Malaria Journal最新文献

Background: Amazonas is a region in northern Peru with the second-highest incidence of malaria. Approximately 95% of the cases are reported in the Condorcanqui province, where native communities living along the banks of Santiago River lack access to potable water, sewage, and electricity. This study aimed to analyse malaria's spatial, temporal, and climatic characteristics in Condorcanqui to guide future studies and prevention strategies.

Methods: A database provided by DIRESA-Amazonas was evaluated. Database included cases from 44 health facilities serving 112 native communities. According to the malaria control programs implemented in Peru, the study was divided into three periods: 2005-2010, 2011-2016, and 2017-2022. A Spearman correlation analysis was also conducted to assess the relationship between malaria incidence and climate variables.

Results: During the study periods, 10,632 cases were reported, including Plasmodium vivax (84.87%), Plasmodium falciparum (14.91%) and Plasmodium malariae (0.23%) infections. Annual incidence rates (AIRs) significantly varied across the study periods (p < 0.001). A significant reduction in malaria incidence occurred during the first period, largely attributed to PAMAFRO programme interventions. Subsequent periods, showed a gradual increase in cases, with a peak of P. vivax in 2019 and the reintroduction of P. falciparum. Males and individuals aged 0-11 years presented the greatest number of cases. Significant correlations were found between malaria incidence and the Oceanic Niño Index (ONI) at lag0 (ρ = 0.14, p = 0.037), corrected precipitation at lag1 (ρ = 0.16, p = 0.020), and minimum wind speed at lag1 (ρ = 0.15, p = 0.024).

Conclusions: Malaria incidence in Condorcanqui has increased over the last 5 years, driven by climatic influences such as the ONI, precipitation, and low wind speeds. Without immediate preventive efforts, cases are expected to continue rising. Effective control strategies must tackle the social, economic, and political issues that heighten vulnerability, such as poverty and limited healthcare access. Maintaining control initiatives and tailoring them to local needs will be essential for achieving long-term reductions of malaria in Peru.

Background: Senegal has made significant progress in reducing the burden of malaria, but transmission remains highly heterogeneous, with specific population subgroups likely at higher risk. Consultations with the National Malaria Control Programme (NMCP) and a review of available data identified nomadic pastoralists, gold miners, and Koranic school students as potential high-risk populations (HRPs). This study aimed to evaluate whether these populations are at higher risk of malaria and better characterize their exposure patterns to inform the design of targeted intervention strategies.

Methods: A mixed-methods study was conducted in the districts of Ranérou, Kaolack, and Saraya between November 2020 and December 2021. A formative assessment including key informant interviews (KII) and focus group discussions (FGD) was conducted with non-HRP and HRP members (nomadic pastoralists, gold miners, Koranic school students). A health facility-based case-control study was then conducted in nine health facilities across the three districts. 501 confirmed malaria cases and 1002 non-malaria controls were frequency matched by age and sex with a ratio of 1:2. A standardized questionnaire was administered to collect sociodemographic information, including occupation, use of malaria prevention measures, mosquito exposure, and travel history. Multivariable logistic regression was used to identify malaria risk factors.

Results: KIIs and FGDs indicated that nomadic pastoralists, gold miners and Koranic school students have high exposure to mosquito bites through outdoor sleeping, spending time outside at night and sleeping in informal structures, with important gaps in the coverage of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) and limited access to health services. Compared to controls, cases had higher odds of being a nomadic pastoralist (odds ratio (OR) 4.67 95% CI 1.96-11.11) or gold miner (OR 1.92 95% CI 1.20-3.07). No evidence was found of an association with being a Koranic school student (OR 1.39 95% CI 0.80-2.39).

Conclusions: Nomadic pastoralists and gold miners in the study areas are at higher risk of malaria. Targeted interventions are needed to cover gaps in malaria prevention coverage and access to health services.

Background: Cluster-randomized controlled trials (cluster-RCTs) have demonstrated variation in the epidemiological efficacy of different next-generation insecticide-treated net (ITN) types, with some providing shorter-lived impact than others. Further studies are needed to assess changes in the insecticidal durability of these ITNs over time to complement cluster-RCT results.

