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Larval source management (LSM) has a long history of advocacy and successes but is rarely adopted where funds are limited. The World Health Organization (WHO) guidelines on malaria prevention recommend the use of LSM as a supplementary intervention to the core vector control methods (insecticide-treated nets and indoor residual spraying), arguing that its feasibility in many settings can be limited by larval habitats being numerous, transient, and difficult to find or treat. Another key argument is that there is insufficient high-quality evidence for its effectiveness to support wide-scale implementation. However, the stagnation of progress towards malaria elimination demands that we consider additional options to the current emphasis on insecticidal commodities targeting adult mosquitoes inside homes. This letter is the result of a global, crossdisciplinary collaboration comprising: (a) detailed online expert discussions, (b) a narrative review of countries that have eliminated local malaria transmission, and (c) a mathematical modeling exercise using two different approaches. Together, these efforts culminated in seven key recommendations for elevating larval source management as a strategy for controlling malaria and other mosquito-borne diseases in Africa (Box 1 ). LSM encompasses the use of larvicide (a commodity) as well as various environmental sanitation measures. Together, these efforts lead to the long-term reduction of mosquito populations, which benefits the entire community by controlling both disease vector and nuisance mosquitoes. In this paper, we argue that the heavy reliance on large-scale cluster-randomized controlled trials (CRTs) to generate evidence on epidemiological endpoints restricts the recommendation of approaches to only those interventions that can be measured by functional units and deliver relatively uniform impact and, therefore, are more likely to receive financial support for conducting these trials. The explicit impacts of LSM may be better captured by using alternative evaluation approaches, especially high-quality operational data and a recognition of locally distinct outcomes and tailored strategies. LSM contributions are also evidenced by the widespread use of LSM strategies in nearly all countries that have successfully achieved malaria elimination. Two modelling approaches demonstrate that a multifaceted strategy, which incorporates LSM as a central intervention alongside other vector control methods, can effectively mitigate key biological threats such as insecticide resistance and outdoor biting, leading to substantial reductions in malaria cases in representative African settings. This argument is extended to show that the available evidence is sufficient to establish the link between LSM approaches and reduced disease transmission of mosquito-borne illnesses. What is needed now is a significant boost in the financial resources and public health administration structures necessary to train, employ and deploy local-level workforces tasked with suppressing mosquito populations in scientifically driven and ecologically sensitive ways. In conclusion, having WHO guidelines that recognize LSM as a key intervention to be delivered in multiple contextualized forms would open the door to increased flexibility for funding and aid countries in implementing the strategies that they deem appropriate. Financially supporting the scale-up of LSM with high-quality operations monitoring for vector control in combination with other core tools can facilitate better health. The global health community should reconsider how evidence and funding are used to support LSM initiatives. Graphical Abstract

Vector-borne diseases, particularly arboviral diseases transmitted by mosquitoes (e.g. dengue, Zika and chikungunya), have (re)emerged globally with increasing prevalence and severity. Climatic and environmental changes have resulted in significant expansion of the geographical distribution of Aedes mosquito vectors to unprecedented levels, creating optimal conditions for their introduction and establishment in new areas, especially in Africa. The prevention of Aedes -borne diseases relies heavily on controlling vector populations. However, the global resurgence of dengue underscores the limitations of current vector control tools in preventing epidemics, highlighting the urgent need for affordable, scalable and community-based vector control measures to address Aedes -borne diseases and urban mosquito vectors (e.g. Aedes spp. and Anopheles stephensi ), with the overall aim to improve public health and well-being. In this report, we summarize the main outcomes of the “International conference on advances in surveillance and control methods for Aedes -borne diseases and urban vectors” held in Dar es Salaam, Tanzania, 26–28 August 2024. The conference aimed to facilitate knowledge exchange, promote collaborative research and drive innovation in the surveillance and control of Aedes -borne diseases in Africa. Key objectives included reviewing the performance of new tools and technologies for Aedes control, and fostering inter-sectoral and international collaborations to strengthen public health measures against mosquito-borne diseases. The event was attended by more than 200 participants from 20 nationalities/countries and was streamed live online, with 321 virtual accesses recorded during the 3-day event. Graphical Abstract

