Prevention Efforts for Malaria

Towards promoting timely treatment: Uncovering the determinants of prompt malaria care seeking behavior among febrile children under-five years in Tanzania

BACKGROUND

Prompt diagnosis and effective treatment within 24 hours of fever onset is crucial for reducing malaria-related morbidity and mortality in under five children. However, research on the prompt care-seeking behaviors and their determinants in this demographic is limited. This study examined the prevalence of prompt care-seeking behaviors among under five febrile children in Tanzania and the associated determinants.

METHODS

This cross-sectional study analyzed data from the 2022 Tanzania Demographic and Health Survey (TDHS), including a nationally representative and weighted sample of 1,050 under-five children who experienced fever within two weeks prior to the survey. A weighted univariable and multivariable modified Poisson regression model with robust estimator was used to examine the association between prompt care seeking behaviors and explanatory variables, including child and caregivers' factors.

RESULTS

The prevalence of prompt care seeking for febrile children was 43.2%. Caregivers of female children had 18% less prevalences of seeking prompt care (95% CI 0.68-0.98) compared to caregivers with their male children. Caregivers aged 25-34 and 35-49 years had 36% (95% CI 1.05-1.78) and 61% (95% CI 1.16-2.23) higher prevalences of seeking prompt care for their children respectively, compared to younger caregivers aged 15-24 years. Caregivers with at least primary education had 50% (95% CI 1.12-2.02) higher prevalences of seeking prompt care compared to those with no formal education. Additionally, an increase in one household member was associated with a 3% increase in the prevalence of seeking prompt malaria care (95% CI 1.01-1.05).

CONCLUSION

In Tanzania, female children under five experience delays in care-seeking for malaria, whereas older and more educated caregivers are more likely to seek timely treatment for their children. To enhance health outcomes in this vulnerable group, targeted interventions should prioritize raising awareness among caregivers, particularly younger ones and prompting equitable care seeking to all children regardless of sex.

Current Developments in Malaria Vaccination: A Concise Review on Implementation, Challenges, and Future Directions

Introduction

Malaria remains a persistent challenge in global health, disproportionately affecting populations in endemic regions (eg, sub-Saharan Africa). Despite decades of international collaborative efforts, malaria continues to claim hundreds of thousands of lives each year, with young children and pregnant women enduring the heaviest burden. This concise review aimed to provide an up-to-date assessment of malaria vaccines progress, challenges, and future directions.

Methods

A PubMed/MEDLINE search (2015-2024) was conducted to identify studies on malaria vaccine development, implementation barriers, efficacy, and vaccination hesitancy. Clinical trials, reviews, and global health reports were included based on relevance to the review aims. No strict inclusion criteria were applied, and selection was guided by key review themes and policy relevance.

Results

The introduction of pre-erythrocytic malaria vaccines (RTS,S/AS01 and R21/Matrix-M), represents an important milestone in malaria control efforts with promising results from the erythrocytic vaccine RH5.1/Matrix-M in recent clinical trials. However, the approval of these vaccines is accompanied by significant challenges such as the limited efficacy, the complexity of multi-dose regimens, and numerous barriers to widespread implementation in resource-limited settings. The review identified the complex challenges to broad malaria vaccination coverage, including logistical barriers, healthcare infrastructure effect, financial limitations, malaria vaccine hesitancy, among other obstacles in malaria-endemic regions. Promising developments in malaria vaccination, such as next-generation candidates (eg, mRNA-based vaccines), hold the potential to offer improved efficacy, longer-lasting protection, and greater scalability. There is a critical need to integrate malaria vaccination efforts with established malaria control interventions (eg, insecticide-treated bed nets, vector control strategies, and anti-malarial drugs).

Conclusion

Achieving sustained control of malaria morbidity and mortality will require strong global collaboration, sufficient funding, and continuous efforts to address inequities in access and delivery of malaria control measures including the malaria vaccines.

Health Service-Related Determinants of Health-Seeking Behavior during Malaria Fever in a High-Risk Region of Nepal

Background and Aims

Malaria continues to be a significant global health challenge, leading to preventable illnesses and loss of lives. This cross-sectional descriptive study, employing a mixed-method approach, aimed to investigate the health service-related factors affecting health-seeking behavior during episodes of malaria fever in a high-risk region of Nepal.

Methods

Using a cross-sectional descriptive design with a mixed-method approach, the research focused on Kanchanpur district, selected from 20 high-risk malaria districts of Nepal. Belauri Municipality within Kanchanpur, identified for its concentration of high and moderate-risk wards, was the specific study area. A random selection process identified 387 households for a comprehensive survey. Face-to-face interviews with household heads were conducted after obtaining written informed consent and ethical approval from the Nepal Health Research Council. Data analysis, employing statistical measures such as percentages, frequency, mean, and the Chi-square test, was performed using SPSS version 20.

Results

Means of reaching the public health facility (AOR = 8.324, 95% CI = 3.677-18.844, p < 0.001), time to reach public health facility (AOR = 0.234, 95% CI = 0.059-0.918, p = 0.017), regular availability of service providers (AOR = 0.155, 95% CI = 0.054-0.442, p < 0.001), most of the time availability of service provider (AOR = 0.115, 95% CI = 0.039-0.334, p < 0.001), opening hours of health facility (AOR = 0.301, 95% CI = 0.156-0.581, p < 0.001), and perceived quality of service (AOR = 0.256, 95% CI = 0.154-0.424, p < 0.001), having to pay for transportation (COR = 0.275, 95% CI = 0.164-0.461, p < 0.001), travel cost (COR = 0.744, 95% CI = 0.640-0.865, p < 0.001), were the significant factors in health-seeking behavior during malaria fever.

Conclusion

Collectively, these findings provide a comprehensive understanding of the multifaceted nature of health-seeking behavior in the context of malaria fever and emphasize the importance of addressing various factors to improve healthcare utilization. Subsidized transportation for the poor helps to overcome financial barriers, establish additional facilities or mobile clinics to reduce travel time, ensure healthcare workforce availability, extend health facility hours, patient-centered initiatives to enhance service quality can increase the likelihood of people seeking care from modern health facilities in Nepal.

Computational Analysis of Plasmodium falciparum DNA Damage Inducible Protein 1 (PfDdi1): Insights into Binding of Artemisinin and its Derivatives and Implications for Antimalarial Drug Design

Human malaria remains a global health challenge, with Plasmodium falciparum responsible for the most severe cases. Despite global efforts, eradicating malaria has proven difficult, mainly because of the rise in drug resistance, particularly against artemisinin and its derivatives. One possible cause of this resistance is the activation of the unfolded protein response (UPR), which helps maintain cellular balance under stress. In P. falciparum, the UPR operates through the ubiquitin-proteasome system (UPS), which involves proteins such as Dsk2, Rad23, and Ddi1. Among these, Plasmodium falciparum DNA-damage-inducible protein 1 (PfDdi1) plays a crucial role in DNA repair and is present throughout the parasite life cycle, making it an attractive drug target. However, there is limited research on PfDdi1 as a therapeutic target. Recent in vitro studies have indicated that artemisinin (ART) and dihydroartemisinin (DHA) inhibit PfDdi1 activity. Building on this, we investigated whether ART and its derivatives could serve as inhibitors of PfDdi1 using computational modeling. Our study included clinically relevant ART derivatives such as artemether (ARM), arteether (AET), artemiside (AMD), and artesunate (ATS). All these compounds showed strong binding to PfDdi1, with free binding energies ranging from -20.75 kcal/mol for AET to -34.24 kcal/mol for ATS. ARM increased PfDdi1's structural rigidity and hydrophobic stability, whereas AMD improved its kinetic stability, resulting in the least residue motion. Unlike AET and AMD, the other ligands destabilize the PfDdi1 structure. Importantly, three key binding regions-Loop 1 (GLN 266 - ILE 269), Loop 2 (ILE 323 - TYR 326), and Loop 3 (ALA 292 - GLY 294)-were identified as potential targets for new antimalarial drugs against PfDdi1. This study highlights the potential of ART derivatives as PfDdi1 inhibitors, paving the way for further experimental validation.

Prevalence and determinants of insecticide-treated net ownership among women of reproductive age in Nigeria: a mixed-effect insight from the 2021 malaria indicator survey

BACKGROUND

Malaria continues to be a significant public health issue in Nigeria, which bears the highest burden of the disease globally. This study examined the prevalence and determinants of insecticide-treated net (ITN) ownership among women of reproductive age in Nigeria.

METHODS

The individual woman questionnaire data from the 2021 Nigeria Malaria Indicator Survey (NMIS) was used. In total, 14,476 women of reproductive age (15-49 years) made up the study's sample that was analysed. The outcome variable in the study was ITN ownership. Percentage and multivariable multilevel binary logistic regression model were estimated at p < 0.05.

RESULTS

The weighted prevalence of ITN ownership was 62.6% (95% CI 60.6-64.7%). Women aged 25-34 and 35-49 had 12% (aOR = 0.88; 95% CI 0.78-0.98) and 16% (aOR = 0.84; 95% CI 0.74-0.97) reduction in ITN ownership, when compared with women aged 15-24 years. Women who had 1-2 (aOR = 1.13; 95% CI 1.00-1.28), 3-4 (aOR = 1.28; 95% CI 1.11-1.46) and 5 and above living children (aOR = 1.35; 95% CI 1.15-1.58), had higher odds of ITN ownership when compared with those with no living child respectively. Women from non-poor households had higher odds of ITN ownership, when compared with their poor counterparts (aOR = 1.30; 95% CI 1.14-1.49). Women from North East (aOR = 4.52; 95% CI 3.08-6.63) and North West (aOR = 4.18; 95% CI 2.90-6.01) had higher odds of ITN ownership, while those from South East (aOR = 0.40; 95% CI 0.26-0.62) and South South (aOR = 0.59; 95% CI 0.41-0.85) had reductions in the odds of ITN ownership, when compared with women from North Central respectively.

CONCLUSION

Approximately two-third of Nigerian women reported ITN ownership. This underscore the need for targeted interventions to address barriers and improve ITN access. While free ITN distribution programmes have been effective, socioeconomic and demographic factors have remained contributory to ITN access. Enhanced strategies should focus on equitable distribution and improved access to ITN among groups to achieve better malaria control outcomes in Nigeria.