Methods: A series of experimental hut trials were performed to evaluate the bioefficacy of new and field-aged next-generation ITNs (PermaNet^® 3.0, Royal Guard^®, Interceptor^® G2) compared to a pyrethroid-only net (Interceptor^®) against pyrethroid-resistant malaria vectors in Covè, southern Benin. Field-aged nets were withdrawn from households at 12, 24 and 36 months. Net pieces cut from whole ITNs were analysed for chemical content, and susceptibility bioassays were performed during each trial to assess changes in insecticide resistance in the Covè vector population.

Results: Interceptor^® G2 induced superior mosquito mortality than the other ITNs across all time points. The improved mortality with Interceptor^® G2 compared to Interceptor^® was evident across all time points but was greater with new nets (odds ratio (OR) = 8.6, 95% CI [7.4, 10.1]) than field-aged nets (OR = 2.5, 95% CI [1.8, 3.5] at 12 months, OR = 2.4, 95% CI [1.6, 3.7] at 24 months and OR = 2.9, 95% CI [1.6, 5.1] at 36 months). New Royal Guard^® reduced mosquito fertility compared to the other ITNs, but this improvement fell after field-ageing, particularly at 24 months when it was similar to Interceptor^® (11% vs 3%, p = 0.08). When new, mortality was significantly higher with PermaNet^® 3.0 compared to Interceptor^® (OR = 3.6, 95% CI [3.0, 4.2]); however, this benefit was lost with field-aged nets at 12 months (OR = 1.1, 95% CI [0.8, 1.5]) and 24 months (OR = 0.6, 95% CI [0.4, 0.9]). Retention of the non-pyrethroid compound in next-generation nets was low after 36 months (27% for PermaNet^® 3.0, 26% for Royal Guard^® and 15% for Interceptor^® G2).

Conclusions: Interceptor^® G2 outperformed the other ITNs, confirming the superiority of pyrethroid-chlorfenapyr nets over other net types. When new, all next-generation ITNs showed superior bioefficacy compared to Interceptor^®; however, the size of this improvement fell after field-ageing due to poor durability of the non-pyrethroid compound. These findings emphasize the need to enhance the insecticidal durability of next-generation ITNs.

Background: Malaria prevention during pregnancy significantly minimizes maternal-fetal adverse events. However, optimal uptake of malaria preventive therapy in pregnancy (MPTp) remains a major challenge for both women living with HIV and those without. In Uganda, suboptimal uptake of MPTp is primarily due to inadequate knowledge among women. This study aimed to develop and assess the feasibility and acceptability of an educational video to improve knowledge of MPTp among pregnant women living with and without HIV.

Methods: This study describes the second phase of a mixed methods study conducted among pregnant women (living with and without HIV) and midwives from a public antenatal care clinic in Kampala, Uganda. The study was conducted from October 2022 to Jan 2024, and the first phase involved qualitative data collection from pregnant women, health workers, and Ministry of Health officials to develop a video-based intervention to enhance uptake of MPTp. The second phase involved administration of the developed intervention to a group of purposively selected pregnant women living with and without HIV. Questionnaires, focus group discussions, and interviews were used to collect data among women and midwives, and to assess feasibility and acceptability of the intervention. Quantitative data were summarized using descriptive statistics and analysed using different scales of measurement including the modified system usability scale and the Evidence-based Practice and Attitude Scale (EBPAS), which assessed acceptability among pregnant women and midwives, respectively. The qualitative data were coded and analysed using inductive and deductive thematic methods in Atlas ti.8.

Results: A total of 45 women and six midwives were enrolled in the current study phase. The mean age (± standard deviation, SD) of the women was 26 ± 6 years, and the median gestational age (interquartile range, IQR) was 24 (20-32) weeks, and less than half (42%, n = 19) were living with HIV. On the system usability scale, most women (91%, n = 41) rated the intervention as good or excellent, and most (93%, n = 42) were satisfied or very satisfied with the intervention. On the EBPAS, midwives perceived the intervention as reliable with Cronbach's alpha of 0.74, and all midwives found the intervention appropriate and feasible in their facility. All women comprehended and highly accepted the intervention.

Conclusion: The video-based intervention for uptake of MPTp was found acceptable among women and midwives and was feasible and appropriate to a public health facility. Future studies would test the effectiveness of the intervention in improving knowledge and uptake of MPTp.

