Malaria Control Programme Research Articles

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.

The non-inferiority of piperonyl-butoxide Yorkool® G3 insecticide-treated nets compared to Olyset®Plus measured by Anopheles arabiensis mortality in experimental huts in Tanzania

BackgroundNon-inferiority trials are recommended by the World Health Organization (WHO) to demonstrate that health products show comparable efficacy to that of existing standard of care. As part of the WHO Global Malaria Programme (GMP) process of assessment of malaria vector control products, a second-in-class insecticide-treated net (ITN) must be shown to be non-inferior to a first-in-class product based on mosquito mortality. The public health impact of the first-in-class pyrethroid-piperonyl butoxide (PBO) ITN, Olyset® Plus, has been demonstrated in epidemiological trials in areas with insecticide-resistant mosquitoes, but there is a need to determine the efficacy of other pyrethroid-PBO nets to ensure timely market availability of nets in order to increase access to ITNs. The non-inferiority of a deltamethrin-PBO ITN Yorkool® G3 was evaluated entomologically against Olyset® Plus in experimental huts in Tanzania, following WHO guidelines for non-inferiority trials.MethodsThe trial of the two pyrethroid-PBO ITNs was conducted in experimental huts in Lupiro, Tanzania, using a randomized 7 × 7 Latin square block design. The study ran for 49 nights in 14 huts assessing the mosquito mortality and blood-feeding of wild, free-flying, pyrethroid-resistant Anopheles arabiensis. Using the non-inferiority approach, the comparative efficacy (primary endpoint was mosquito mortality at 24 h and secondary endpoint was blood-feeding) of unwashed and 20 times field-washed pyrethroid-PBO Yorkool® G3 ITNs, were compared with the first-in-class product Olyset® Plus and against a pyrethroid-only ITN, PermaNet® 2.0 ITNs, as a standard comparator.ResultsThe experimental hut trial demonstrated non-inferiority and superiority of Yorkool® G3 to Olyset® Plus based on mosquito mortality [51% vs. 39%, OR 1.68 (95% CI 1.50–1.88)], given that lower 95% CI exceeded 0.74 (delta of 39%) and the margin of no difference (1). Blood-feeding inhibition was high for all treated ITNs (> 90%) and Yorkool® G3 was non-inferior to Olyset® Plus [4% vs. 2%, OR 1.81 (95% CI 1.46–2.39)], given that upper 95% CI was less than 4.85 (delta of 4%). The pyrethroid-PBO ITNs were superior to the pyrethroid-only net, PermaNet® 2.0, as determined by both the proportion of mortality and blood-feeding of mosquitoes (p-value < 0.05).ConclusionYorkool® G3 ITNs demonstrated non-inferiority to the first-in-class Olyset® Plus and superiority over the standard pyrethroid-only ITN, PermaNet® 2.0 as measured by mortality and blood-feeding inhibition of wild pyrethroid-resistant An. arabiensis mosquitoes. Yorkool® G3 ITNs are potential tools for the control of metabolic insecticide-resistant malaria vectors, and their market availability will contribute to the cost-effective selection of ITNs by malaria control programmes to improve population access to ITNs.

Distribution of Plasmodium falciparum Chloroquine Resistance Transporter (Pfcrt) and Plasmodium falciparum Multidrug Resistance 1(Pfmdr-1) Genes in Ilorin North-central Nigeria

Malaria remains a major health problem globally, especially in Sub-Saharan Africa. The ease of developing resistance to anti-malaria drugs by Plasmodium falciparum is a serious challenge to malaria control and elimination programs. Consequently, continuous monitoring of drug efficacy is necessary to ascertain effective treatment policies. The study investigated the distribution pattern of these genes in Plasmodium falciparum isolates in Ilorin metropolis. One hundred and three samples were collected randomly from 5 hospitals in Ilorin metropolis. The samples were amplified at codon 76 and 86 for Pfcrt and Pfmdr-1 respectively using PCR/Restricted Fragment Length Polymorphism (RFLP). Drug susceptible alleles were most prevalent in the study area (K76 and N86) with 31% and 40% respectively, followed by drug resistance alleles (86Y) with 13%, and the least prevalent (2%) was the mixed alleles K76T. UITH has the highest number of susceptible alleles followed by CSC 38% and 46% for K76 and N86 respectively. There are significant differences in the distribution of these alleles and the study sites (P55&lt; 0.05). The prevalence of resistance alleles in the area is a welcome development that can be employed for the possible re-introduction of CQ to treat malaria in the study area. It will be an advantage over expensive ACT because it is safe, cheap, and readily affordable.