Changing Plasmodium falciparum malaria prevalence in two villages of northeastern Tanzania between 2003 and 2021 in relation to vectors, interventions and climatic factors

BACKGROUND

Malaria, which affects over half of the world's population, is controlled through clinical interventions and vector control strategies. However, these efforts are threatened by resistance to anti-malarial drugs and insecticides, as well as affected by environmental, ecological, and climatic changes. This study examined changes in malaria prevalence and related factors based on data from 18 cross-sectional surveys conducted in two villages in northeastern Tanzania.

METHODS

From 2003 to 2021, annual cross-sectional malariometric surveys were conducted in two study villages, Mkokola (lowland) and Kwamasimba (highland), samples collected to determine Plasmodium falciparum infection and human exposure to malaria vector Anopheles. Pearson's chi-squared test was used for comparing proportions, logistic and linear regressions test were used analyse associations. Generalized Estimating Equations (GEE) was used to analyse the relationship between malaria prevalence and climatic variables.

RESULTS

Malaria prevalence in Kwamasimba and Mkokola dropped from ~ 25% and ~ 80% to 0% and 1%, respectively, between 2003 and 2011, reaching 0% in both villages by 2014. This decline was associated with increased bed net use and reduced exposure to Anopheles bites. However, between 2018 and 2021, prevalence resurged, with Kwamasimba reaching 2003-2004 levels despite high bed net use. Between 2003 and 2021 there was an increasing trend in average monthly maximum temperatures (R2 = 0.1253 and 0.2005), and precipitation (R2 = 0.125 and 0.110) as well as minimum relative humidity (R2 = 0.141 and 0.1162) in Kwamasimba and Mkokola villages, respectively, while maximum relative humidity slightly decreased. Furthermore, during 2003-2011, malaria prevalence was positively associated with temperature, maximum temperature, and relative humidity, while precipitation showed a negative association (Estimate:- 0.0005, p < 0.001). Between 2012-2021, all climatic factors, including temperature (Estimate: 0.0256, p < 0.001), maximum temperature (Estimate: 0.0121, p < 0.001), relative humidity (Estimate: 0.00829, p < 0.001), and precipitation (Estimate: 0.000105, p < 0.001), showed positive associations.

CONCLUSION

From 2003 to 2014, malaria prevalence declined in two Tanzanian villages but resurged after 2018, particularly in highland Kwamasimba. Most likely, vector dynamics affected by changing climatic conditions drove this resurgence, emphasizing the need for adaptive, climate-informed malaria control strategies.

Molecular modeling of the interactions of compounds of Irvinga wombulu against dihydrofolate reductase-thymidylate synthase in Plasmodium falciparum towards development of anti-malarial drug

Malaria is a significant global health burden that affects the majority of people in the world. Nigeria still accounts for the highest percentage of the worldwide malaria burden, with 27% of estimated malaria cases and 31% of estimated deaths due to malaria in 2022. While antimalarial effects have been attributed to some active compounds from medicinal plants, no study has been conducted on Irvingia wombulu (IW). Therefore, this study aimed to evaluate the in silico antimalarial activity of some active compounds identified after gas chromatography/mass spectrometry (GC/MS) studies on Irvingia wombolu. The compounds were docked against the anti-malaria target Dihydrofolate Reductase-Thymidylate Synthase (DHFR-TS) of Plasmodium falciparum with PDB ID 3QGT and their pharmacokinetic properties were also predicted. This was followed by a molecular dynamics (MD) simulation of the protein in complex with the most promising IW compound. The GC-MS result revealed 44 phytoconstituents from IW. The Docking analysis revealed the following best binding energies (kcal/mol): alpha-tocopherol-beta-D-mannoside (-11.289), gamma-tocopherol (- 7.308), and linolenic acid (- 6.822). MD Simulation showed that the selected compound exhibited a stable conformation in the active site of the flexible protein. Pharmacokinetics analysis suggested that the compounds will be orally bio-available when administered. Therefore, these results indicate that these compounds can be considered for experimental validation and further development into antimalarial drugs.

Estimating Survival Functions in Children With Malaria in South Sudan: A Comparative Analysis of Associated Factors

INTRODUCTION

Malaria remains one of the major health problems worldwide. It is a leading cause of morbidity and mortality in South Sudan, especially in children. The aim of this study was to estimate the survival functions of children with malaria and to compare these functions with respect to the associated factors.

METHODS

This was a retrospective cohort study that utilized data extracted from records of children aged 1 month to 15 years who were diagnosed with malaria and admitted to Al Sabah Children's Hospital, Juba, South Sudan from 1 January to 31 December 2021. Kaplan-Meier was employed to estimate the survival functions, and the log-rank test statistic was used to compare survival curves with respect to categories of specific covariates.

RESULTS

Out of 6,410 children diagnosed with malaria who were included in this study, 3,595 (56.08%) were males and 2815 (43.92%) were females. A total of 303 (4.73%) died and 6,107 (95.27%) were censored. The median survival time was three days (IQR 2-4), and the mean age of the study cohort was 23.66 months (95% CI: 23.01 to 24.32). Comorbidity status among children indicated that 1,552 (24.01%) had comorbidities during admission. With respect to the treatment covariate, 3,920 (61.15%) were treated with artesunate. Kaplan-Meier survival curves showed increased survival for children treated with quinine and those without comorbidity. The log-rank test revealed that the covariates treatment and comorbidity were significant (p < 0.05), both having an impact on survival among children.

CONCLUSION

 This study found that the median survival time for children with malaria was three days. Additionally, comorbidity decreased survival among children. Treatment with quinine showed better survival rates compared to artesunate, despite studies suggesting artesunate as a replacement for quinine. Strengthening the healthcare system, provision of good-quality drugs, and implementing control intervention measures to reduce the transmission of malaria are essential for improving child survival in the country. Furthermore, it is essential to carry out a comparative study of quinine and artesunate for the treatment of malaria. Future studies on malaria in South Sudan have to be conducted by using a prospective study design to address the challenges of incomplete data and potential biases.

YAT2150 is irresistible in Plasmodium falciparum and active against Plasmodium vivax and Leishmania clinical isolates

We recently characterized the potent antiplasmodial activity of the aggregated protein dye YAT2150, whose presumed mode of action is the inhibition of protein aggregation in the malaria parasite. Using single-dose and ramping methods, assays were done to select Plasmodium falciparum parasites resistant to YAT2150 concentrations ranging from 3× to 0.25× the in vitro IC50 of the compound (in the two-digit nM range) and performed a cross-resistance assessment in P. falciparum lines harboring mutations that make them resistant to a variety of antimalarial drugs. Resistant parasites did not emerge in vitro after 60 days of incubation, which postulates YAT2150 as an 'irresistible' antimalarial. The lyophilized compound is stable for at least one year stored at 25 °C. Tests performed in clinical isolates indicated that YAT2150 had also strong activity against Plasmodium vivax (IC50 between 4 and 36 nM) and Leishmania infantum (1.27 and 1.11 µM), placing it as a unique compound with perspectives of becoming the first drug to be used against both malaria and leishmaniasis.

Caregiver acceptability of seasonal malaria chemoprevention in two districts in the Upper West region, Ghana: a cross-sectional study

BACKGROUND

Acceptability of malaria chemoprevention interventions by caregivers is crucial for overall programme success. This study assessed coverage and acceptability of Seasonal Malaria Chemoprevention (SMC) in selected communities in the Northern part of Ghana.

METHODS

An analytical cross-sectional design was conducted from "July 23rd to August 4th, 2020-a 12-day period that covered 5 days of the first SMC implementation cycle and 7 days post-implementation. Using a stratified multi-stage sampling technique, a total of 495 caregivers providing care for 569 eligible children aged 3-59 months from randomly selected households in the study communities were enrolled into the study. Acceptability of SMC was assessed on a set of 19 questionnaire items-8 of the items measured caregivers' perceptions and 11 items measured children's reaction to administered medicines. Univariable and stepwise multivariable logistic regression analyses were performed to assess the predictors of acceptability of SMC at a 95% confidence interval and a p-value of 0.05.

RESULTS

SMC coverage was 95.1% (541/569). Caregivers had a good level of knowledge of SMC (n = 475; 96.0%; 95% CI 94.2-97.7%) and a good perception of SMC (n = 471; 95.2%; 95% CI 93.3-97.0). Seven out of ten caregivers (70.9%; 95% CI 66.9-74.9%) had good acceptability of SMC. For 7 out of 28 children who did not receive the SMC intervention, their caregivers intentionally refused them the intervention. Of those that received the treatment, 17.2% (n = 85; 95%CI 13.8-20.5%) of caregivers had at least one leftover amodiaquine tablet after the third day of treatment. Caregivers who practice Christianity or Islam had better acceptability than caregivers who practice African traditional religion (p < 0.001).

CONCLUSION

Health authorities and stakeholders can work towards bridging the gap between knowledge and SMC treatment practices of caregivers through continuous education, adherence counseling, and effective monitoring of SMC practices in malaria-endemic countries.

Antimalarial Drug Discovery from Natural and Synthetic Sources

Malaria remains a significant global health threat despite extensive efforts aimed at its eradication. Numerous challenges persist in eliminating the disease, chief among them being the parasite's ability to mutate, resulting in drug resistance. The discovery of antimalarial drugs has relied on both phenotypic and target-based approaches. While phenotypic screening has identified promising candidates, target-based methods offer a more precise approach by leveraging chemically validated targets and computational tools. Analysis of Plasmodium spp . protein structures reveal druggable targets, offering opportunities for in silico screening. Combining compounds from natural and synthetic sources in a target-based approach accelerates the discovery of new antimalarial agents. This review explores previous breakthroughs in antimalarial drug discovery from natural products and synthetic origins, emphasizing their specific target proteins within Plasmodium species.

Designing and deploying caller tunes on mobile phones to promote malaria vaccine uptake in Africa: can the technology acceptance model (TAM) help?