Mosquito-borne diseases remain a significant global health burden, prompting continuous efforts to develop effective mosquito control strategies. Use of chemical insecticides has remained a cornerstone in suppressing mosquito vector populations in the past few decades. However, prolonged reliance, uncontrolled use of chemical insecticides and associated selection pressure on vector populations have resulted in the emergence and spread of insecticide resistance (IR), jeopardizing control efforts. This review explores the potential impact of IR on mosquito behaviour along with effects on vectorial capacity, and endosymbiotic microflora and tries to assess its subsequent implications in vector control interventions. It is discussed how IR may indirectly influence vector competence and disease transmission by altering behaviours such as feeding patterns, resting preferences, and host-seeking activity. Understanding these intricate relationships is crucial for developing robust and sustainable vector management strategies that can effectively combat the challenge of VBDs in the face of evolving resistance patterns.

This investigation was initiated to control Aedes aegypti and Zika virus transmission in Caguas City, Puerto Rico, during the 2016 epidemic using Integrated Vector Management (IVM), which included community awareness and education, source reduction, larviciding, and mass-trapping with autocidal gravid ovitraps (AGO). The epidemic peaked in August to October 2016 and waned after April 2017. There was a preintervention period in October/November 2016 and IVM lasted until August 2017. The area under treatment (23.1 km2) had 61,511 inhabitants and 25,363 buildings. The city was divided into eight even clusters and treated following a cluster randomized stepped-wedge design. We analyzed pools of female Ae. aegypti adults for RNA detection of dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) viruses using 360 surveillance AGO traps every week. Rainfall, temperature, and relative humidity were monitored in each cluster. Mosquito density significantly changed (generalized linear mixed model; F8, 14,588 = 296; P < 0.001) from 8.0 ± 0.1 females per trap per week before the intervention to 2.1 ± 0.04 after the percentage of buildings treated with traps was 60% and to 1.4 ± 0.04 when coverage was above 80%. Out of a total 12,081 mosquito pools, there were 1 DENV-, 7 CHIKV-, and 49 ZIKV-positive pools from October 2016 to March 2017. Afterward, we found only one positive pool of DENV in July 2017. This investigation demonstrated that it was possible to scale up effective Ae. aegypti control to a medium-size city through IVM that included mass trapping of gravid Ae. aegypti females.

Background Early evening and outdoor biting by vector mosquitoes undermines the effectiveness of insecticide-treated nets (ITNs), as users of nets are exposed to vector biting whilst not under a net, both outdoors and indoors. This study assessed exposure to malaria vector bites amongst users and non-users of ITNs in southwestern Mali. Methods Using cross-sectional household survey data of human behaviour and malaria infection prevalence, along with mosquito human landing catch (HLC) data collected in 30 separate communities, the average number of Anopheles gambiae sensu lato (s.l.) mosquito bites per person per night (bppn) received outdoors and indoors were estimated for each survey respondent. The proportion of bites that were not preventable by using a net, the relative contributions of outdoor and indoor residual biting, and the risk factors for exposure to vector bites were estimated. Results Despite very high use of nets (93.2%), malaria infection prevalence was 34% overall. A large proportion of respondents (78%) reported being outdoors at 8 pm, but by midnight, 98% were indoors. Net users were exposed to indoor biting for 1 h, on average, between going indoors and going to bed. For 91%, the net used was an ITN. Human biting rates peaked between 2 and 4 am, when most people (90%) were in bed. Individuals using a net received 11.2 bppn in total, of which 7.1 bppn (63%) occurred outdoors. Those not using a net received almost 10 times the number of bites indoors as net users (38.4 bppn versus 4.0 bppn). The total number of bites received by net users was about one third the total number of bites received by non-net users, indicating the proportion of bites not preventable by use of a net alone. Risk factors for biting exposure included not using a net, going indoors late, location near the river and age over 15 years. Conclusions ITNs substantially reduce exposure to indoor biting, but in this setting, net users still received a large number of Anopheles mosquito bites, giving rise to high malaria infection prevalence despite near-universal net use. Most residual biting occurred outdoors, but about a third still occurred with individuals indoors before going under a net. Effective interventions that reduce residual outdoor and indoor biting are necessary to reduce the high malaria burden in settings like southwestern Mali. Graphical Abstract