Assessment of household preferences for net textile type (polyester versus polyethylene) for decision-making of the National Malaria Control Programme in Burkina Faso: methods for a quasi-experimental study

BackgroundA quasi-experimental comparative trial will be designed in Burkina Faso. The study will compare the use and preferences for two groups types of insecticide-treated nets textile: polyester-based and polyethylene-based, according to their use and preferences in selected health districts. These health districts will be selected in three eco-climate zones (Sahelian, dry savannah and wet savannah) in the country. These findings will inform decisions on future net procurements for national malaria control programme in 2025.MethodsQuantitative surveys and qualitative data collection will be carried out to gather information on the type of net textile most commonly used and preferred by the community. They will be performed between the end of the dry season and the early rainy season. The quantitative surveys involved household interviews with households and individuals’ questionnaires, while the qualitative data collection involved in-depth individual interviews and focus group discussions to explore and clarify some key evaluation criteria. A total of 9450 insecticide-treated nets were surveyed for quantitative survey purposes. For the qualitative study, 48 in-depth individual interviews and 12 focus group discussions were carried out. A mixed model approach combining the results from quantitative surveys and qualitative studies will be used for decision-making on the type of insecticide-treated net preference.ConclusionThis methodological approach will be used by the National Malaria Control Programme to conduct this study on determinants of net use in Burkina Faso in order to provide robust evidence across diverse settings. This mixed-methods approach for data collection and analysis could be used in other countries to provide evidence that would help to increase the uptake of insecticide-treated nets, the main vector control tool in Africa.

A Comprehensive Review of Malaria Control Strategies in Africa: Historical Perspectives, Policy Frameworks, Innovations, and Future Directions

Malaria remains a significant public health challenge in Africa, affecting children under five and pregnant women. Historically, malaria has impacted Africa from ancient Egyptian times to the colonial era, with early control efforts often thwarted by limited resources and political instability. Today, Africa accounts for approximately 94% of global malaria cases and deaths, primarily affecting children under five and pregnant women. Despite progress in some regions, challenges such as financial constraints, inadequate healthcare infrastructure, and the need for robust community engagement persist. This review evaluates the role of African governments and regional bodies in malaria control, emphasizing the importance of comprehensive policy frameworks, effective governance, and well-structured National Malaria Control Programs. Innovative strategies and technologies, such as malaria vaccines, genetically modified mosquitoes, and digital tools, offer new avenues for malaria control. However, challenges in implementation, funding, and acceptance need addressing. Strengthening healthcare infrastructure, capacity building, community health workers, and public awareness campaigns are crucial for malaria control. Ongoing research and development are essential for advancing malaria control efforts, and indigenous knowledge and local innovations should complement modern approaches for culturally sensitive interventions. In conclusion, achieving a malaria-free Africa demands a multifaceted approach involving historical insights, innovative strategies, strengthened healthcare systems, community engagement, sustainable funding, and continuous research. The collective efforts of governments, international partners, researchers, and communities are pivotal in overcoming malaria and securing a healthier future for millions across the continent. Keywords: Malaria, Africa: Historical Perspectives, Policy Frameworks, Innovations, Future Directions

Resistance to Antimalarial Drugs in Uganda: Current Status and Future Directions

Antimalarial drug resistance posed a significant challenge to malaria control in Uganda, where Plasmodium falciparum remains the predominant strain. This review examined the current status of antimalarial drug resistance in Uganda, focusing on the mechanisms underlying resistance, epidemiological trends, and the impact on malaria control programs. Chloroquine and sulfadoxine-pyrimethamine resistance have been well-documented, and recent concerns about reduced efficacy of artemisinin-based combination therapies (ACTs) highlight ongoing challenges. The review identified key mechanisms of resistance, including genetic mutations, drug efflux, metabolic pathway alterations, and potential biofilm formation. The implications of resistance on treatment efficacy, healthcare costs, and policy adjustments are discussed. Future directions included strengthening surveillance systems, optimizing combination therapies, investing in research and development, implementing integrated vector management strategies, and enhancing public education and community engagement. Related published literatures were reviewed and analysis of recent data on drug resistance patterns in Uganda was carried out and utilised in compiling this paper. By exploring these dimensions, the review aims to provide actionable insights for policymakers, healthcare providers, and researchers to effectively address drug resistance and advance malaria control efforts in Uganda. Keywords: Antimalarial Drug Resistance, Plasmodium falciparum, Chloroquine Resistance, Artemisinin-Based Combination Therapies (ACTs), Surveillance and Monitoring.