Malaria remains a significant global health challenge, with millions of cases and high mortality rates annually, especially in low-income countries. Africa bears a substantial burden, with direct costs of malaria among children under five reaching millions of dollars in countries like Ghana, Tanzania, and Kenya. In 2021, over 610,000 malaria-related deaths were reported, 96% of which occurred in sub-Saharan Africa. Despite existing interventions, such as long-lasting insecticidal nets, indoor residual spraying, and intermittent preventive treatment, the re-emergence of malaria underscores the need for innovative preventive strategies. This study explores the potential of utilizing mobile phone caller tunes to raise awareness and promote the uptake of the RTS,S malaria vaccine. The technology acceptance model (TAM) provides a framework for understanding how users perceive and adopt new technologies. Caller tunes, a mobile phone feature that plays audio for callers waiting to be connected, have been effective in health communication campaigns in Asia and Africa. This approach could be leveraged to enhance malaria vaccine awareness, particularly in low-income countries where vaccine hesitancy is prevalent and malaria endemic. Overall, mobile technologies have significantly improved healthcare delivery in Africa, facilitating communication, monitoring, and treatment adherence in remote areas. Integrating caller tunes with health messages about the malaria vaccine could address vaccine hesitancy and improve uptake. This would require collaboration with telecommunication companies, healthcare providers, and policymakers to design culturally and linguistically appropriate messages. However, the cost of caller tune services, the need for internet access, and cultural differences are the expected challenge that may occur in this approach. Therefore, strategic partnerships and intersectoral approaches can mitigate these issues, making caller tunes a viable tool for public health communication. Raising awareness through this innovative method could enhance the adoption of the RTS,S vaccine and support ongoing malaria control efforts in Africa.

On the necessity of accounting for age structure in human malaria transmission modeling

Malaria is one of the most common mosquito-borne diseases widespread in tropical and subtropical regions, causing thousands of deaths every year in the world. In a previous paper, we formulated an age-structured model containing three structural variables: (i) the chronological age of human and mosquito populations, (ii) the time since they are infected, and (iii) humans waning immunity (i.e. the progressive loss of protective antibodies after recovery). In the present paper, we expand the analysis of this age-structured model and focus on the derivation of entomological and epidemiological results commonly used in the literature, following the works of Smith and McKenzie. We generalize their results to the age-structured case. In order to quantify the impact of neglecting structuring variables such as chronological age, we assigned values from the literature to our model parameters. While some parameters values are readily accessible from the literature, at least those about the human population, the parameters concerning mosquitoes are less commonly documented and the values of a number of them (e.g. mosquito survival in the presence or in absence of infection) can be discussed extensively. Our analysis, informed by parameter values from the literature, demonstrates that overlooking those structural variables of human and mosquito populations may result in inaccurate epidemiological predictions and suboptimal control strategies. We highlight the epidemiological implications of these findings and emphasize the necessity of considering age structure in future malaria control programs.

A study on the effectiveness of (+)-usnic acid as oral toxic sugar bait against adult male and female Anopheles gambiae

BACKGROUND

Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of ( +)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait.

METHODS

( +)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the ( +)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3).

RESULTS

There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml ( +)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed.

CONCLUSIONS

The results of this study indicate that ( +)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. ( +)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa.

Identification of natural inhibitors targeting trehalase of Anopheles funestus in the management of malaria: A Biocomputational assessment

BACKGROUND OBJECTIVES

Anopheles funestus is playing an increasingly important role in malaria transmission in sub-Saharan Africa. Trehalase, an enzyme required for trehalose breakdown, is important for mosquito flight and stress adaptation. Hence, its inhibition has emerged as a promising malaria management strategy.

METHODS

A collection of 1900 natural compounds from the ZINC database were screened against the 3D modeled structure of An. funestus trehalase protein using in silico tools. ADMET-AI, a web-based platform, was used to predict the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of the selected compounds.

RESULTS

We report 5 natural compounds namely, ZINC00488388, ZINC00488525, ZINC00488566, ZINC00488304, and ZINC00488456 that demonstrated strong binding affinity to the trehalase protein. These compounds interacted with critical residues of the trehalase protein and exhibited good drug-like characteristics.

INTERPRETATION CONCLUSION

These compounds show promise as trehalase protein inhibitors for malaria management. Nonetheless, additional experimental studies are required to optimize these compounds as potential trehalase inhibitors.

Variation in spatial population structure in the Anopheles gambiae species complex

Anopheles gambiae, Anopheles coluzzii, and Anopheles arabiensis are three of the most widespread vectors of malaria parasites, with geographical ranges stretching across wide swaths of Africa. Understanding the population structure of these closely related species, including the extent to which populations are connected by gene flow, is essential for understanding how vector control implemented in one location might indirectly affect vector populations in other locations. Here, we assessed the population structure of each species based on a combined data set of publicly available and newly processed whole-genome sequences. The data set included single nucleotide polymorphisms from whole genomes of 2,410 individual mosquitoes sampled from 128 locations across 19 African countries. We found that A. gambiae sampled from several countries in West and Central Africa showed low genetic differentiation from each other according to principal components analysis (PCA) and ADMIXTURE modeling. Using Estimated Effective Migration Surfaces (EEMS), we showed that this low genetic differentiation indicates high effective migration rates for A. gambiae across this region. Outside of this region, we found eight groups of sampling locations from Central, East, and Southern Africa for which A. gambiae showed higher genetic differentiation, and lower effective migration rates, between each other and the West/Central Africa group. These results indicate that the barriers to and corridors for migration between populations of A. gambiae differ across the geographical range of this malaria vector species. Using the same methods, we found higher genetic differentiation and lower migration rates between populations of A. coluzzii in West and Central Africa than for A. gambiae in the same region. In contrast, we found lower genetic differentiation and higher migration rates between populations of A. arabiensis in Tanzania, compared to A. gambiae in the same region. These differences between A. gambiae, A. coluzzii, and A. arabiensis indicate that migration barriers and corridors may vary, even between very closely related species. Overall, our results demonstrate that migration rates vary both within and between species of Anopheles mosquitoes, presumably based on species-specific responses to the ecological or environmental conditions that may impede or facilitate migration, and the geographical patterns of these conditions across the landscape. Together with previous findings, this study provides robust evidence that migration rates between populations of malaria vectors depend on the ecological context, which should be considered when planning surveillance of vector populations, monitoring for insecticide resistance, and evaluating interventions.

Unveiling the significance of women's role in health-seeking behavior during suspected malaria fever in risk populations of Nepal: Mixed methods cross-sectional study

Malaria remains a substantial global health challenge, causing preventable illnesses and fatalities. In Nepal, the government has ambitiously targeted achieving malaria-free status by 2025. This study aims to assess the impact of women's roles on health-seeking behavior during suspected malaria fever in the high-risk area of Kanchanpur district, Nepal. This is a cross-sectional analytical design with a mixed-method approach, the research focused on Kanchanpur district, selected from 20 high-risk malaria districts of Nepal. Belauri Municipality within Kanchanpur, identified for its concentration of high and moderate-risk wards, was the specific study area. A random selection process identified 387 households for a comprehensive survey. Face-to-face interviews with household heads were conducted after obtaining written informed consent and ethical approval from the Nepal Health Research Council (March 3, 2023/Ref no.-2041). Data analysis, employing statistical measures such as percentages, frequency, mean, and the Chi-square test, was performed using SPSS version 20. Cultural beliefs regarding women's use of bed nets during menstruation significantly predicted health-seeking behavior (p-value < 0.05). Those endorsing bed net use during menstruation were nearly twice as likely to choose modern health facilities (COR = 1.975, 95% C.I. = 1.134 to 3.439, p = 0.016). Women's involvement in malaria treatment decisions strongly correlated with health-seeking behavior (p-value = 0.001). However, women participating in household decisions for suspected malaria treatment were less likely to choose modern health facilities (COR = 0.327, 95% CI = 0.171-0.627, p = 0.001) compared to those without such a role. The study underscores the complex influence of cultural beliefs and women's decision-making roles on health-seeking behavior. Recognizing and comprehending these factors are vital for crafting effective malaria interventions that align with cultural contexts and consider the nuanced roles of women in health-related decisions.

Semi-field evaluation of aquatic predators for the control of Anopheles funestus in rural south-eastern Tanzania

BACKGROUND

Biological control is a promising alternative or complementary approach for controlling vector populations in response to the spread of insecticide resistance in malaria vectors. This study evaluated the efficacy of three selected potential predators on the density and fitness parameters of Anopheles funestus larvae in rural Tanzania.

METHODS

Common predator families Aeshnidae (dragonflies), Coenagrionidae (damselflies), and Notonectidae (backswimmers) and An. funestus group larvae were collected from natural aquatic habitats in rural south-eastern Tanzania. Predators were starved for 12-h while An. funestus larvae were given fish food before starting the experiment. Anopheles funestus larvae were placed into artificial habitats containing predators, exposing them to potential predation. The number of surviving An. funestus larvae were counted every 24-h. An emergence traps were placed at the top of artificial habitats to capture emerging mosquitoes. Emerged mosquitoes were monitored until they died. Female wings were measured and used as a proxy for body size. Generalized linear mixed models (GLMM) with binomial variates at 95% CI and Cox proportional hazard models were used to assess the proportion of dead mosquitoes and the daily survival determined.

RESULTS

There were significant differences in the number of emerged mosquitoes between the treatment and control groups (P < 0.001). Thus, all predator species played a significant role in reducing the density of An. funestus mosquitoes (P < 0.001). Furthermore, these predators had notable effects on the fitness parameters and survival of emerged mosquitoes (P < 0.001). Among the three predators studied, Coenagrionidae (damselflies) were most efficient followed by Notonectidae (backswimmers), with Aeshnidae (dragonflies) being the least efficient.

CONCLUSION

Selected aquatic predators have the potential to reduce the survival and density of An. funestus larvae. They might eventually be included within an integrated malaria vector control strategy, ultimately leading to a reduction in malaria transmission.

