Malaria Journal最新文献

This report outlines the process of malaria elimination in two municipalities, São Francisco do Sul and Araquari, located in Santa Catarina, Southern Brazil, from 1980 to 1985. Before 1948, Santa Catarina reported an annual average of nearly 60,000 malaria cases. The primary vector responsible for transmission was Anopheles (Kerteszia) cruzii, which exhibited high infestation levels in endemic areas. Malaria control measures in the state began in 1941 with the involvement of the National Malaria Service. The elimination process initially targeted Plasmodium falciparum and Plasmodium malariae infections, followed by a focus on Plasmodium vivax infections in 1962. Between 1980 and 1985, comprehensive efforts were undertaken in both municipalities to control and eliminate malaria. These efforts included bromeliad removal, DDT spraying, Malathion fogging, enhanced active and passive detection measures, and serological surveys to guide the radical cure of vivax malaria with chloroquine and primaquine. As a result of these interventions, both cities witnessed a significant decline in malaria incidence, going from 6.7 cases per 1000 residents to 0 cases in 1985. This report documents the first use of serology testing and treating in malaria elimination actions, demonstrating its potential to optimize resources by targeting treatment. The success of the combined interventions underscores the importance of significant resources, sustained effort, and political commitment to achieving elimination. The feasibility of serology-guided strategies in the 1980s highlights their continued relevance today as a model for achieving malaria elimination in endemic regions.

Background: The South African government is now implementing winter larviciding as a supplementary vector control tool. To achieve effective larviciding programme there is a need to understand the distribution of the breeding sites of vectors and their corresponding ecology. This study aimed to determine larval breeding sites of anophelines and characterize the physicochemical properties of water that promote the proliferation of Anopheles arabiensis immature stages.

Methods: A desktop survey of water bodies was carried out followed by a physical search of potential Anopheles breeding sites. Anopheline larvae were sampled from breeding sites in January and April 2021. At each breeding site, physicochemical characteristics of the water, including pH, electrical conductivity, total dissolved solids, salinity and turbidity, were measured. The collected Anopheles larvae were reared to adults and identified to genus and species level using morphological and molecular techniques. Factors associated with the presence of An. arabiensis larvae in the breeding sites were determined.

Results: Out of the 72 water bodies identified using desktop survey only 53% (n = 38/72) were identified through physical search. Of these 84% (n = 32/38) were positive for Anopheles larvae. A total of 598 Anopheles larvae were collected, of which 59.4% (n = 355/598) emerged into adults. Morphological identification of these adults, showed that the Anopheles gambiae complex accounted for 70% (n = 250/355) of the collections. From the 250 An. gambiae complex collected, 94% (235/250) were identified to species level by PCR and 6% (n = 15/250) failed to amplify. Of the 235 An. gambiae complex that were identified to species level, 62.5% (n = 147/235) were from January collections and 37.4% (n = 88/235) were from April collections. Molecular identification of the An. gambiae complex to species level showed predominance of An. arabiensis in April, 91% (n = 80/88). All physicochemical parameters differed significantly between the breeding site classes (p < 0.05 in all instances), except for electrical conductivity (p = 0.07). The aquatic habitats surveyed showed that the impermanency of the water bodies, neutral to alkaline pH, moderate salinity and low total dissolved solids were associated with the occurrence of An. arabiensis larvae.

Conclusion: This study showed that An. arabiensis primarily breed in small temporary water bodies characterized by neutral pH.

Background: Monitoring insecticide levels and physical integrity over time is essential for assessing the durability of insecticide-treated nets (ITNs), which largely depends on the net handling habits of users. This study determined the insecticide content and effectiveness of ITNs (Yorkool and PermaNet 2.0) at 6, 12, 24, and 36 months after a mass distribution campaign in Mali.

Methods: At 6 months (May, 2018), 12 months (December, 2018), 24 months (November-December, 2019), and 36 months (November-December, 2020), 30 nets were randomly collected from households in the districts of Kenieba and Kita in the southern part of Mali, together with information about ITN use and washing practices. The insecticidal effectiveness of the ITNs was assessed with the World Health Organization (WHO) cone test using a laboratory-reared, susceptible colony of Anopheles coluzzii. The residual insecticide content was measured by a nondestructive sampling technique with a portable field-adapted high-performance liquid chromatographic (HPLC) system (C-Vue®) validated by running samples in parallel with standardized WHO HPLC methods.

