisanal miners (AGMS) showed high preferences and utilisation of standard care offered through health facilities and community health workers (CHW). The majority of AGMs and CMs received health education from HCWs. Malaria prevalence across the groups was less than 1%.

Conclusion: High knowledge of malaria is not translating into preventative behaviour and high-risk perception among AGMs and CMs. There is a need to create innovative health education interventions that motivate individuals to increase risk perception and behaviour modification. Communities are likely to prioritize survival over malaria avoidance practices, therefore, an integrated intervention that addresses livelihoods and malaria prevention needs to be developed.

Consistent use of insecticide-treated nets (ITNs) for malaria prevention has been a challenge undermining the intervention's effectiveness. Perceptions of heat and absence of mosquitoes are among the reasons cited for non-use of ITN in populations with access. We conducted repeated household surveys across seasons in Ondo State of Nigeria to investigate seasonal changes in ITN use rates and potential determinant factors. Five household surveys were conducted in different months before an ITN distribution campaign in December 2021 followed by post-campaign surveys in April 2022, and in June, August and October 2023. Temperature and precipitation estimates up to 60 days before each of the surveys were used to investigate the potential effects of seasonal factors on proportions of people using ITNs among those with access (use behaviour). The study found significant associations between climatic factors and ITN use, with increases in the rainy season and reductions in the hot, dry season. Temperature and precipitation were negatively and positively associated with ITN use among populations with access respectively, suggesting the effects of heat and potentially mosquito abundance and perceived risk of malaria. A mixed-effects regression showed that each 1 °C increase in mean temperature during the 30 days preceding surveys was associated with a 9 percentage point decrease in ITN use rate (p = 0.006). Rainfall showed a smaller but significant positive association with ITN use. Each additional 10 mm of rainfall 31-60 days before surveys increased use rate by 0.7 percentage points (p = 0.013). Higher proportions of low-SES households within study clusters and a greater number of nets per person were significantly associated with increased ITN use, independent of climatic influences. Although overall ITN use is largely determined by access, this study provides evidence that, among populations with access, usage is further influenced by a complex interplay of multiple factors and climatic fluctuations. While previous research has explored associations between climate and ITN use, this study strengthens the evidence through state-level, repeated, within-population serial cross-sectional observations. The findings indicate that seasonal variations in rainfall and temperature are key determinants of ITN use behaviour. These patterns should inform the design of behaviour change communication strategies, as well as the timing of distribution campaigns and evaluation surveys. Interpretations of ITN use survey data should account for seasonal effects.