Rapid entomological assessment in eight high malaria endemic regencies in Papua Province revealed the presence of indoor and outdoor malaria transmissions

Malaria in eastern Indonesia remains high despite significant reduction and elimination in other parts of the country. A rapid entomological assessment was conducted in eight high malaria endemic regencies of Papua Province, Indonesia, to expedite malaria elimination efforts in this region. This study aims to characterize specific, actionable endpoints toward understanding where and when malaria transmission is happening, where interventions may function best, and identify gaps in protection that result in continued transmission. The entomological assessment included identifying potential vectors through human landing catch (HLC), indoor morning and night resting collections, identification of larval sites through surveillance of water bodies, and vector incrimination toward understanding exposure to malaria transmission. Human landing catches (HLCs) and larval collections identified 10 Anopheles species, namely Anopheles koliensis, Anopheles punctulatus, Anopheles farauti, Anopheles hinesorum, Anopheles longirostris, Anopheles peditaeniatus, Anopheles tesselatus, Anopheles vagus, Anopheles subpictus and Anopheles kochi. The most common and abundant species found overall were An. koliensis and An. punctulatus, while An. farauti was found in large numbers in the coastal areas of Mimika and Sarmi Regencies. Vector incrimination on Anopheles collected from HLCs and night indoor resting demonstrated that An. koliensis and An. punctulatus carried Plasmodium in Keerom, Jayapura, and Sarmi Regencies. Analysis of HLCs for the most common species revealed that the An. koliensis and An. punctulatus, bite indoors and outdoors at equal rates, while An. farauti predominantly bite outdoors. Larval surveillance demonstrated that most water bodies in and surrounding residential areas contained Anopheles larvae. This study demonstrated indoor and outdoor exposure to mosquito bites and gaps in protection, enabling exposure to infectious bites in all regencies. This explains why current malaria control efforts focusing on indoor protection have failed to substantially reduce malaria incidence in the region. Optimization of insecticide-treated bed nets (ITNs), as well as installment of mosquito screens in houses, may further reduce indoor transmission. For outdoor transmission, the use of community-centric approaches to reduce or eliminate larval sources within and surrounding the village through the guidance of locally stationed entomologists, along with Social and Behavior Change mediated health education towards the local adoption of mosquito protection tools during outdoor activities, may reduce malaria transmission.

Bio-efficacy of Olyset® Plus, PermaNet® 3.0 and Interceptor® G2 on pyrethroid-resistant populations of Anopheles gambiae s.l. prior to the June 2023 net distribution campaign in Benin, West Africa

BACKGROUND

This study investigates the effectiveness of new-generation mosquito nets, like Olyset® Plus and PermaNet® 3.0, and dual-action nets such as Interceptor® G2, against pyrethroid-resistant Anopheles gambiae mosquitoes following the 2023 mass distribution of long-lasting insecticidal nets in Benin.

METHODS

We tested wild mosquito populations from six communes in Benin against various pyrethroid (permethrin 0.75%, alphacypermethrin 0.05%, and deltamethrin 0.05%) using WHO tube tests. Additionally, we exposed mosquitoes to chlorfenapyr 100 µg/ml using the CDC bottle bioassay method. A subset of mosquitoes underwent biochemical and PCR tests to check the overexpression of metabolic enzymes and the Kdr L1014F mutation. We evaluated the effectiveness of Olyset® Plus, PermaNet® 3.0, and Interceptor® G2 nets using cone and tunnel tests on both laboratory and field populations of An. gambiae.

RESULTS

Overall, the highest mortality rate was 60% with pyrethroid and 98 to100% with chlorfenapyr. In cone tests, all three types of nets induced mortality rates above 80% in the susceptible laboratory strain of An. gambiae. Notably, Olyset® Plus showed the highest mortality rates for pyrethroid-resistant mosquitoes in cone tests, ranging from 81.03% (95% CI: 68.59-90.13) in Djougou to 96.08% (95% CI: 86.54-99.52) in Akpro-Missérété. PermaNet® 3.0 had variable rates, from 42.5% (95% CI: 27.04-59.11) in Djougou to 58.54% (95% CI: 42.11-73.68) in Porto-Novo. However, revealed good results for Interceptor® G2, with 94% (95% CI: 87.40-97.77) mortality and 89.09% blood sampling inhibition in local populations of An. gambiae. In comparison, Interceptor® had lower rates of 17% (95% CI: 10.23-25.82) and 60%, respectively.

CONCLUSION

These results suggest that tunnel tests are effective for evaluating dual-active ingredient nets. Additionally, Interceptor® G2 and PBO nets like Olyset® Plus could be considered as alternatives against pyrethroid-resistant mosquitoes.

The effect of explicit convection on simulated malaria transmission across Africa

Malaria transmission across sub-Saharan Africa is sensitive to rainfall and temperature. Whilst different malaria modelling techniques and climate simulations have been used to predict malaria transmission risk, most of these studies use coarse-resolution climate models. In these models convection, atmospheric vertical motion driven by instability gradients and responsible for heavy rainfall, is parameterised. Over the past decade enhanced computational capabilities have enabled the simulation of high-resolution continental-scale climates with an explicit representation of convection. In this study we use two malaria models, the Liverpool Malaria Model (LMM) and Vector-Borne Disease Community Model of the International Centre for Theoretical Physics (VECTRI), to investigate the effect of explicitly representing convection on simulated malaria transmission. The concluded impact of explicitly representing convection on simulated malaria transmission depends on the chosen malaria model and local climatic conditions. For instance, in the East African highlands, cooler temperatures when explicitly representing convection decreases LMM-predicted malaria transmission risk by approximately 55%, but has a negligible effect in VECTRI simulations. Even though explicitly representing convection improves rainfall characteristics, concluding that explicit convection improves simulated malaria transmission depends on the chosen metric and malaria model. For example, whilst we conclude improvements of 45% and 23% in root mean squared differences of the annual-mean reproduction number and entomological inoculation rate for VECTRI and the LMM respectively, bias-correcting mean climate conditions minimises these improvements. The projected impact of anthropogenic climate change on malaria incidence is also sensitive to the chosen malaria model and representation of convection. The LMM is relatively insensitive to future changes in precipitation intensity, whilst VECTRI predicts increased risk across the Sahel due to enhanced rainfall. We postulate that VECTRI's enhanced sensitivity to precipitation changes compared to the LMM is due to the inclusion of surface hydrology. Future research should continue assessing the effect of high-resolution climate modelling in impact-based forecasting.

Assessing the implementation fidelity, feasibility, and sustainability of community-based house improvement for malaria control in southern Malawi: a mixed-methods study

BACKGROUND

Despite significant success in the fight against malaria over the past two decades, malaria control programmes rely on only two insecticidal methods: indoor residual spraying and insecticidal-treated nets. House improvement (HI) can complement these interventions by reducing human-mosquito contact, thereby reinforcing the gains in disease reduction. This study assessed the implementation fidelity, which is the assessment of how closely an intervention aligns with its intended design, feasibility, and sustainability of community-led HI in southern Malawi.

METHODS

The study, conducted in 22 villages (2730 households), employed a mixed-methods approach. Implementation fidelity was assessed using a modified framework, with longitudinal surveys collecting data on HI coverage indicators. Quantitative analysis, employing descriptive statistics, evaluated the adherence to HI implementation. Qualitative data came from in-depth interviews, key informant interviews, and focus groups involving project beneficiaries and implementers. Qualitative data were analysed using content analysis guided by the implementation fidelity model to explore facilitators, challenges, and factors affecting intervention feasibility.

RESULTS

The results show that HI was implemented as planned. There was good adherence to the intended community-led HI design; however, the adherence could have been higher but gradually declined over time. In terms of intervention implementation, 74% of houses had attempted to have eaves closed in 2016-17 and 2017-18, compared to 70% in 2018-19. In 2016-17, 42% of houses had all four sides of the eaves closed, compared to 33% in 2018-19. Approximately 72% of houses were screened with gauze wire in 2016-17, compared to 57% in 2018-19. High costs, supply shortages, labour demands, volunteers' poor living conditions and adverse weather were reported to hinder the ideal HI implementation. Overall, the community described community-led HI as feasible and could be sustained by addressing these socioeconomic and contextual challenges.

CONCLUSION

Our study found that although HI was initially implemented as planned, its fidelity declined over time. Using trained volunteers facilitated the fidelity and feasibility of implementing the intervention. A combination of rigorous community education, consistent training, information, education and communication, and intervention modifications may be necessary to address the challenges and enhance the intervention's fidelity, feasibility, and sustainability.

NANOPARTICLE-BASED formulation of dihydroartemisinin-lumefantrine duo-drugs: Preclinical Evaluation and enhanced antimalarial efficacy in a mouse model

Artemisinin-based combinations (ACTs) are World Health Organization-recommended treatment for malaria. Artemether (A) and lumefantrine (LUM) were the first co-formulated ACT and first-line treatment for malaria globally, artemether is dihydroartemisinin's (DHA's) prodrug. Artemisinins and LUM face low aqueous solubility while artemisinin has low bioavailability and short half-life thus requiring continuous dosage to maintain adequate therapeutic drug-plasma concentration. This study aimed at improving ACTs limitations by nano-formulating DHA-LUM using solid lipid nanoparticles (SLNs) as nanocarrier. SLNs were prepared by modified solvent extraction method based on water-in-oil-in-water double emulsion. Mean particle size, polydispersity index and zeta potential were 308.4 nm, 0.29 and -16.0 mV respectively. Nanoencapsulation efficiencies and drug loading of DHA and LUM were 93.9%, 33.7%, 11.9%, and 24.10% respectively. Nanoparticles were spherically shaped and drugs followed Kors-Peppas release model, steadily released for over 72 h. DHA-LUM-SLNs were 31% more efficacious than conventional oral doses in clearing Plasmodium berghei from infected Swiss albino mice.

Methemoglobin levels in malaria: a systematic review and meta-analysis of its association with Plasmodium falciparum and Plasmodium vivax infections and disease severity

Reports indicate that Plasmodium infections influence methemoglobin levels. However, findings have been inconclusive or have varied across different geographic and demographic contexts. This systematic review and meta-analysis aimed to consolidate existing data regarding the association between Plasmodium infections and alterations in methemoglobin levels related to the severity of the infection. A comprehensive literature search of several databases, including Ovid, ProQuest, Embase, Scopus, MEDLINE, and PubMed, was conducted to identify relevant studies that examined methemoglobin levels in patients with malaria. Qualitative synthesis and meta-analysis of the pooled standardized mean difference were conducted to synthesize the differences in methemoglobin levels between: (1) patients with malaria and those without malaria and (2) patients with severe malaria and those with uncomplicated malaria based on various themes including publication year, study design, study area, Plasmodium species, age group, symptomatic status, severity status, and method of malaria detection. Of the 1846 studies that were initially identified from the main databases and additional searches on Google Scholar, 10 studies met the eligibility criteria and were selected for this review. The systematic review distinctly highlighted an association between malaria and elevated methemoglobin levels, an observation consistent across diverse geographical regions and various Plasmodium species. Furthermore, the meta-analysis confirmed this by demonstrating increased methemoglobin levels in patients with malaria compared to those without malaria (P < 0.001, Hedges' g 2.32, 95% CI 1.36-3.29, I2 97.27, 8 studies). Moreover, the meta-analysis found elevated methemoglobin levels in patients with severe malaria compared to those with uncomplicated malaria (P < 0.001, Hedges' g 2.20, 95% CI 0.82-3.58, I2 96.20, 5 studies). This systematic review and meta-analysis revealed increased methemoglobin levels in patients with P. falciparum and P. vivax infections, with a notable association between elevated methemoglobin levels and severe malaria. Future research should focus on elucidating the specific mechanisms by which changes in methemoglobin levels are related to infections by P. falciparum and P. vivax, particularly in terms of severity, and how these alterations could potentially impact patient management and treatment outcomes.