Community participatory mapping of malaria mosquito breeding sites in Mozambique

BackgroundThe community involvement and the people’s knowledge allow detailed information about the distribution, location, and identification of mosquito breeding-sites. Information which is fundamental for their efficient management and elimination. Since participatory mapping has proven to be an effective tool to identify health determinants, the study aimed to apply the methodology to identify and map potential mosquito breeding-sites in Tambai, Nhamatanda, Mozambique.MethodsA study was conducted using an open-question guide. Discussions were held with 94 participants within ten focus groups, selected in collaboration with local community leaders. A thematic content analysis was performed. Descriptive statistics were used to characterize sociodemographic data. Geographic Positioning System (GPS) was used to compare and map potential breeding-sites. Children under 5 years of age who tested positive for malaria, were georeferenced to the maps.ResultsParticipants were aware of causes and transmission of malaria, no major differences between groups were observed regarding knowledge and identification of principal potential breeding sites. Gender and age determined specific information, number, and diversity of identified potential breeding sites. A total of 125 potential breeding-sites (36 permanent and 89 temporary) were mapped.ConclusionsSeveral potential mosquito breeding-sites were identified, located throughout the community, often near house conglomerates and malaria cases. Community participatory mapping could be used to identify potential mosquito breeding-sites by the national malaria control programmes to establish an efficient larval surveillance system, while improving community engagement and control strategies.Trial registration: ClinicalTrials.gov ID: NCT04419766.

Long-lasting insecticidal nets use and the prevalence of Plasmodium falciparum infection among pregnant women attending antenatal care at the Bonassama District Hospital, Littoral Region of Cameroon: a cross-sectional study

BackgroundMalaria during pregnancy continues to be a significant cause of morbidity and mortality for both infants and mothers, particularly in sub-Saharan African (SSA) countries, despite increased efforts to control it. The utilization of long-lasting insecticide-treated nets (LLINs) during pregnancy is a well-established strategy to reduce the prevalence of malaria. Nonetheless, inadequate adherence remains a persistent challenge in certain regions with high malaria endemicity. This research aimed to assess the effectiveness of long-lasting insecticidal nets in preventing asymptomatic malaria infections among pregnant women attending antenatal care at the Bonassama District Hospital in the Littoral Region of Cameroon.MethodsA hospital-based cross-sectional study was conducted from March to June 2022. Data on sociodemographic characteristics and LLIN usage were collected through a structured questionnaire, while asymptomatic malaria infections were identified using a PfHRP2/pLDH malaria qualitative rapid diagnostic kit. The relationship between categorical variables was analyzed using the chi-square test and logistic regression at a significance level of 5%.ResultsOut of the 411 pregnant women included in the study, 35.4% were diagnosed with malaria. The LLIN utilization rate was 65.1%. The risk of malaria infection was 2.7 times higher (AOR = 2.75, 95% CI = 1.83–4.14, p < 0.001) among women who did not consistently use LLINs compared to those who did. Pregnant women in their first trimester (AOR = 3.40, 95% CI = 1.24–4.64, p = 0.010) and second trimester (AOR = 1.90, 95%CI = 0.99–3.62, p = 0.055) were more likely to sleep under net when compared to those in the third trimester. Younger women 20–29 years (71.4%), those in the first trimester (69.6%) and those who had the nets before pregnancy (68.9%) were amongst those who frequently used use the nets. Among the reasons reported for not frequently using LLINs were heat (55.2%), suffocation (13.6%) and the smell of nets (8.4%).ConclusionThe use of LLIN was moderately high among the participants in this study, though still below national target. Age group, religion and gestation period were the major factors determining the use of LLINs. Considering the proven effectiveness of LLINs in reducing malaria morbidity and mortality, it is imperative for the National Malaria Control Programme (NMCP) to remain focused in promoting both LLIN ownership and utilization to achieve the national target of 100% and 80%, respectively.