Background Vector control plays a critical role in the prevention, control and elimination of vector-borne diseases, and interventions of vector control continue to depend largely on the action of chemical insecticides. A global survey was conducted on the management practices of vector control insecticides at country level to identify gaps to inform future strategies on pesticide management, seeking to improve efficacy of interventions and reduce the side-effects of chemicals used on health and the environment. Methods A survey by questionnaire on the management practices of vector control insecticides was disseminated among all WHO Member States. Data were analysed using descriptive statistics in MS Excel. Results Responses were received from 94 countries, or a 48% response rate. Capacity for insecticide resistance monitoring was established in 68–80% of the countries in most regions, often with external support; however, this capacity was largely lacking from the European & Others Region (i.e. Western & Eastern Europe, North America, Australia and New Zealand). Procurement of vector control insecticides was in 50–75% of countries taking place by agencies other than the central-level procuring agency, over which the central authorities lacked control, for example, to select the product or assure its quality, highlighting the importance of post-market monitoring. Moreover, some countries experienced problems with estimating the correct amounts for procurement, especially for emergency purposes. Large fractions (29–78%) of countries across regions showed shortcomings in worker safety, pesticide storage practices and pesticide waste disposal. Shortcomings were most pronounced in countries of the European & Others Region, which has long been relatively free from mosquito-borne diseases but has recently faced challenges of re-emerging vector-borne diseases. Conclusions Critical shortcomings in the management of vector control insecticides are common in countries across regions, with risks of adverse pesticide effects on health and the environment. Advocacy and resource mobilization are needed at regional and country levels to address these challenges.

Malaria control in sub-Saharan Africa faces significant challenges from biological threats, such as insecticide resistance and adaptive vector behaviours, as well as increasing financial constraints, which necessitate strategic intervention planning to maximize impact. This study assesses the effectiveness of combining vector control methods, case management, and immunoprevention to reduce malaria in Tanzania, considering varying intensities of insecticide resistance in the main vector species. A compartmental model was developed to simulate malaria transmission, incorporating the dominant vectors: Anopheles funestus (anthropophilic and endophilic) and Anopheles arabiensis (zoophilic and exophilic). The model was used to analyse the impacts of insecticide-treated nets (ITNs), indoor residual spraying (IRS), and biolarvicides, used singly or in combinations, under varying intensities of pyrethroid resistance. The analysis was further expanded to explore the impacts of adding case management (treatment using artemisinin-based combinations) and immunization (RTS,S/AS01 and R21/Matrix-M vaccines). At moderate levels of pyrethroid resistance (50%), achieving at least 71% ITN coverage combined with either 50% IRS or 32% biolarvicide coverage reduces the effective reproduction number ( ) to below 1. However, at high resistance levels (exceeding 75%), the effective reproduction number ( ) consistently remains above 1, irrespective of the type or combination of vector control interventions. Adding immunization ( 40% coverage) to ITNs (80% coverage), along with effective treatment (80% coverage), can further reduce the proportion of infectious individuals to <20% and below 1, even under high resistance intensities. Compared to ITNs alone, combining ITNs with IRS and/or biolarvicides greatly improves malaria control at low to moderate intensities of pyrethroid resistance but yields no additional benefits at high resistance intensities. However, integrating these vector control strategies with immunization and effective case management using artemisinin-based combination therapy (ACT) further enhances impact by reducing both parasite transmission and the infectious reservoir.

Background Vector-borne diseases remain a major global health problem, mostly in tropical and subtropical areas. Effective vector control is crucial for controlling vector borne diseases (VBDs). Over the years various vector control tools and strategies have been employed globally. However, the recent challenges including insecticide-resistant, alterations in vector behaviour, and non-target effects have highlighted the need for novel vector control tools and alternate strategies. One such tool is the Attractive Targeted Sugar Baits (ATSBs), which uses the sugar-seeking habit of adult mosquitoes. The ATSB strategy operates on an “attract and kill” approach, where mosquitoes are lured to the bait and to feed on sugar combined with an insecticide. For this, a standard methodology needs to be developed for a uniform evaluation of ATSBs. Results The ATSB vector control strategy has shown promising results in studies carried out in various parts of Africa and the Middle East on controlling populations of mosquito species. Although numerous experiments have been conducted and are ongoing in various countries, there remains a lack of standardized guidelines for evaluating ATSBs. In 2023, the ICMR along with partners drafted the 3rd edition of Common Protocols for evaluating public health vector control products. The revised edition included a trial methodology for ATSB. Taking this into consideration, the phase-wise standard methodology is presented in this review for the uniform evaluation of different formulations/products of ATSBs. Conclusions The methodologies, outlined in this article will serve as the standard methodology for testing ATSB formulations/products under laboratory conditions (Phase I), small-phase (Phase II), and large-phase field trial (Phase III) conditions.