Epidemiological behaviour and interventions of malaria in Niger, 2010-2019: a time-series analysis of national surveillance data

BACKGROUND

Malaria remains a significant public health concern in Niger, with the number of cases increasing from 592,334 in 2000 to 3,138,696 in 2010. In response, a concerted campaign against the disease has been initiated. However, the implementation of these malaria interventions and their association with epidemiological behaviour remains unclear.

METHODS

A time-series study was conducted in Niger from 2010 to 2019. Multiple data sources concerning malaria were integrated, encompassing national surveillance data, Statistic Yearbook, targeted malaria control interventions, and meteorological data. Incidence rate, mortality rate, and case fatality ratio (CFR) by different regions and age groups were analysed. Joinpoint regression models were used to estimate annual changes in malaria. The changes in coverage of malaria interventions were evaluated.

RESULTS

Between 2010 to 2019, the incidence rate of malaria decreased from 249.43 to 187.00 cases per 1,000 population in Niger. Niamey had a high annual mean incidence rate and the lowest CFR, while Agadez was on the contrary. Joinpoint regression analysis revealed a declining trend in malaria incidence for all age groups except the 10-24 years group, and the mortality rate and the CFR initially decreased followed by an increase in all age groups. Niger has implemented a series of malaria interventions, with the major ones being scaled up to larger populations during the study period.

CONCLUSIONS

The scale-up of multi-interventions in Niger has significantly reduced malaria incidence, but the rise in mortality rate and CFR addresses the challenges in malaria control and elimination. Malaria endemic countries should enhance surveillance of malaria cases and drug resistance in Plasmodium, improve diagnosis and treatment, expand the population coverage of insecticide-treated bed nets and seasonal malaria chemoprevention, and strengthen the management of severe malaria cases.

Virtual Screening of Flavonoids against Plasmodium vivax Duffy Binding Protein Utilizing Molecular Docking and Molecular Dynamic Simulation

BACKGROUND

Plasmodium vivax (P. vivax) is one of the highly prevalent human malaria parasites. Due to the presence of extravascular reservoirs, P. vivax is extremely challenging to manage and eradicate. Traditionally, flavonoids have been widely used to combat various diseases. Recently, biflavonoids were discovered to be effective against Plasmodium falciparum.

METHODS

In this study, in silico approaches were utilized to inhibit Duffy binding protein (DBP), responsible for Plasmodium invasion into red blood cells (RBC). The interaction of flavonoid molecules with the Duffy antigen receptor for chemokines (DARC) binding site of DBP was investigated using a molecular docking approach. Furthermore, molecular dynamic simulation studies were carried out to study the stability of top-docked complexes.

RESULTS

The results showed the effectiveness of flavonoids, such as daidzein, genistein, kaempferol, and quercetin, in the DBP binding site. These flavonoids were found to bind in the active region of DBP. Furthermore, the stability of these four ligands was maintained throughout the 50 ns simulation, maintaining stable hydrogen bond formation with the active site residues of DBP.

CONCLUSION

The present study suggests that flavonoids might be good candidates and novel agents against DBP-mediated RBC invasion of P. vivax and can be further analyzed in in vitro studies.

Malaria treatment health seeking behaviors among international students at the University of Ghana Legon

INTRODUCTION

Appropriate management of malaria demands early health seeking behaviour upon suspicion of malaria-like symptoms. This study examined malaria treatment seeking behaviour and associated factors among international students at University of Ghana.

METHODS

The study used a cross-sectional and quantitative approach. Data collection was undertaken using a structured questionnaire administered on a random sample of 264 international students. Data obtained on malaria treatment and factors influencing treatment behaviors were analyzed using IBM, SPSS Statistics version 22. Associations between individual characteristics and Malaria treatment seeking behavior was assessed by Pearson Chi-square(X2) test of independence. Binary logistic regression model was built using a backwards Wald approach, with variables retained at Wald p-value <0.05.

RESULTS

The findings show that 35% of the respondents obtained self-prescribed antimalarial at their utmost first choice of Malaria treatment. At bivariate level, a significant relationship between Malaria health-care seeking behaviour and:- Respondents continent, X2(1, N = 264) = 7.936, p = .005; Service accessibility, X2(1, N = 264) = 7.624, p = .006; Wait time, X2(1, N = 264) = 22.514, p <0.001; Treatment cost, X2(1, N = 264) = 97.160, p <0.001; Health insurance, X2(1, N = 264) = 5.837, p = 0.016, and Perceived staff attitude, X2(1, N = 264) = 18.557, p < 0.001. At multivariable analysis, inappropriate malaria health seeking behaviours was associated with low perceived service accessibility as (≥30mins) (aOR = 6.67; p<0.001), perceived long wait time (≥30mins), (aOR = 5.94; p = 0.015), perceived treatment cost affordability (<15 GHC) (aOR = 19.88; p<0.001) and age group: -34-41years (aOR = 8.83; p<0.001).

CONCLUSION

There were widespread inappropriate health-care seeking behavior for Malaria treatment among international students. Improving accessibility to malaria treatment services, reducing wait time at health facilities and the treatment cost will address inappropriate malaria treatment health seeking behaviours among the international students.

Analysis of complementarities between nanomedicine and phytodrugs for the treatment of malarial infection

The use of nanocarriers in medicine, so-called nanomedicine, is one of the most innovative strategies for targeting drugs at the action site and increasing their activity index and effectiveness. Phytomedicine is the oldest traditional method used to treat human diseases and solve health problems. The recent literature on the treatment of malaria infections using nanodelivery systems and phytodrugs or supplements has been analyzed. For the first time, in the present review, a careful look at the considerable potential of nanomedicine in promoting phytotherapeutic efficacy was done, and its key role in addressing a translation through a significant reduction of the current burden of malaria in many parts of the world has been underlined.

Anti-malarial activity of the alkaloid, heptaphylline, and the furanocoumarin, imperatorin, from Clausena anisata against human Plasmodium falciparum malaria parasites: ex vivo trophozoitocidal, schizonticidal and gametocytocidal approach

BACKGROUND

The erythrocytic stage of the life cycle of the malaria parasite, Plasmodium falciparum, consists of trophozoite, schizont and gametocyte stages in humans. Various anti-malarial agents target different stages of the parasite to produce treatment outcomes. This study reports on the stage-specific anti-malarial activity of heptaphylline and imperatorin against human P. falciparum in addition to their cytotoxicity and selectivity indices (SI).

METHODS

The compounds were isolated from Clausena anisata using column chromatography and their structures elucidated using NMR spectroscopy. The anti-malarial activity was determined by measuring the trophozoitocidal, schizonticidal and gametocytocidal activities of the compounds using the SYBR green assay. Cytotoxicity was evaluated using the tetrazolium-based colorimetric assay.

RESULTS

Heptaphylline and imperatorin produced trophozoitocidal, schizonticidal and gametocytocidal activities with IC50s of 1.57 (0.2317)-26.92 (0.3144) µM with those of artesunate (the standard drug) being 0.00024 (0.0036)-0.0070 (0.0013) µM. In the cytotoxicity assay, the compounds produced CC50S greater than 350 µM and SI of 13.76-235.90. Also, the trophozoitocidal and schizonticidal activities of the compounds were more pronounced than their gametocytocidal activity. Imperatorin was 42.04% more trophozoitocidal than hepthaphyline. However, hepthaphyline has more schizonticidal and gametocytocidal properties than imperatorin.

CONCLUSION

Heptaphylline and imperatorin are promising anti-malarial agents, since they possess potent anti-malarial activity with weak cytotoxicity on RBCs. However, imperatorin is a better anti-malarial prophylactic agent whereas heptaphylline is a better malaria treatment agent.

Assessing the susceptibility and efficacy of traditional neurotoxic (pyrethroid) and new-generation insecticides (chlorfenapyr, clothianidin, and pyriproxyfen), on wild pyrethroid-resistant populations of Anopheles gambiae from southern Benin

BACKGROUND

The objective of this study was to determine the susceptibility of wild Anopheles gambiae sensu lato (s.l.) from southern Benin to the new insecticides (chlorfenapyr (CFP), pyriproxyfen (PPF), and clothianidin (CTD)) and assess the efficacy of insecticide-treated bed nets (ITNs) that contain these new products.

METHODS

Wild An. gambiae from the Benin communes of Allada, Ifangni, Akpro-Missérété, and Porto-Novo were tested for their susceptibility to CFP and PPF using the WHO bottle tests, and pyrethroids (alpha-cypermethrin, deltamethrin, and permethrin) and CTD using WHO tube tests. WHO cone tests were used to evaluate the efficacy of Interceptor® (which contains alpha-cypermethrin (ACM) only), Interceptor® G2, (CFP + ACM), and Royal Guard® nets (PPF + ACM). The ovaries of blood-fed An. gambiae from Ifangni exposed to a new PPF net were dissected, and egg development status was examined using Christopher's stages to determine the fertility status of the mosquitoes. Using a standardized protocol, the oviposition rate and oviposition inhibition rate were calculated from live blood-fed An. gambiae placed in oviposition chambers after exposure to PPF.

RESULTS

In all four mosquito populations, pyrethroid mortality ranged from 5 to 80%, while chlorfenapyr and clothianidin mortality ranged from 98 to 100%. At Ifangni, all mosquitoes exposed to Royal Guard® nets were infertile (100%) while the majority (74.9%) of mosquitoes exposed to Interceptor® nets had fully developed their eggs to Christopher's stage V. The oviposition inhibition rate after exposure of the mosquitoes to the PPF was 99% for the wild population of An. gambiae s.l. and the susceptible laboratory strain, An. gambiae sensu stricto (Kisumu).

CONCLUSIONS

The results of this study suggest that pyrethroid-resistant An. gambiae from the selected communes in southern Benin are susceptible to chlorfenapyr, clothianidin, and pyriproxyfen. In addition, based on bioassay results, new and unused Interceptor® G2 and Royal Guard® nets were effective on Ifangni's mosquito populations. Despite the availability of new effective insecticides, continued vigilance is needed in Benin. Therefore, monitoring of resistance to these insecticides will continue to periodically update the Benin national insecticide resistance database and management plan.