Results: At each survey time, nets were washed an average of three times over the previous 6 months, most commonly using Local soaps containing sodium hydroxide, detergent, or bleach. Using HPLC_CVue, the average deltamethrin concentration was 55 mg/m² at 6 months and gradually decreased to 14 mg/m² at 36 months for Yorkool nets. The values for the PermaNet 2.0 nets were 45 mg/m² at 6 months and 6 mg/m² at 36 months. Until the 24-month evaluation, the proportion of nets with minimal effectiveness was greater than 80% for both net types and sites. At 24 and 36 months, less than 80% of nets from both products and sites met the WHO optimal effectiveness criteria.

Conclusion: The WHO standardized cone test and C-Vue evaluation demonstrated that net type effectiveness and insecticide content were consistently lower than expected at 3 years, and users washed nets with local soaps containing sodium hydroxide, detergent or bleach. The C-Vue portable chromatographic device was used successfully for the first time in Mali to measure the insecticide concentration of ITNs.

Background: Severe malaria poses a significant challenge to under-five children in Malawi, leading to high rates of hospitalization and mortality. The World Health Organization has recently recommended post-discharge malaria chemoprevention (PDMC) as a preventive strategy for under-five children with severe anaemia in malaria-endemic regions. In response to this recommendation, Malawi's Ministry of Health (MoH) plans to implement PDMC nationwide. To facilitate effective implementation, the MoH has partnered with the Training and Research Unit of Excellence (TRUE) to conduct PDMC delivery trials to gather evidence for practical implementation in Malawi and similar settings. A key component of this initiative involved the MoH leading the co-design workshops with key stakeholders to foster collaboration, spur innovation, and develop user-centred strategies. This collaborative effort aimed to investigate optimal PDMC implementation strategies to guide the scale-up in Malawi and contribute to policy-making processes that enhance transparency, accountability, and ownership.

Methods: This participatory action research occurred in the Salima district, Malawi, from 11 to 12 May 2023. Two co-design workshops were utilized, involving policymakers (n = 15), healthcare providers (n = 8), and prospective users (n = 2). The approach consisted of two stages. First, separate information-gathering sessions were held with policymakers, healthcare providers, and prospective users. Second, a structured discussion was facilitated, allowing collaboration between policymakers, healthcare providers, and prospective users to develop strategies for delivering and integrating the intervention. Discussions were audio recorded, transcribed verbatim, and manually analyzed using a thematic approach.

Results: The inductive analysis yielded four overarching themes from the data. These key themes are PDMC adaptability, trialability, implementability, and sustainability. Stakeholders recommended adopting PDMC in Malawi, with health facilities as the optimal delivery option, ensuring that discharged children receive dihydroartemisinin-piperaquine doses for three months. PDMC aligns with existing systems, offering integration opportunities for managing childhood illnesses. However, gaps in policy development, approval, and health system strengthening-including supply chain, monitoring, evaluation, and follow-up-must be addressed to ensure PDMC's sustainability.

Conclusions: The co-design results indicate stakeholders' willingness to adopt and implement PDMC in Malawi. However, there is an awareness of the challenges that must be addressed to facilitate PDMC's successful implementation and sustainability.

Background: The problem of insecticide decay following their deployment in public health applications is frequently highlighted as an issue for sustained disease control. There are additional concerns that it also increases selection for insecticide resistance. Despite these concerns insecticide decay is largely absent from models evaluating insecticide resistance management strategies.

Methodology: The impact of insecticide decay is investigated using a model which assumes a polygenic basis of insecticide resistance. Single generation evaluations are conducted that cover the insecticide efficacy and insecticide resistance space for insecticides when deployed as monotherapies or mixtures to mechanistically investigate how insecticide decay impacts selection for resistance. The outcome is the between generation change in bioassay survival to the insecticides. The monotherapy sequence and mixture strategies were compared in multi-generation simulations incorporating insecticide decay, with the outcome being the difference in strategy lifespan.

Results: The results demonstrate that as insecticides decay, they can apply a much greater selection pressure than that imposed by newly deployed, non-decayed insecticides; this applies to both monotherapies and mixtures. For mixtures, selection for resistance is highest when both insecticides have reduced decayed efficacies; this also occurs if reduced dosages are deliberately used in mixtures. Insecticide decay was found to reduce the benefit of mixtures compared to sequential monotherapies, especially when reduced-dose mixtures are used.

Conclusions: Insecticide decay is often highlighted as an important consideration for mixtures and these results indicate its absence in previous modelling studies may be over-inflating the performance of full-dose mixtures.