Circulation of Non-falciparum Species in Niger: Implications for Malaria Diagnosis.

Niger's National Malaria Control Programme and its partners use histidine-rich protein 2-based RDTs, which are specific to Plasmodium falciparum diagnosis. This study aimed to screen for the circulation of non-falciparum species in Zinder, a region of Niger, West Africa. A cross-sectional study was carried out from July to December 2022 at the district hospital of the Zinder region of Niger. P falciparum histidine-rich protein 2-based rapid diagnostic tests were performed, and dried blood spot samples were collected for further laboratory multiplexed photo-induced electron transfer-polymerase chain reaction (PET-PCR) analysis on positive light microscopy from all patients with fever who attended the Zinder district hospital during the study period. In total, 340 dried blood spots were collected and analyzed by PET-PCR. Overall, 73.2% (95% CI, 68.2%-77.9%; 249/340) were positive for Plasmodium genus and species and represented the study population. Plasmodium species proportions were 89.5% (95% CI, 85.1%-93.1%; 223/249) for P falciparum, 38.5% (95% CI, 32.5%-44.9%; 96/249) for P malariae, 10.8% (95% CI, 7.3%-15.4%; 27/249) for P vivax, and 1.6% (95% CI, .4%-4.1%; 4/249) for P ovale. Single infection with Plasmodium species counted for 61.8% (95% CI, 55.5%-67.9%; 154/249), and the mixed infections rate, with at least 2 Plasmodium species, was 38.1% (95% CI, 32.1%-44.5%; 95/249). Single non-falciparum infections represented a rate of 10.0% (95% CI, 6.6%-14.5%; 25/249). This study confirms the first evidence of Plasmodium vivax by PET-PCR in Niger in addition to the other 3 Plasmodium species. These findings underline the need to adapt malaria diagnostic tools and therapeutic management, as well as the training of microscopists, for recognition of non-falciparum plasmodial species circulating in the country. This will better inform the strategies toward malaria control and elimination, as well as the decision making of the health authorities of Niger.

Stakeholder Insights on Malaria Elimination Strategies in Pangandaran, West Java: a Qualitative Analysis

Indonesia has launched a determined effort to eliminate malaria by 2023, focusing on Java and Bali. Despite these efforts, Pangandaran in Java still faces malaria cases. This study aims to meticulously delve into the intricacies of the malaria elimination program's implementation while conducting a comprehensive evaluation of its effectiveness. Structured interviews were conducted with key stakeholders responsible for the malaria program in Pangandaran to extract invaluable insights. The study, carried out in November 2022, followed qualitative research with narrative analysis to reveal nuanced narratives from the participants. Findings from this rigorous analysis revealed a harmonious alignment between the malaria control program in Pangandaran and the Indonesian Ministry of Health guidelines. The strategy to combat malaria vectors in Pangandaran included mosquito net distribution, strategic larvicide application, and educational campaigns like Malaria Awareness Society (MASAMA). The expectation is that the current effective control program will resonate within the Pangandaran community, ultimately leading to the realization of the 2023 elimination target.

Practical Application of a Relationship-Based Model to Engagement for Gene-Drive Vector Control Programs.

Engagement is an important component in the advancement of gene-drive vector control research programs as developers look to transition the technology from the laboratory to the field. As research advances and engagement surrounding this novel technology is put into practice, knowledge can be gained from practical experiences and applications in the field. A relationship-based model (RBM) provides a framework for end-user development of engagement programs and strategies. The model places end users at the center of the engagement decision-making processes rather than as recipients of predetermined strategies, methods, and definitions. Successful RBM application for healthcare delivery has previously been demonstrated, and the University of California Malaria Initiative (UCMI) has applied this model to its gene-drive program in the Democratic Republic of São Tomé and Príncipe. The model emphasizes the importance of local leadership in the planning, development, and implementation of all phases of project engagement. The primary aim of this paper is to translate the model from paper to practice and provide a transparent description, using practical examples, of the UCMI program implementation of RBM at its field site. End-user development of the UCMI engagement program provides a unique approach to the development of ethical, transparent, and effective engagement strategies for malaria control programs. This paper may also serve as a reference and example for projects looking to establish an engagement program model that integrates end-user groups in the decision-making processes surrounding engagement.

For Malaria Elimination, India Needs to Integrate Its Research and Control Arms.