Community engagement strategies provide tools for sustainable vector-borne disease control. A previous cluster randomized control trial engaged nine intervention communities in seven participatory activities to promote management of the domestic and peri-domestic environment to reduce risk factors for vector-borne Chagas disease. This study aims to assess the adoption of this innovative community-based strategy, which included chickens’ management, indoor cleaning practices, and domestic rodent infestation control, using concepts from the Diffusion of Innovations Theory. We used questionnaires and semi-structured interviews to understand perceptions of knowledge gained, intervention adoption level, innovation attributes, and limiting or facilitating factors for adoption. The analysis process focused on five innovation attributes proposed by the Diffusion of Innovations Theory: relative advantage, compatibility, complexity, trialability, and observability. Rodent management was highly adopted by participants, as it had a relative advantage regarding the use of poison and was compatible with local practices. The higher complexity was reduced by offering several types of trapping systems and having practical workshops allowed trialability. Observability was limited because the traps were indoors, but information and traps were shared with neighbors. Chicken management was not as widely adopted due to the higher complexity of the method, and lower compatibility with local practices. Using the concepts proposed by the Diffusion of Innovations Theory helped us to identify the enablers and constraints in the implementation of the Chagas vector control strategy. Based on this experience, community engagement and intersectoral collaboration improve the acceptance and adoption of novel and integrated strategies to improve the prevention and control of neglected diseases.

Background Indoor residual spraying (IRS) remains a core malaria vector control intervention, but widespread insecticide resistance threatens its effectiveness. VECTRON™ T500, containing broflanilide, represents a novel IRS product with a new mode of action targeting GABA receptors. Methods A two-arm non-inferiority study was conducted in Bar Olengo, Siaya County, Kenya, between June and November 2024. Twenty-five structures per arm were sprayed with either VECTRON™ T500 (100 mg a.i/m 2 ) or Actellic™ 300CS (1 g a.i/m 2 ), with five water-sprayed controls. Residual efficacy was assessed using world health organization (WHO) cone bioassays with pyrethroid-resistant Anopheles gambiae sensu stricto ( s.s .) Bungoma strain and susceptible Kisumu strain monthly for six months. Wild vector susceptibility to insecticides, community acceptability, and adverse events were evaluated. Results VECTRON™ T500 maintained significantly higher mortality than Actellic™ 300CS throughout six months on both wall types. Against resistant An. gambiae s.s. Bungoma strain, VECTRON™ T500 achieved 98.73 ± 3.51% mortality (95% CI 97.95–99.51%) compared to 80.22 ± 11.23% for Actellic™ 300CS (95% CI 77.72–82.72%; t₇₈ = − 10.15, p < 0.001, Cohen's d = 2.27). For susceptible Kisumu strain, VECTRON™ T500 maintained 100% mortality versus 89.60 ± 6.34% for Actellic™ 300CS (95% CI 88.19–91.01%; t₇₈ = 10.53, p < 0.001, Cohen's d = 2.38). Actellic™ 300CS efficacy declined below 80% after month 4, while VECTRON™ T500 remained > 95% effective throughout. Wild An. gambiae sensu lato ( s.l .) and Anopheles funestus s.l. showed 100% susceptibility to broflanilide with no cross-resistance detected. No adverse events occurred in VECTRON™ T500 households versus 8% (12/150) in Actellic™ 300CS households. Community acceptance was 100% for VECTRON™ T500 versus 99.33% (149/150) for Actellic™ 300CS, though this difference was not statistically significant. Conclusions VECTRON™ T500 demonstrated superior residual efficacy, excellent safety profile, and high community acceptance compared to Actellic™ 300CS. Its novel mode of action and absence of cross-resistance to pirimiphos-methyl and pyrethroids make it valuable for insecticide resistance management in malaria vector control programmes.