Baseline characterization of entomological drivers of malaria transmission in Namibia: a targeted operational entomological surveillance strategy

BACKGROUND

Namibia's focus on the elimination of malaria requires an evidence-based strategy directed at understanding and targeting the entomological drivers of malaria transmission. In 2018 and 2019, the Namibia National Vector-borne Diseases Control Program (NVDCP) implemented baseline entomological surveillance based on a question-based approach outlined in the Entomological Surveillance Planning Tool (ESPT). In the present study, we report on the findings of the ESPT-based NVDCP on baseline vector species composition and bionomic traits in malaria endemic regions in northern Namibia, which has the aim of generating an evidence base for programmatic decision-making.

METHODS

Nine representative sentinel sites were included in the 2018 entomological surveillance program (Kunene, Omusati, Oshana, Ohangwena, Oshikoto, Otjozondjupa, Kavango West, Kavango East and Zambezi); the number was reduced to four sites in 2019 due to limited funding (Ohangwena, Kavango West, Kavango East, and Zambezi). In the 2018 baseline collections, multiple sampling methods (human landing catches, pyrethroid spray catches, U.S. Centers for Disease Control and Prevention light traps [CDC-LTs], resting boxes [RBs] and larval sampling) were utilized to evaluate indoor/outdoor human biting rates, resting behaviors and insecticide resistance (IR). CDC-LTs and RBs were not used in 2019 due to low and non-representative sampling efficacies.

RESULTS

Overall, molecular evidence demonstrated the presence of three primary mosquito vectors, namely Anopheles arabiensis, rediscovered Anopheles gambiae sensu stricto and Anopheles funestus sensu stricto, alongside Anopheles squamosus and members of the Anopheles coustani complex. Vectors were found to bite throughout the night (1800 hours 0600 hours) both indoors and outdoors, with An. arabiensis having the highest biting rates outdoors. Low numbers of indoor resting Anopheles point to possible low indoor residual spraying (IRS) efficacy-with An. arabiensis found to be the major vector species resting indoors. The IR tests demonstrated varying country-wide resistance levels to the insecticide deltamethrin, with the resistance levels confirmed to have increased in 2019, evidence that impacts national programmatic decision-making. Vectors demonstrated susceptibility to the insecticides dichlorodiphenyltrichloroethane, bendiocarb and Actellic 300CS in 2018, with mosquitoes from only one site (Kavango West) demonstrating possible resistance to DDT. Targeted and question-based entomological surveillance enabled a rapid and focused evidence base to be built, showing where and when humans were being bitten and providing entomological data on long-lasting insecticidal nets, IRS efficacy and insecticide resistance, which the Ministry of Health and Social Services-Namibia can use to further build a monitoring and evaluation framework for understanding the drivers of transmission.

CONCLUSION

Identification and characterization of species-specific bionomic traits allows for an understanding of where and when vector human contact may occur as well as the potential impact of interventions. Low indoor resting rates as well as the presence of insecticide resistance (and the increase in its frequency) point to the need for mosquito-behavior-directed and appropriate interventions as well as the requirement for a resistance mitigation strategy. The ESPT-based question- and minimal essential indicator-based operational research strategy provides programs with directed and focused data for facilitating decision-making while requiring limited funding and capacity.

Computational Exploration of Licorice for Lead Compounds against Plasmodium vivax Duffy Binding Protein Utilizing Molecular Docking and Molecular Dynamic Simulation

Plasmodium vivax (P. vivax) is one of the human's most common malaria parasites. P. vivax is exceedingly difficult to control and eliminate due to the existence of extravascular reservoirs and recurring infections from latent liver stages. Traditionally, licorice compounds have been widely investigated against viral and infectious diseases and exhibit some promising results to combat these diseases. In the present study, computational approaches are utilized to study the effect of licorice compounds against P. vivax Duffy binding protein (DBP) to inhibit the malarial invasion to human red blood cells (RBCs). The main focus is to block the DBP binding site to Duffy antigen receptor chemokines (DARC) of RBC to restrict the formation of the DBP-DARC complex. A molecular docking study was performed to analyze the interaction of licorice compounds with the DARC binding site of DBP. Furthermore, the triplicates of molecular dynamic simulation studies for 100 ns were carried out to study the stability of representative docked complexes. The leading compounds such as licochalcone A, echinatin, and licochalcone B manifest competitive results against DBP. The blockage of the active region of DBP resulting from these compounds was maintained throughout the triplicates of 100 ns molecular dynamic (MD) simulation, maintaining stable hydrogen bond formation with the active site residues of DBP. Therefore, the present study suggests that licorice compounds might be good candidates for novel agents against DBP-mediated RBC invasion of P. vivax.

A Critical Review on Human Malaria and Schistosomiasis Vaccines: Current State, Recent Advancements, and Developments

Malaria and schistosomiasis are two major parasitic diseases that remain leading causes of morbidity and mortality worldwide. Co-infections of these two parasites are common in the tropics, where both diseases are endemic. The clinical consequences of schistosomiasis and malaria are determined by a variety of host, parasitic, and environmental variables. Chronic schistosomiasis causes malnutrition and cognitive impairments in children, while malaria can cause fatal acute infections. There are effective drugs available to treat malaria and schistosomiasis. However, the occurrence of allelic polymorphisms and the rapid selection of parasites with genetic mutations can confer reduced susceptibility and lead to the emergence of drug resistance. Moreover, the successful elimination and complete management of these parasites are difficult due to the lack of effective vaccines against Plasmodium and Schistosoma infections. Therefore, it is important to highlight all current vaccine candidates undergoing clinical trials, such as pre-erythrocytic and erythrocytic stage malaria, as well as a next-generation RTS,S-like vaccine, the R21/Matrix-M vaccine, that conferred 77% protection against clinical malaria in a Phase 2b trial. Moreover, this review also discusses the progress and development of schistosomiasis vaccines. Furthermore, significant information is provided through this review on the effectiveness and progress of schistosomiasis vaccines currently under clinical trials, such as Sh28GST, Sm-14, and Sm-p80. Overall, this review provides insights into recent progress in malarial and schistosomiasis vaccines and their developmental approaches.

Drug Development Strategies for Malaria: With the Hope for New Antimalarial Drug Discovery—An Update

Malaria continued to be a deadly situation for the people of tropical and subtropical countries. Although there has been a marked reduction in new cases as well as mortality and morbidity rates in the last two decades, the reporting of malaria caused 247 million cases and 619000 deaths worldwide in 2021, according to the WHO (2022). The development of drug resistance and declining efficacy against most of the antimalarial drugs/combination in current clinical practice is a big challenge for the scientific community, and in the absence of an effective vaccine, the problem becomes worse. Experts from various research organizations worldwide are continuously working hard to stop this disaster by employing several strategies for the development of new antimalarial drugs/combinations. The current review focuses on the history of antimalarial drug discovery and the advantages, loopholes, and opportunities associated with the common strategies being followed for antimalarial drug development.

An in silico quest for next-generation antimalarial drugs by targeting Plasmodium falciparum hexose transporter protein: a multi-pronged approach

The emergence of artemisinin resistance by malaria parasites is a major challenge in the fight against malaria, thus posing serious threat to the public health across the world. To tackle this, antimalarial drugs with unconventional mechanisms are therefore urgently needed. It has been reported that selective starvation of Plasmodium falciparum by blocking the function of hexose transporter 1 (PfHT1) protein, the only known transporter for glucose uptake in P. falciparum, could provide an alternative approach to fight the drug resistant malaria parasites. In this study, three high affinity molecules (BBB_25784317, BBB_26580136 and BBB_26580144) that have shown the best docked conformation and least binding energy with PfHT1 were shortlisted. The docking energy of BBB_25784317, BBB_26580136 and BBB_26580144 with PfHT1 were -12.5, -12.1 and -12.0 kcal/mol, respectively. In the follow up simulation studies, the protein 3D structure maintains considerable stability in the presence of the compounds. It was also observed that the compounds produced a number of hydrophilic and hydrophobic interactions with the protein allosteric site residues. This demonstrates strong intermolecular interaction guided by close distance hydrogen bonds of compounds with Ser45, Asn48, Thr49, Asn52, Ser317, Asn318, Ile330 and Ser334. Revalidation of compounds binding affinity was conducted by more appropriate simulation based binding free energy techniques (MM-GB/PBSA and WaterSwap). Additionally, entropy assay was performed that further strengthen the predictions. In silico pharmacokinetics confirmed that the compounds would be suitable candidates for oral delivery due to their high gastrointestinal absorption and less toxic reaction. Overall, the predicted compounds are promising and could be further sought as antimalarial leads and subjected to thorough experimental investigations.Communicated by Ramaswamy H. Sarma.

Field evaluation of the novel One Step Malaria Pf and Pf/Pv rapid diagnostic tests and the proportion of HRP-2 gene deletion identified on samples collected in the Pwani region, Tanzania

Background

Malaria rapid diagnostic tests (mRDTs) have played an important role in the early detection of clinical malaria in an endemic area. While several mRDTs are currently on the market, the availability of mRDTs with high sensitivity and specificity will merit the fight against malaria. We evaluated the field performance of a novel One Step Malaria (P.f/P.v) Tri-line and One Step Malaria (P.f) rapid test kits in Pwani, Tanzania.

Methods

In a cross-sectional study conducted in Bagamoyo and Kibiti districts in Tanzania, symptomatic patients were tested using the SD BIOLINE, One Step Malaria (P.f/P.v) Tri-line and One Step Malaria (P.f) rapid test kits, microscope, and quantitative Polymerase Chain Reaction (qPCR). An additional qPCR assay was carried out to detect Histidine-Rich Protein 2 (HRP-2) gene deletion on mRDT negative but microscope and qPCR positive samples. Microscope results confirmed by qPCR were used for analysis, where qPCR was used as a reference method.

Results

The sensitivity and specificity of One Step P.f/P.v Tri-line mRDTs were 96.0% (CI 93.5-97.7%) and 98.3% (CI 96.8-99.2%), respectively. One Step P.f mRDT had sensitivity and specificity of 95.2% (CI 92.5-97.1%) and 97.9% (CI 96.3-99.0%) respectively. Positive predictive value (PPV) was 97.6% (CI 95.4-98.7%) and negative predictive value (NPV) was 96.2% (CI 95.5-98.3%) for the One Step P.f/P.v Tri-line mRDTs respectively, while One Step P.f mRDT had positive predictive value (PPV) and negative predictive value (NPV) of 97.0% (CI 94.8-98.3%) and 96.7 (CI 94.9-97.9%) respectively. 9.8% (CI 7.84-11.76) of all samples tested and reported to be malaria-negative by mRDT had HRP-2 gene deletion.