India has targeted malaria elimination by 2030. The national malaria control program has positioned its strategies in this direction. Substantial support in the form of dynamic research inputs leading to policy formulation and change is needed to steer the country towards malaria elimination. Indian Council of Medical Research (ICMR), India's nodal research body, has been generating evidence and helping to frame several policies ranging from malaria management to vector control operations. Since the country is preparing for malaria elimination, the connection between the programmatic needs and the research agenda needs further strengthening. Typically, the national malaria control program handles the implementation of programmatic activities, while the national research body, ICMR, conducts research studies to generate evidence. We propose a virtual integration of the activities conducted by these two entities to maximize the potential for translating research findings into programmatic policies. Joint monitoring of drug and insecticide resistance, codevelopment and utilization of more innovative surveillance systems, data-backed mitigation responses, and overcoming last-mile challenges are reasons for the virtual amalgamation of the two bodies. Timely translation of research outputs into policy, co-opting of workforce and material resources, joint capacity building, and synergistic advocacy are benefits of the proposed new alliance for more efficient operations. The close functioning will provide impetus to narrow down current gaps and disrupt traditional barriers, galvanizing the country toward malaria elimination.

Proactive home-based malaria management in rural communities of Bassar Health District in northern Togo from 2014 to 2017: PECADOM + , a pilot experiment

BackgroundTogo's National Malaria Control Programme has initiated an active home-based malaria management model for all age groups in rural areas of Bassar Health District. This report describes the model, reports its main results, and determines the factors associated with positive rapid diagnostic test results.MethodsFrom 2014 to 2017, in three peripheral care units of Bassar Health District (Binaparba, Nangbani, and Baghan), community health workers visited residents' homes weekly to identify patients with malaria symptoms, perform rapid diagnostic tests in symptomatic patients, and give medication to positive cases. Univariate and multivariate logistic regression models were used to determine the factors associated with positive tests.ResultsThe study covered 11,337 people (817 in 2014, 1804 in 2015, 2638 in 2016, and 6078 in 2017). The overall mean age was 18 years (95% CI 5–29; min–max: 0–112 years). The median age was 10 years (SD: 16.9). The proportions of people tested positive were 75.3% in Binaparba, 77.4% in Nangbani, and 56.6% in Baghan. The 5–10 age group was the most affected category (24.2% positive tests). Positive tests were more frequent during the rainy than during the dry season (62 vs. 38%) and the probability of positive test was 1.76 times higher during the rainy than during the dry season (adjusted OR = 1.74; 95% CI 1.60–1.90). A fever (37.5 °C or higher) increased significantly the probability of positive test (adjusted OR = 2.19; 95% CI 1.89–2.54). The risk of positive test was 1.89 times higher in passive than in active malaria detection (adjusted OR = 1.89; 95% CI 1.73–2.0).ConclusionsThis novel experimental community and home-based malaria management in Togo suggested that active detection of malaria cases is feasible within 24 h, which allows rapid treatments before progression to often-fatal complications. This PECADOM + program will help Togo's National Malaria Control Programme reduce malaria morbidity and mortality in remote and hard-to-reach communities.

Community perspective and healthcare assessment in malaria endemic states of India: a cross-sectional study protocol

IntroductionIndia’s contribution to the malaria burden was highest in South-East Asia Region in 2021, accounting for 79% of the estimated malaria cases and 83% of malaria-related deaths. Intensified Malaria Control...

Parallel Evolution in Mosquito Vectors-A Duplicated Esterase Locus is Associated With Resistance to Pirimiphos-methyl in Anopheles gambiae.

The primary control methods for the African malaria mosquito, Anopheles gambiae, are based on insecticidal interventions. Emerging resistance to these compounds is therefore of major concern to malaria control programs. The organophosphate (OP), pirimiphos-methyl, is a relatively new chemical in the vector control armory but is now widely used in indoor-residual spray campaigns. While generally effective, phenotypic resistance has developed in some areas in malaria vectors. Here, we used a population genomic approach to identify novel mechanisms of resistance to pirimiphos-methyl in A. gambiae s.l mosquitoes. In multiple populations, we found large and repeated signals of selection at a locus containing a cluster of detoxification enzymes, some of whose orthologs are known to confer resistance to OPs in Culex pipiens. Close examination revealed a pair of alpha-esterases, Coeae1f and Coeae2f, and a complex and diverse pattern of haplotypes under selection in A. gambiae, A. coluzzii and A. arabiensis. As in C. pipiens, copy number variants have arisen at this locus. We used diplotype clustering to examine whether these signals arise from parallel evolution or adaptive introgression. Using whole-genome sequenced phenotyped samples, we found that in West Africa, a copy number variant in A. gambiae is associated with resistance to pirimiphos-methyl. Overall, we demonstrate a striking example of contemporary parallel evolution which has important implications for malaria control programs.