Background: Children under five continue to bear a disproportionate burden of malaria morbidity and mortality in endemic countries. While the link between socioeconomic position (SEP) and malaria is well established, the causal pathways remain poorly understood, hindering the design and implementation of more targeted structural interventions. This study examines the association between SEP and malaria among children in Ghana and explores the potential mediating role of behavioural and socio-structural factors.

Methods: Data from the Ghana Demographic and Health Survey (DHS) 2022 were analysed. As part of the survey, children were tested for malaria using a rapid diagnostic test (RDT), and SEP was measured using a household asset-based wealth index. Mediation analysis (MA) using a regression-based approach was performed to assess mediated effects between SEP and malaria in children under five in Ghana through housing quality, educational attainment (EA), long-lasting insecticidal net (LLIN) use, indoor residual spraying (IRS), and healthcare-seeking behaviour (HSB). Reported are the total natural indirect effects (TNIEs) and the proportion mediated (PM).

Results: Of the 3,884 children included in the survey, 19.4% (757) had malaria. Belonging to a household with high SEP was associated with a 43% lower risk of malaria (Prevalence Ratio, PR = 0.57; 95% Confidence Interval, CI 0.46-0.71). Regarding indirect (mediated) effects, maternal EA of secondary school or higher (OR = 0.68; 95% CI 0.60-0.77; PM = 17.5%), improved housing (OR = 0.80; 95% CI 0.68-0.91, PM = 9.2%), LLIN use (OR = 0.95; 95% CI 0.90-0.99, PM = 2.1%) partially mediated the association between SEP and malaria. The combined effect of all three mediators was higher than those in a single mediator or two sequential mediators (with EA as the initial mediator) (OR = 0.58; 95% CI 0.51-0.68, PM = 25.7%). No evidence of mediation was observed for HSB and IRS.

Conclusion: We found evidence of mediation by EA, housing, LLIN use and IRS, suggesting that current biomedical and behavioural malaria control efforts could be complemented with structural interventions, such as improved housing and education. Future studies that test the effect of different or joint effects of multiple mediators based on prospective designs are recommended to strengthen the evidence.

Background: Post malaria neurologic syndrome (PMNS) is a rare complication of malaria, usually caused by Plasmodium falciparum. The clinical picture is highly variable and ranges from qualitative disturbances of consciousness and psychosis to damage to the peripheral nerves, usually occurring three to eight weeks after treated malaria.

Case presentation: We report the case of a 54-year-old male who presented with recurrent clinical symptoms three and a half weeks after severe falciparum malaria. After ruling out recurrent malaria, autoimmune encephalitis was suspected. Corticosteroid therapy led to a rapid improvement of the clinical symptoms. The extended examinations (including cranial MRI and FDG-PET/CT) revealed no pathological findings. Routine serologic autoimmune diagnostics remained negative. However, anti-septin complex antibodies were detected in the serum in a cell-based and a tissue-based immunofluorescence assay. Twelve months after discontinuation of corticosteroid therapy, the patient was free of immunosuppressants and completely asymptomatic.

Conclusion: To our knowledge, this is the first case of septin complex autoimmunity with encephalitis associated with PMNS. All physicians treating malaria patients should therefore be aware of this rare condition and consider extended autoimmune diagnostics if routine panels remain unremarkable.

Background: The eradication of Plasmodium vivax malaria is complicated due to the presence of hypnozoites, the hidden dormant form of the parasite that is present in the liver. Currently available drug regimens are effective at killing hypnozoites but cause side effects and are difficult to administer. Studies testing drugs for liver-stage malaria remain rare and mainly rely on the use of cancerous or immortalized hepatic cells and primary hepatocytes.

Methods: Organoids were used as platform to model liver-stage vivax malaria. Hepatic endoderm cells, endothelial progenitor cells and mesenchymal cells were generated from human induced pluripotent stem cells and self-assembled into liver organoids on top of Matrigel layer. Liver characteristic and maturity were examined through genes and proteins expression of liver markers, and liver functional tests before infected with Plasmodium vivax sporozoites. The infection was then verified by the detection of parasitophorous vacuole membrane proteins, Upregulated in Infectious Sporozoite 4 (UIS4), and blood-stage infection following co-culture with human reticulocytes.

