Malaria Journal最新文献

Background: Indoor residual spraying (IRS) has been implemented in Rwanda in districts with high malaria transmission, including Ngoma District. The first IRS campaign (IRS-1) was conducted in March 2019, ahead of the peak malaria season, followed by a second campaign (IRS-2) in August 2020, targeting 89,331 structures. This study assessed factors influencing IRS uptake and evaluated the impact of IRS interventions on malaria morbidity in Ngoma District, Eastern Province, Rwanda.

Methods: A household survey employing multistage cluster sampling design was conducted in May 2021 to randomly select households. A structured questionnaire was administered to the head of household or a designated representative. Logistic regression, adjusted for the complex survey design and weighted for sampling, was used to identify factors associated with IRS uptake. Additionally, secondary data on malaria cases registered in the Rwanda Health Management Information System (RHMIS) from January 2015 to December 2022 were analyzed using interrupted time series analysis to evaluate the effect of IRS on malaria morbidity.

Results: A total of 636 households participated in the survey. Households headed by self-employed individuals (aOR = 0.07; 95% CI 0.01-0.55) and unemployed individuals (aOR = 0.18; 95% CI 0.03-0.99) were less likely to take up IRS compared to those headed by farmers. Households receiving IRS information through media channels (aOR = 0.01; 95% CI 0.00-0.17) were less likely to participate compared to those informed by community health workers. From the RHMIS data, 919,843 malaria cases were identified from January 2015 to December 2022. Interrupted time series analysis revealed that the baseline number of adjusted malaria cases was approximately 16,920. The first IRS intervention in March 2019 resulted in a significant reduction of 14,380 cases (p < 0.001), while the second intervention in August 2020 led to a reduction of 2495 cases, though this was not statistically significant (p = 0.098).

Conclusion: This study demonstrates the effectiveness of IRS in reducing malaria incidence in Ngoma District and highlights the role of socioeconomic factors and sources of information in influencing IRS uptake. To maximize the impact of IRS and ensure equitable benefits, targeted strategies, enhanced IRS education, and integrated malaria control approaches, including the use of bed nets, are crucial.

Background: Malaria poses a significant public health threat globally, particularly in African regions, where asymptomatic malaria is a considerable logistic problem. Individuals with asymptomatic malaria do not seek treatment, and thus they are invisible to health facilities and represent a substantial hidden reservoir of Plasmodium species. This study aimed to determine the prevalence of asymptomatic malaria and its associated factors in Gorgora, western Dembia district, Northwest Ethiopia.

Methods: A community-based cross-sectional study was conducted from May to June 2023 in the Gorgora area, Western Dembia district, Northwest Ethiopia. Data were collected using a semi-structured questionnaire. Giemsa-stained blood smear microscopy was employed for the diagnosis of Plasmodium species. The data were entered into Epi Data version 4.6 and exported to SPSS version 25 for analysis. Bivariate and multivariable binary logistic regression analyses were conducted to identify associated factors.

Results: Among the 357 individuals who participated in this study, 9.2% (33/357) [95% CI 6.40-12.70: p = 0.000] were confirmed to be infected with Plasmodium species. Plasmodium falciparum and Plasmodium vivax accounted for 66.7% and 33.3%, respectively. Not using bed nets [AOR = 7.3, 95% CI 2.08-23.46, p = 0.006)], previous malaria history [AOR = 2.6, 95% CI 1.01-6.45, p = 0.041], outdoor activities at night [AOR = 8.3, 95% CI 3.21-21.30, p = 0.000], and family size [AOR = 3.3, 95% CI 1.18-9.22, p = 0.023] were significantly associated with asymptomatic malaria (p < 0.05).

Conclusions: A considerable proportion of asymptomatic Plasmodium infections was found which likely act as a reservoir of transmission. This has implications for ongoing malaria control programmes that are based on the treatment of symptomatic patients and highlight the need for intervention strategies targeting asymptomatic carriers. Not using bed nets, engaging in outdoor activities at night, and having a family size of more than five increased the odds of developing asymptomatic malaria. The district health office and health extension workers should collaborate to promote the regular use of mosquito bed nets among community residents.

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: 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: 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: 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.