Supporting health systems and environment in the Democratic Republic of Congo: A call for action.

Developing nations have to overcome a number of obstacles to fulfill the Sustainable Development Goals. The Democratic Republic of Congo is one of the five poorest nations in the world and faces several challenges in combating problems related to poverty, health, and sanitation while linking the environment to anthropogenic activities. This study analyzes anthropogenic activities and their impact on the environment while providing access to the public health of the Congolese population based on the objectives of sustainable development. Thirty-five articles were selected for further analysis as well as relative data. In 2022, 21 million cases of malaria were recorded by the national malaria control program, with 13,000 cases of death. The Democratic Republic of Congo has the highest typhoid incidence, with 315 cases per 100,000 people. A number of 31,342 cases of cholera were reported in 2023, according to multiple reports, with 230 deaths, mainly affecting children. In the same year, a triple epidemic of typhoid, shigellosis, and cholera was identified, with 2389 cases and 52 deaths. These observations cause a health emergency, which can be alleviated and resolved by the establishment of an adequate sanitation system. Waste can be recycled and returned to usable raw materials. Finally, it will be necessary to establish a water safety management plan to combat all diseases linked to the consumption of nonpotable water and improve national coverage on the treatment of recent cases to reduce and at best avoid observed cases of death.

Small dams drive Anopheles abundance during the dry season in a high malaria burden area of Malawi.

This study explores the influence of small dams on the exposure to malaria vectors during the dry season in Kasungu district, Malawi, an area recently identified as high priority for malaria interventions by the National Malaria Control Programme. Small dam impoundments provide communities with a continuous supply of water for domestic and agricultural activities across sub-Saharan Africa and are considered vital to food security and climate change resilience. However, these permanent water bodies also create ideal breeding sites for mosquitoes in typically arid landscapes. The study focuses on a specific dam impoundment and its vicinity, aiming to assess its spatial and temporal influence on indoor vector densities. From May to August 2021, CDC light traps were used to measure indoor mosquito densities for two consecutive nights per month in three communities located at increasing distances from the dam (0, ~1 and ~2 km). Simultaneously, drone imagery was captured for each community, enabling the identification of additional standing water within approximately 400 m of selected households. Larval sampling was carried out within the impoundment periphery and in additional water bodies identified in the drone imagery. Generalised linear mixed models (GLMMs) were employed to analyse the indoor Anopheles abundance data, estimating the effects of household structure (open/closed eaves), month, temperature and water proximity on malaria vector exposure. Throughout 685 trapping nights, a total of 1256 mosquitoes were captured, with 33% (412) being female Anopheles. Among these, 91% were morphologically identified as Anopheles funestus s.l., and 5% as Anopheles gambiae s.l. Catches progressively decline in each consecutive trapping month as the environment became drier. This decline was much slower in Malangano, the community next to the dam, with abundance being notably higher in June and July. Further, the majority of An. gambiae s.l. were caught in May, with none identified in July and August. Anopheles larvae were found both in the impoundment and other smaller water bodies such as irrigation wells in each survey month; however, the presence of these smaller water bodies did not have a significant impact on adult female mosquito catches in the GLMM. The study concludes that proximity to the dam impoundment was the primary driver of differences between survey communities with the abundance in Chikhombwe (~1 km away) and Chiponde (~2 km away) being 0.35 (95% confidence interval [CI], 0.19-0.66) and 0.28 (95% CI, 0.16-0.47) lower than Malangano, respectively, after adjusting for other factors. These findings underscore the importance of targeted interventions, such as larval source management or housing improvements, near small dams to mitigate malaria transmission risks during the dry season. Further research is needed to develop cost-effective strategies for vector control within and around these impoundments.