In summary: as insecticides decay, they can impose increasing selection pressures for resistance with reduced ability to control the target insect populations. The optimal frequency with which decaying insecticides should be replenished is an important policy consideration.

Background: Malaria infection in pregnancy is a critical determinant of maternal and neonatal health outcomes in endemic regions. Intermittent preventive treatment of malaria in pregnancy (IPTp) using sulfadoxine-pyrimethamine has been recommended by the World Health Organization (WHO), but its uptake remains low because of factors such as gender norms and expectations. However, interventions to optimize IPTp uptake, especially in malaria-endemic regions, have resulted in a decline in malaria during pregnancy, maternal and neonatal mortality, low birth weight, and placental parasitaemia. This scoping review aimed to synthesize evidence on IPTp uptake, particularly emphasizing gender-related strategies.

Methods: The modified version of Arksey and O'Malley's framework and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) were adopted for this review. Documents were retrieved from the following electronic databases and search engines: scopus, Web of Science, CINAHL Complete (EBSCO), PubMed, WHO, Global Index Medicus, and Google Scholar. The titles and abstracts of the publications were independently screened via Rayyan review management software, and the data were organized using the reach, effectiveness, adoption, implementation, and maintenance (RE-AIM) framework and gender analysis matrix.

Results: A total of 32 studies met the inclusion criteria. The most reported criterion was the effectiveness of the interventions, which demonstrated an increase in IPTp uptake after the intervention. The gender analysis framework revealed that involving both men and women in decision-making processes, empowering women, and promoting shared roles could improve the success of IPTp interventions.

Conclusions: Interventions to increase IPTp uptake should be targeted at empowering women through education, increasing financial independence, and making decisions about their health.

Background: Seasonal migrant workers are at increased risk of malaria and can play a substantial role in transmitting the disease to receptive areas. Assessments conducted among these workers showed a high prevalence of malaria. This qualitative study aimed to explore the contributing factors and challenges to the high malaria prevalence among seasonal migrant workers in agricultural farm areas. The study also sought to identify potential solutions.

Methods: A descriptive phenomenological approach was employed to investigate the perceived causes, challenges, and solutions related to malaria prevalence among seasonal migrant workers in the development corridors of southwest Ethiopia. This approach emphasizes describing experiences as they are, without researcher interpretation. Data were gathered from 24 individuals purposefully selected for their close involvement with seasonal migrant workers and their experience with malaria issues in agricultural farm areas. Open-ended questions were used, and interviews were conducted in safe, quiet settings. Data management was performed using Open Code software version 4.03, and thematic analysis was applied to the contents.

Results: The study findings identified origin from highland areas, low health-seeking behaviour, working at night, and lack of use of long-lasting insecticidal nets (LLINs) as the perceived causes of high malaria prevalence among seasonal migrant workers by the study participants. Limited collaboration among stakeholders, a lack of migrant-friendly malaria prevention strategies, and inconsistent support for medical supplies were challenges highlighted by the key informants. Therefore, seasonal migrant workers were faced with high risk of malaria due to factors such as lack of immunity, delayed treatment, exposure to mosquitoes, and limited prevention efforts. Addressing these challenges is crucial for reducing malaria prevalence among this vulnerable population.

Conclusion: The study findings highlighted the need for targeted interventions to address the specific factors contributing to high malaria prevalence among seasonal migrant workers and to overcome the challenges in implementing effective malaria prevention strategies in this vulnerable population. Further study should be conducted to include the views and positions of seasonal migrant workers, owners of the farm areas, host communities, and political leaders.

Background: Virus co-infection or reactivation may modify the host response during cerebral malaria. Cytomegalovirus (CMV) DNAemia has been associated with increased morbidity and mortality in adults with sepsis; however, the impact of CMV DNAemia on adverse outcomes in children with cerebral malaria is unknown.

Methods: Clinical, physiological, and neurocognitive outcomes were compared in children aged 18 months to 12 years with cerebral malaria (N = 242) based on the presence or absence of CMV DNAemia 24 h after admission. The primary study outcome was subsequent in-hospital mortality. Secondary outcomes included the presence of acute kidney injury, neurocognitive impairment over a 2-year follow-up, and chronic kidney disease at the 1-year follow-up. Markers of platelet and endothelial cell activation and oxidative and nitrosative stress were measured to characterize the mechanisms by which CMV DNAemia might contribute to pathogenesis.