Conclusion

One Step Malaria P.f/P.v Tri-line and One Step Malaria P.f rapid test kits have similar sensitivity and specificity as the standard mRDT that is currently in the market, demonstrating the potential to contribute in the fight against malaria in endemic settings. However, the identified malaria parasites population with HRP-2 gene deletion pose a threat to the current mRDT usability in the field and warrants further investigations.

Malaria among the elderly in five communities of Osun East district, Southwest Nigeria: Prevalence and association with non-communicable diseases

Objective:

The level of immunity against pathogens decreases with old age. As a result, the elderly may be regarded to be at increased risk of malaria morbidity and fatality. There is paucity of studies on malaria among the elderly population in Osun East district, Southwest Nigeria. This study aimed to determine the prevalence of malaria and its association with medical comorbidities among the elderly.

Methods:

A descriptive cross-sectional study was carried out, which involved 972 adult residents of five communities in Osun State, who were selected using a multistage random sampling technique. Data was collected with aid of a structured questionnaire. The medical history of respondents and anthropometric measures were obtained. The presence of malaria parasitaemia in the respondents was determined by rapid diagnostic test (RDT). Appropriate descriptive and inferential analyses were done.

Results:

Out of the 972 respondents, 504 (51.9%) were 60 years and above. The overall prevalence of malaria RDT positivity was 4%. The positivity rate was higher among the elderly (4.6%) compared to those less than 60 years (3.4%), albeit not statistically significant ( p = 0.36). Among these elderlies, 52.6% and 16.1% used insecticide-treated nets and insecticide sprays, respectively. There was no association between the prevalence of malaria positivity and comorbid conditions, such as hypertension ( p = 0.37), overweight/obesity ( p = 0.77), or diabetes ( p = 0.15). Malaria positivity rate was also not significantly associated with the use of insecticide-treated nets ( p = 0.64) or insecticide sprays ( p = 0.45).

Conclusion:

The malaria positivity rate was higher among the elderly in the study area, although not statistically significant. The prevalence was not associated with comorbid medical conditions.

Predictors of malaria vaccine uptake among children 6-24 months in the Kassena Nankana Municipality in the Upper East Region of Ghana

BACKGROUND

The Malaria Vaccine Implementation Programme (MVIP) coordinates the routine implementation of the RTS,S vaccine pilot in strategically selected locations in Malawi, Kenya, and Ghana. The pilot programme thoroughly assesses the programmatic feasibility of administering the four doses of the RTS,S vaccine. It will also assess the impact on malaria morbidity and mortality, as well as monitor and detect the vaccine's safety for routine usage. The malaria vaccine was introduced into Ghana's routine vaccination programme in May 2019 in seven regions, comprising 42 districts, including Kassena Nankana Municipal in the Upper East region of Ghana. Therefore, this study seeks to assess the predictors of the malaria vaccine uptake in children 6 to 24 months in the Kassena Nankana Municipal in Ghana.

METHODS

The survey used a cross-sectional study design and included 422 mothers/caregivers with children aged 6 to 24 months from the Kassena Nankana Municipality. WHO cluster survey questionnaire was altered for use in data gathering with caregivers as respondents. The Statistical Package for the Social Sciences (SPSS) version 25.0 (for descriptive statistics) and Stata version 13 (for calculating odds ratios) were used to analyse the data.

RESULTS

The findings depict that, the mean age of respondents for the study was 27 ± 5 years and average age of children was 15 ± 8 months. The study found that coverage uptake was high (94%). Chi-square and odds ratios testing revealed statistically significant associations between health service factors and vaccine uptake: education on malaria vaccine cOR(Cl); 9.69(3.496-25.425), (P < 0.001), giving caregivers the option to accept malaria vaccine cOR(Cl); 7.04 (2.759-17.476), (P < 0.001). Confidence in the efficiency of the vaccination was found to have a statistically significant association with malaria vaccine uptake (P < 0.005) and (p < 0.001) for 'somewhat confidence' and 'not confidence at all', respectively. Attitude of health workers was found to be significant predictor of malaria vaccine uptake (P < 0.003).

CONCLUSION

Malaria vaccine uptake was high among the study population in the municipality; however, dose four uptake coverage by age two was low. This indicates that mothers/caregivers did not understand the notion of immunization throughout the second year of life. As a result, it is recommended that the municipality raise awareness about immunization services among mothers/caregivers beyond year one in order to improve performance and reduce the risk of disease outbreaks in the municipality.

Implication of asymptomatic and clinical Plasmodium falciparum infections on biomarkers of iron status among school-aged children in Malawi

Background

Iron status is considered as a continuum from an iron deficiency with anaemia, without anaemia, varying amounts of stored iron to iron overload. The burden of Plasmodium falciparum infections is typically high among school-aged children (SAC). Nonetheless, SAC are often less likely to be covered by malaria interventions, making them a group with an untreated reservoir of parasite transmission. This study aimed to assess the effects of asymptomatic and clinical malaria infections on biochemical markers of iron status among SAC in Malawi.

Methods

Data from the 2015–2016 Malawi Micronutrient Survey (MNS) was used and multivariable logistic regression models using a generalized estimating equation to account for the complex cluster survey design were constructed. Blood samples of 684 children aged 5 to 14 years old were evaluated for clinical and asymptomatic malaria infections. Furthermore, blood samples were used to estimate haemoglobin (Hb), serum ferritin (SF) and, soluble transferrin receptors (sTfR) concentrations.

Results

Of the 684 SAC analysed, approximately 42% had asymptomatic malaria, while 41.0% had clinical malaria. Anaemia (low Hb levels), iron deficiency (low SF concentration), and functional iron deficiency (high sTfR levels) were found in 20%, 5%, and 30% of the children, respectively. School-aged children with asymptomatic malaria had increased odds of being anaemic (adjusted odds ratio [aOR]: 3.71, 95% confidence interval [CI]: 2.29–5.99) and increased levels of sTfR (aOR: 3.00, 95% CI 2.01–4.47). Similarly, SAC with clinical malaria had increased odds of being anaemic (aOR: 3.54, 95% CI 2.19–5.72) and increased levels of sTfR (aOR: 3.02, 95% CI 2.02–4.52).

Conclusions

Both asymptomatic and clinical malaria were independent risk factors for anaemia and functional iron deficiency (FID). The notion that asymptomatic and clinical malaria were associated with both anaemia and FID underscores the need for public health programmers to consider adding mass screening and treatment for malaria to existing school-based health programmes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04297-1.

Narrative Review of the Control and Prevention of Knowlesi Malaria

Despite the reduction in the number of cases of human malaria throughout the world, the incidence rate of knowlesi malaria is continuing to rise, especially in Southeast Asia. The conventional strategies for the prevention and control of human malaria can provide some protection against knowlesi malaria. Despite the numerous studies on the risk factors and the innovative methods that may be used to prevent and control the vectors of Plasmodium knowlesi, the incidence rate remains high. An integrated approach that includes environmental intervention should be adopted in order to ensure the successful control of zoonotic malaria. A combination of personal-level protection, vector control and environmental control may mitigate the risk of Plasmodium knowlesi transmission from macaques to humans and, ultimately, reduce the incidence rate of knowlesi malaria.

Risk score prediction model based on single nucleotide polymorphism for predicting malaria: a machine learning approach

BACKGROUND

The malaria risk prediction is currently limited to using advanced statistical methods, such as time series and cluster analysis on epidemiological data. Nevertheless, machine learning models have been explored to study the complexity of malaria through blood smear images and environmental data. However, to the best of our knowledge, no study analyses the contribution of Single Nucleotide Polymorphisms (SNPs) to malaria using a machine learning model. More specifically, this study aims to quantify an individual's susceptibility to the development of malaria by using risk scores obtained from the cumulative effects of SNPs, known as weighted genetic risk scores (wGRS).

RESULTS

We proposed an SNP-based feature extraction algorithm that incorporates the susceptibility information of an individual to malaria to generate the feature set. However, it can become computationally expensive for a machine learning model to learn from many SNPs. Therefore, we reduced the feature set by employing the Logistic Regression and Recursive Feature Elimination (LR-RFE) method to select SNPs that improve the efficacy of our model. Next, we calculated the wGRS of the selected feature set, which is used as the model's target variables. Moreover, to compare the performance of the wGRS-only model, we calculated and evaluated the combination of wGRS with genotype frequency (wGRS + GF). Finally, Light Gradient Boosting Machine (LightGBM), eXtreme Gradient Boosting (XGBoost), and Ridge regression algorithms are utilized to establish the machine learning models for malaria risk prediction.

CONCLUSIONS

Our proposed approach identified SNP rs334 as the most contributing feature with an importance score of 6.224 compared to the baseline, with an importance score of 1.1314. This is an important result as prior studies have proven that rs334 is a major genetic risk factor for malaria. The analysis and comparison of the three machine learning models demonstrated that LightGBM achieves the highest model performance with a Mean Absolute Error (MAE) score of 0.0373. Furthermore, based on wGRS + GF, all models performed significantly better than wGRS alone, in which LightGBM obtained the best performance (0.0033 MAE score).