Establishment and evaluation of a qPCR method for the detection of pfmdr1 mutations in Plasmodium falciparum, the causal agent of fatal malaria

Drug resistance surveillance is a major integral part of malaria control programs. Molecular methods play a pivotal role in drug resistance detection and related molecular research. This study aimed to develop a rapid and accurate detection method for drug resistance of Plasmodium falciparum (P. falciparum). A quantitative real-time PCR (qPCR) assay has been developed that identifies the mutation at locus A256T in the P.falciparum multi-drug resistance(pfmdr1) gene producing amino acid change at position 86. The results of 198 samples detected by qPCR were consistent with nested PCR and sequencing, giving an accuracy of 94.3%. The sensitivity, specificity, positive and negative predictive value of qPCR were 85.7%, 97.6%, 90.0% and 96.4%, respectively. The results of qPCR are basically consistent with the nested PCR, which is expected to replace the nested PCR as a new molecular biological method for drug resistance detection, providing reliable technical support for global malaria prevention and control.

Mathematical Assessment of the Role of Intervention Programs for Malaria Control

Malaria remains a global health problem despite the many attempts to control and eradicate it. There is an urgent need to understand the current transmission dynamics of malaria and to determine the interventions necessary to control malaria. In this paper, we seek to develop a fit-for-purpose mathematical model to assess the interventions needed to control malaria in an endemic setting. To achieve this, we formulate a malaria transmission model to analyse the spread of malaria in the presence of interventions. A sensitivity analysis of the model is performed to determine the relative impact of the model parameters on disease transmission. We explore how existing variations in the recruitment and management of intervention strategies affect malaria transmission. Results obtained from the study imply that the discontinuation of existing interventions has a significant effect on malaria prevalence. Thus, the maintenance of interventions is imperative for malaria elimination and eradication. In a scenario study aimed at assessing the impact of long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS), and localized individual measures, our findings indicate that increased LLINs utilization and extended IRS coverage (with longer-lasting insecticides) cause a more pronounced reduction in symptomatic malaria prevalence compared to a reduced LLINs utilization and shorter IRS coverage. Additionally, our study demonstrates the impact of localized preventive measures in mitigating the spread of malaria when compared to the absence of interventions.

Insufficient duration of insecticidal efficacy of Yahe® insecticide-treated nets in Papua New Guinea

BackgroundInsecticide-treated nets (ITNs) are the backbone of anti-malarial vector control in Papua New Guinea (PNG). Over recent years the quality and performance of ITNs delivered to PNG decreased, which has likely contributed to the stagnation in the malaria control effort in the country. The present study reports results from the first 24 months of a durability study with the ITN product Yahe LN® in PNG.MethodsThe durability study was conducted in four villages on the northern coast of PNG, in an area with high malaria parasite transmission, following WHO-recommended methodology adapted to the local scenario. A cohort of n = 500 individually identifiable Yahe® ITNs was distributed by the PNG National Malaria Control Programme from October to December 2021. Insecticidal efficacy of the ITNs was tested using cone bioassays with fully pyrethroid susceptible Anopheles farauti colony mosquitoes at baseline and at 6 months intervals, alongside evaluation of physical integrity and the proportion of ITNs lost to follow-up. A questionnaire was used to collect information on ITN end user behaviour, such as the frequency of use and washing. The observations from the durability study were augmented with simulated laboratory wash assays.ResultsGradual uptake and replacement of previous campaign nets by the communities was observed, such that at 6 months 45% of all newly distributed nets were in use in their designated households. Insecticidal efficacy of the Yahe® nets, expressed as the percent 24 h mortality in cone bioassays decreased from 91 to 45% within the first 6 months of distribution, even though > 90% of study nets had never been washed. Insecticidal efficacy decreased further to < 20% after 24 months. ITNs accumulated physical damage (holes) at a rate similar to previous studies, and 35% were classified as ‘too torn’ by proportional hole index after 24 months. ITNs were lost to follow-up such that 61% of cohort nets were still present after 24 months. Laboratory wash assays indicated a rapid reduction in insecticidal performance with each consecutive wash such that average 24 h mortality was below 20% after 10 washes.ConclusionYahe® ITNs are not performing as per label claim in an area with fully pyrethroid susceptible vectors, and should be investigated more comprehensively and in other settings for compliance with currently recommended durability and efficacy thresholds. The mass distribution of low quality ITN products with variable performance is one of the major ongoing challenges for global malaria control in the last decade.