Results: Generated liver organoids showed upregulation of liver specific transcripts including hepatic nuclear factor 4A (HNF4A), alpha-fetoprotein (AFP), and albumin (ALB) which also confirmed by the protein expression. Furthermore, those organoids resembled mature hepatocytes in terms of albumin secretion, fat and glycogen storage and cytochrome activity. Following invasion of P. vivax sporozoites, PvUIS4 was detected and the hepatic merozoites could develop into ring-stage and early trophozoites in human reticulocytes. Moreover, differential expression patterns of genes involved in lipid and cholesterol synthesis were also detected.

Conclusions: Stem cell-derived liver organoids resemble mature liver cells in terms of liver functions and are susceptible to infection with P. vivax sporozoites, paving the way for studies on the mechanism of hypnozoite formation and testing of possible hypnozoitocidal drugs.

Background: Few studies have described post-discharge morbidity of children with specific manifestations of severe malaria (SM) beyond severe malarial anaemia or cerebral malaria.

Methods: Children 6 months to 4 years of age admitted at Jinja and Mulago hospitals in Uganda, with one or more of the five most common forms of SM, cerebral malaria (n = 53), respiratory distress syndrome (n = 108), malaria with complicated seizures (n = 160), severe malarial anaemia (n = 155) or prostration (n = 75), were followed for 12 months after discharge, alongside asymptomatic community children (CC) (n = 120) of similar ages recruited from the households or neighbourhoods of the children with SM. Incidence and risk of hospitalizations, death or outpatient clinic visits were compared between children with SM and CC.

Results: 312/551 (56.6%) of children with SM had one or more post-discharge hospitalization over 12 months, compared to 37/120 (30.8%) of CC. Frequency of hospitalization was similar across all forms of SM. Compared to CC, children with SM had a significantly higher risk of all-cause hospitalization (adjusted hazard ratio (aHR) 1.91, 95% confidence interval (CI) 1.39-2.63, p < 0.001) and hospitalization for severe malaria (aHR 1.94, CI 1.36-2.78, p < 0.001), but a similar risk of outpatient clinic visits for malaria (aHR 1.24, 95% CI 0.89-1.73, p = 0.20). 82% of hospitalizations in children with SM (575/700) and CC (50/61) were due to malaria.

Conclusions: In this malaria endemic region, children with the five most common forms of SM had higher rates of post-discharge hospitalization than asymptomatic community children, and > 80% of hospitalizations were due to severe malaria. Studies of post-discharge malaria chemoprevention are urgently needed for children with SM, to determine if this treatment can reduce post-discharge morbidity.

Background: Ethiopia faces several severe challenges in terms of malaria elimination, including drug resistance and diagnostic evasion in the Plasmodium falciparum parasite, insecticide resistance in the primary Anopheles malaria vector, and, most recently, the invasion of the Asian malaria vector Anopheles stephensi. Novel malaria control methods are therefore needed, and in this paper, we describe the evaluation of a larval source management (LSM) strategy implemented in response to An. stephensi. The primary outcome was the malaria incidence rate compared between intervention and non-intervention sites in the presence of An. stephensi.

Methods: Intervention (Batu and Dire Dawa) and control (Metehara) towns were selected, and weekly malaria passive case detection data collected between 2014 and 2023 were obtained from the Oromia regional state and Dire Dawa City Administration Health Bureau. In addition, data regarding intervention were obtained from the President's Malaria Initiative (PMI) reports. Weekly malaria passive case data were used to evaluate the change in the estimated malaria incidence rate and trends of temporal patterns of the estimated malaria incidence rate before and after interventions. An interrupted time series model with a cyclic second-order random walk structure periodic seasonal term was used to assess the impact of LSM on malaria incidence rate in the intervention and control settings.

Results: An upsurge in malaria cases occurred after 2020 at both the intervention and control sites. The temporal patterns of malaria incidence rate showed an increasing trend after the intervention. The ITS model depicted that the LSM has no impact in reducing the malaria incidence rate at both intervention site Dire Dawa [immediate impact = 1.462 (0.891, 2.035)], [Lasting impact = 0.003 (- 0.012, 0.018)], and Batu [Immediate impact 0.007 (- 0.235, 0.249), [Lasting impact = 0.008 (- 0.003, 0.013)].

Conclusions: An overall increasing trend in the malaria incidence rate was observed irrespective of the implementation of LSM in the urban settings of Ethiopia, where An. stephensi has been found. Further investigations and validations of the incorporation of LSM into control activities are warranted.