Results: CMV DNAemia was present in 33 children with cerebral malaria (13.6%) 24 h after admission. CMV DNAemia was not significantly associated with mortality in this study. Children with CMV-DNAemia had a higher prevalence of acute kidney injury than those without CMV-DNAemia (59.4% vs. 38.6%, p = 0.03). There was no difference in the prevalence of chronic kidney disease or long-term neurocognitive impairment based on the presence of DNAemia. CMV DNAemia was associated with elevated plasma levels of P-selectin, angiopoietin-1, asymmetric dimethylarginine, and platelet counts.

Conclusions: In children with cerebral malaria, CMV DNAemia is associated with acute kidney injury but not in-hospital mortality, chronic kidney disease, or long-term neurocognitive impairment.

Background: The state of Goa in western India is world-renowned for its coastline and attracts millions of tourists across the world. Historically, Goa was among the malaria-endemic states in India, with Plasmodium vivax contributing to the majority of the cases. Past malaria outbreaks in Goa have been linked to construction activities, and imported malaria cases threaten malaria elimination efforts in the state.

Methods: The malaria data from the National Centre for Vector Borne Disease Control (NCVBDC) and the Directorate of Health Services, Goa was used to study the spatiotemporal dynamics of Plasmodium falciparum, P. vivax, and mixed infection in Goa from 2000-2023. The spatiotemporal distribution of indigenous and imported malaria cases from 2014-2023 in the different primary/urban/community health centres (PHC/UHC/CHCs) of Goa was analysed using GIS. The spatiotemporal changes of the last three decades in Goa's land use/land cover (LU/LC) were assessed using Landsat satellite images, and its effect on malaria distribution was analysed.

Results: Over the study period (2000-2023), P. vivax contributed to 78.2% of the caseload. The malaria trend fluctuated from 2000 to 2008, with a steep decline observed from 2009 onwards, and in 2023, zero indigenous cases were reported. The six health centres of Candolim, Margao, Siolim, Vasco, Mapusa, and Panaji reported 57.8% of the total indigenous and imported malaria cases in Goa during 2014-2023. With 292 cases in 2023, the Porvorim UHC has emerged as a new hotspot of imported malaria cases. The LU/LC change analysis shows a four-fold increase of built-up area, from ~ 70 sq. km in 1991 to 260 sq. km in 2024, with strong spatial overlap between new built-up areas and malaria cases.

Conclusion: Due to the concerted parasite and vector control strategies of the state health department, Goa has achieved the target of zero indigenous malaria cases in 2023. Despite achieving this milestone, the threat of imported malaria cases leading to local outbreaks remains a serious concern.

Background: Despite the strides made in recent decades, the resistance observed in existing antimalarial drugs, and the intricate life cycle of the Plasmodium parasite underscore the pressing need to develop novel and effective therapeutic interventions. This article provides a comprehensive evaluation of the outcomes stemming from screening a library comprising 48 compounds (TCAMS) against Plasmodium falciparum.

Methods: This study focused on characterizing the IC₅₀ values of compounds from the Tres Cantos Antimalarial Set (TCAMS) library via a double-labelling method of P. falciparum parasites with SYBR Green-I and MitoTracker Deep Red, which were evaluated via flow cytometry. Evaluation of the cytotoxicity of the best candidates in human embryonic kidney (HEK293) cells, chemoinformatic analysis, and exploration of the effects of the compounds on the action of serotonin and melatonin in the erythrocytic life cycle of the parasite.

Results: IC₅₀ characterization confirmed that 93.75% of the compounds tested exhibited antimalarial activity at concentrations below 2 micromolar (µM), with 5 compounds showing IC₅₀ values below 50 nM (nM) (15.21 ± 5.97 nM to 45.82 ± 5.11 nM). Furthermore, 12 compounds presented IC₅₀ values between 50 and 100 nM (57.43 ± 12.25 nM to 100.6 ± 22.89 nM), highlighting their potent in vitro efficacy against P. falciparum. Cytotoxicity evaluation in HEK293 cells revealed that 12 from 17 compounds did not significantly reduce cell viability. Cheminformatics analysis clustered the compounds based on structural and physicochemical similarities, revealing distinct structural patterns. Exploration of hypothetical targets from the TCAMS library identified 27 compounds with potential targets, 15 specifically targeted serotonergic receptors. Subsequent serotonin and melatonin treatment experiments indicated that certain compounds could inhibit both effects on parasitaemia, suggesting a complex interaction with signaling in P. falciparum.

Conclusions: This study identifies promising antimalarial candidates with low IC₅₀ values and highlights the significance of targeting serotonin receptors in the development of potential antimalarial drugs.