Temperature impacts the environmental suitability for malaria transmission by Anopheles gambiae and Anopheles stephensi

Extrinsic environmental factors influence the spatiotemporal dynamics of many organisms, including insects that transmit the pathogens responsible for vector-borne diseases (VBDs). Temperature is an especially important constraint on the fitness of a wide variety of ectothermic insects. A mechanistic understanding of how temperature impacts traits of ectotherms, and thus the distribution of ectotherms and vector-borne infections, is key to predicting the consequences of climate change on transmission of VBDs like malaria. However, the response of transmission to temperature and other drivers is complex, as thermal traits of ectotherms are typically nonlinear, and they interact to determine transmission constraints. In this study, we assess and compare the effect of temperature on the transmission of two malaria parasites, Plasmodium falciparum and Plasmodium vivax, by two malaria vector species, Anopheles gambiae and Anopheles stephensi. We model the nonlinear responses of temperature dependent mosquito and parasite traits (mosquito development rate, bite rate, fecundity, proportion of eggs surviving to adulthood, vector competence, mortality rate, and parasite development rate) and incorporate these traits into a suitability metric based on a model for the basic reproductive number across temperatures. Our model predicts that the optimum temperature for transmission suitability is similar for the four mosquito-parasite combinations assessed in this study, but may differ at the thermal limits. More specifically, we found significant differences in the upper thermal limit between parasites spread by the same mosquito (A. stephensi) and between mosquitoes carrying P. falciparum. In contrast, at the lower thermal limit the significant differences were primarily between the mosquito species that both carried the same pathogen (e.g., A. stephensi and A. gambiae both with P. falciparum). Using prevalence data, we show that the transmission suitability metric S T $$ S(T) $$ calculated from our mechanistic model is consistent with observed P. falciparum prevalence in Africa and Asia but is equivocal for P. vivax prevalence in Asia, and inconsistent with P. vivax prevalence in Africa. We mapped risk to illustrate the number of months various areas in Africa and Asia predicted to be suitable for malaria transmission based on this suitability metric. This mapping provides spatially explicit predictions for suitability and transmission risk.

Community-based house improvement for malaria control in southern Malawi: Stakeholder perceptions, experiences, and acceptability

House improvement (HI) refers to the full screening or closing of openings such as windows, doors, and eaves, as well as the installation of ceilings, to reduce mosquito-human contact indoors. HI is a viable supplementary intervention that reduces malaria transmission further than the existing strategies alone. In Malawi, HI has not been widely implemented and evaluated for malaria control. Concerns about lack of local evidence, durability in different epidemiological and cultural settings, and the cost of large-scale implementation are among the reasons the strategy is not utilised in many low-income countries. This study assessed community perceptions, experiences, and acceptability of community-led HI in Chikwawa district, southern Malawi. This was a qualitative study where separate focus group discussions were conducted with members from the general community (n = 3); health animators (n = 3); and HI committee members (n = 3). In-depth interviews were conducted with community members (n = 20), and key-informant interviews were conducted with health surveillance assistants and chiefs (n = 23). All interviews were transcribed and coded before performing a thematic content analysis to identify the main themes. Coded data were analysed using Nvivo 12 Plus software. Study participants had a thorough understanding of HI. Participants expressed satisfaction with HI, and they reported enabling factors to HI acceptability, such as the reduction in malaria cases in their villages and the safety and effectiveness of HI use. Participants also reported barriers to effective HI implementation, such as the unavailability and inaccessibility of some HI materials, as well as excessive heat and darkness in HI houses compared to non-HI houses. Participants indicated that they were willing to sustain the intervention but expressed the need for strategies to address barriers to ensure the effectiveness of HI. Our results showed the high knowledge and acceptability of HI by participants in the study area. Intensive and continued health education and community engagement on the significance of HI could help overcome the barriers and improve the acceptability and sustainability of the intervention.

Exposure of Anopheles gambiae larvae to a sub-lethal dose of an agrochemical mixture induces tolerance to adulticides used in vector control management

The heavy use of pesticides in agricultural areas often leads to the contamination of nearby mosquito larvae breeding sites. Exposure to complex mixtures of agrochemicals can affect the insecticide sensitivity of mosquito larvae. Our study objective was to determine whether agrochemical residues in Anopheline larval breeding sites can affect the tolerance of adults to commonly used adulticides. We focussed on Fludora® Fusion, a vector control insecticide formulation combining two insecticides (deltamethrin and clothianidin) with different modes of action. An. gambiae larvae were exposed to a sub-lethal dose of a mixture of agrochemical pesticides used in a highly active agricultural area on the Ivory Coast. Comparative bioassays with Fludora Fusion mixture and its two insecticide components (deltamethrin and clothianidin) were carried out between adult mosquitoes exposed or not to the agrochemicals at the larval stage. A transcriptomic analysis using RNA sequencing was then performed on larvae and adults to study the molecular mechanisms underlying the phenotypic changes observed. Bioassays revealed a significantly increased tolerance of adult females to clothianidin (2.5-fold) and Fludora Fusion mixture (2.2-fold) following larval exposure to agrochemicals. Significantly increased tolerance to deltamethrin was not observed suggesting that insecticide exposure affects the adult efficacy of the Fludora Fusion mixture mainly through mechanisms acting on clothianidin. Transcriptomic analysis revealed the potential of agrochemicals to induce various resistance mechanisms including cuticle proteins, detoxification action and altered insecticide sequestration. These results suggest that although the Fludora Fusion mixture is effective for adult vector control, its efficacy may be locally affected by the ecological context. The present study also suggests that, although the complex interactions between the use of agrochemicals and vector control insecticides are difficult to decipher in the field, they still must be considered in the context of insecticide resistance management programmes.

A Cross-Sectional Survey on the Malaria Control and Prevention Knowledge, Attitudes, and Practices of Caregivers of Children Under-5 in the Western Area of Sierra Leone

(1) Background: Children under 5 years of age are the most vulnerable to malaria infection, and they suffer serious complications. Sierra Leone is one of the countries with the highest malaria burden in the world. This study aimed to assess the knowledge, attitudes, and practices (KAPs) toward malaria control and prevention among caregivers of children under 5 in the Western Area of Sierra Leone. (2) Methods: A cross-sectional survey was conducted among caregivers of children under-5 visiting the out-patient department of six selected hospitals/community health centers. Data were collected via questionnaire interviews with 350 caregivers. (3) Results: A total of 97.1% of the respondents were women and the majority of them were young mothers; 46.3% of respondents were unemployed; and 27.1% received no education. Only 1.4% accessed malaria related information from the internet/social media. This KAPs survey indicated that a misconception of the cause, transmission, and clinical symptoms of malaria; unawareness of its lethality and its severity; and inappropriate prevention and treatment behaviors, such as self-medicating, were still in existence among some caregivers. However, a positive correlation in knowledge−attitudes (rs = 0.13, p < 0.05) and in attitudes−practices (rs = 0.45, p < 0.001) was revealed. The caregivers, being mothers and having at least a secondary education, demonstrated positive attitudes and practices. Meanwhile, more urban caregivers (79.8%) followed a complete malaria treatment course of artemisinin-based combination therapies than the rural (63.3%), but in view of insecticide treated net use, more rural caregivers presented positive attitudes (85.3%) and practices (70.1%) than the urban (69.9%, 52.0%). (4) Conclusions: For better protection of children under-5 against lethal malaria, it is essential to provide better guidance at the community level for their caregivers, especially young mothers, in order to reduce some misconceptions and inappropriate behaviors. An increase in education and employment opportunities for women, establishment of an accessible community-based malaria counselling service, and construction of an effective communication channel are also needed.

Intensity of insecticide resistance in the major malaria vector Anopheles funestus from Chikwawa, rural Southern Malawi

BACKGROUND

Malaria vector control using insecticide-based approaches has proven to be an effective strategy. However, widespread insecticide resistance among malaria vector populations across sub-Saharan Africa threatens to derail control efforts. This study was conducted in Chikwawa district, an area in rural southern Malawi characterised by persistent malaria transmission and reports of insecticide resistance in the local mosquito population. The aim of the was to characterise the intensity of insecticide resistance within a population of Anopheles funestus sensu lato (s.l.), a major vector of malaria in this district.

METHODS

Live adult females belonging to the An. funestus group were collected from households by indoor aspiration. The CDC bottle assay was used for phenotypic quantification of resistance to deltamethrin, permethrin and alpha-cypermethrin at 1×, 2.5×, 5× and 10× the recommended diagnostic dose for each of these insecticides. WHO tube assays were used to determine susceptibility to bendiocarb, dichlorodiphenyltrichloroethane (DDT) and pirimiphos-methyl insecticides at diagnostic concentrations.

RESULTS

Anopheles funestus s.l. exposed to 10× the recommended diagnostic dose was highly resistant to alpha-cypermethrin (mortality 95.4%); in contrast, mortality was 100% when exposed to both deltamethrin and permethrin at the same dose. Despite showing susceptibility to deltamethrin and permethrin at the 10× concentration, mortality at the 5× concentration was 96.7% and 97.1%, respectively, indicating moderate resistance to these two insecticides. WHO susceptibility assays indicated strong resistance against bendiocarb (mortality 33.8%, n = 93), whereas there was full susceptibility to DDT (mortality 98.9%, n = 103) and pirimiphos-methyl (mortality 100%, n = 103).

CONCLUSIONS

Strategies for managing resistance to insecticides, particularly against pyrethroids, must be urgently implemented to maintain the effectiveness of insecticide-based vector control interventions in the area. Such strategies include the wide-scale introduction of third-generation synergist insecticide-treated bed nets (ITNs) and next-generation dual active ingredient ITNs. The use of effective non-pyrethroids, such as pirimiphos-methyl, clothianidin and potentially DDT, could provide a window of opportunity for indoor residual spraying across the district. This strategy would support the current Malawi Insecticide Resistance Management Plan which aims at rotating insecticides to minimise selection pressure and slow down the evolution of resistance to approved insecticides. These actions will help to prevent malaria vector control failure and improve progress towards malaria elimination.

Systematic Review on Diversity and Distribution of Anopheles Species in Gabon: A Fresh Look at the Potential Malaria Vectors and Perspectives

Gabon is located in the malaria hyper-endemic zone, where data concerning malaria vector distribution remains fragmentary, making it difficult to implement an effective vector control strategy. Thus, it becomes crucial and urgent to undertake entomological surveys that will allow a better mapping of the Anopheles species present in Gabon. In this review, we examined different articles dealing with Anopheles in Gabon from ProQuest, Web of Science, PubMed, and Google scholar databases. After applying the eligibility criteria to 7543 articles collected from four databases, 42 studies were included that covered a 91-year period of study. The review revealed a wide diversity of Anopheles species in Gabon with a heterogeneous distribution. Indeed, our review revealed the presence of 41 Anopheles species, of which the most abundant were members of the Gambiae and Nili complexes and those of the Funestus and Moucheti groups. However, our review also revealed that the major and minor vectors of malaria in Gabon are present in both sylvatic, rural, and urban environments. The observation of human malaria vectors in sylvatic environments raises the question of the role that the sylvatic environment may play in maintaining malaria transmission in rural and urban areas. Ultimately, it appears that knowledge of biodiversity and spatial distribution of Anopheles mosquitoes is fragmentary in Gabon, suggesting that additional studies are necessary to complete and update these entomological data, which are useful for the implementation of vector control strategies.