Dengue is one of the fastest-spreading mosquito-borne viral diseases worldwide. It is caused by four closely related dengue virus serotypes and is transmitted primarily by infected female Aedes aegypti mosquitoes, which are highly adapted to urban environments and frequently breed in small containers holding stagnant water. Climate change may extend the mosquitoes’ geographic and seasonal range, while urban growth, inadequate water and waste management, and international travel can accelerate transmission. Brazil has reported some of the world’s highest dengue case numbers, with the greatest burden often falling on communities already facing economic disadvantage, environmental hazards, and limited access to health services. These overlapping conditions make prevention a complex problem requiring more than a single intervention.

Published in the Cochrane Database of Systematic Reviews, the mapping review is described as the first comprehensive evidence and gap map to consolidate both primary studies and systematic reviews covering dengue prevention strategies. Evidence and gap maps are designed to show where research exists and where it is missing, rather than to estimate one overall treatment effect. The researchers categorized studies according to intervention type and outcome, allowing them to distinguish between evidence on mosquito populations, human infection, illness, vaccination, behaviour, implementation, and adverse effects. This structure is important because a program can reduce mosquito numbers without demonstrably reducing dengue cases, or can be biologically effective while proving too difficult, expensive, or unacceptable to deliver at scale.

Community education emerged as one of the best-documented prevention areas. The map identified 47 randomized trials and 140 non-randomized studies examining efforts to help communities prevent mosquito breeding and reduce exposure to the virus. Such programs may encourage residents to remove standing water, cover household containers, improve waste disposal, inspect yards, or use protective measures. Many initiatives also involve schools, community leaders, local health workers, and neighborhood organizations in an attempt to turn individual actions into sustained collective behaviour. Yet the quantity of research does not necessarily translate into firm conclusions. The evidence remains limited on whether education programs reduce dengue infection or disease at the population level, particularly over long periods and in areas where environmental conditions continuously create new breeding sites.

The map also revealed major synthesis gaps in interventions aimed directly at mosquitoes. Adult-vector control includes insecticide spraying, lethal traps, treated materials, spatial repellents, and newer biological approaches. Existing systematic reviews in this area are generally outdated, although a recent review has examined Wolbachia-based strategies. Wolbachia are naturally occurring bacteria that can be introduced into Aedes mosquitoes, where they may reduce the insects’ ability to transmit dengue virus and can spread through mosquito populations over successive generations. Other approaches target the aquatic or larval stage, including removal of breeding containers, larvicides, habitat modification, and water-management measures. For these interventions, the review found gaps across nearly every outcome category, meaning that evidence has not been consistently assembled for effects on mosquitoes, human behaviour, implementation, or dengue itself.

Vaccination presents a different but equally important challenge. Dengue vaccines have been evaluated in numerous clinical trials, particularly for safety and their ability to prevent symptomatic disease or hospitalization in selected populations. However, the evidence map found little synthesized evidence about how vaccination programs function in real-world adult populations. Introducing a vaccine through routine public-health systems involves questions that clinical trials may not fully answer: how people respond to recommendations, whether eligible groups complete vaccination schedules, how programs reach communities with limited healthcare access, and how vaccine uptake changes during outbreaks. Behavioural outcomes were described as essentially absent in the vaccine evidence base, while implementation evidence remained limited. These gaps make it difficult to predict how vaccination would perform outside tightly controlled research settings.

Environmental interventions were another area in which primary studies exist but high-quality systematic synthesis remains insufficient, especially for behavioural and implementation outcomes. Environmental measures may include improving water supplies so households do not need to store water, strengthening waste collection, redesigning urban drainage, modifying construction practices, and reducing containers that allow mosquitoes to reproduce. Their effects are rarely isolated from broader social and infrastructure changes, which makes them methodologically difficult to study. Researchers must often account for rainfall, temperature, housing density, insecticide use, population movement, and the presence of other vector-control campaigns. Without careful study designs and long-term follow-up, it can be impossible to determine whether a fall in dengue cases resulted from an intervention or from natural fluctuations in transmission.

Policymakers and civil-society representatives participated directly in the mapping process and helped identify priorities for future research. Stakeholders highlighted adverse effects across four intervention areas: environmental interventions, community education, measures targeting aquatic stages of the mosquito, and measures targeting adult vectors. The emphasis on adverse effects is significant because prevention programs can create unintended consequences. Insecticides may expose people or ecosystems to chemical hazards, community campaigns may place additional responsibilities on households, and environmental changes may disrupt livelihoods or require resources unavailable to poorer communities. Understanding these effects alongside benefits is essential for judging whether an intervention is acceptable, equitable, and sustainable rather than merely effective under experimental conditions.

The authors call for updated and comprehensive systematic reviews of vector-control interventions, along with stronger synthesis of implementation and behavioural evidence across non-vaccine strategies. They also argue that adverse effects should be evaluated systematically beyond the vaccine literature. A recurring concern is the field’s reliance on entomological outcomes, such as adult mosquito abundance, larval density, or breeding-site counts. These measurements are useful because they help reveal how an intervention affects the vector, but they are indirect indicators of public-health impact. A lower mosquito count does not automatically mean fewer infections, particularly when mosquito behaviour, virus prevalence, immunity, weather, and human movement change simultaneously. Future studies should therefore prioritize epidemiological outcomes, including laboratory-confirmed dengue, hospitalization, severe disease, and deaths, while also measuring cost, feasibility, coverage, adherence, equity, and long-term community acceptance.

The map was developed with Cochrane Crowd, a citizen-science platform that helps classify research, and with EPPI Reviewer and EPPI Mapper software for coding and visualizing the evidence. Stakeholder engagement was conducted with Instituto Veredas, a Brazilian organization working across public management, academia, and civil society. The resulting interactive map allows researchers, funders, and health officials to explore evidence by intervention and outcome, potentially helping them identify where new trials or systematic reviews would have the greatest value. For dengue-endemic regions, the message is clear: the next phase of prevention science must connect laboratory and entomological findings with measurable reductions in human disease. Without that bridge, the world may continue producing research faster than it can produce answers.

Subject of Research: People

Article Title: Interventions for preventing dengue: a mapping review

News Publication Date: 23-Aug-2026

Web References: https://links.cochrane.org/dengue_map_v1; https://crowd.cochrane.org/; https://eppi.ioe.ac.uk/cms/er4/; https://eppi.ioe.ac.uk/cms/er4/EPPI-Mapper; https://www.veredas.org/

References: Cochrane Database of Systematic Reviews. DOI: 10.1002/14651858.CD016299.pub2

Keywords: Dengue fever, dengue virus, Aedes aegypti, mosquito-borne disease, vector control, Wolbachia, dengue vaccines, community education, environmental interventions, public health, systematic review, evidence and gap map, Brazil, tropical diseases

Mosquitoes are biological vectors: they acquire viruses when feeding on an infected host and can later transmit those viruses through subsequent bites. The capacity of a mosquito population to sustain transmission depends on several interacting factors, including the presence of competent mosquito species, temperature, rainfall, breeding habitats, virus introduction and the availability of humans or animals that can serve as hosts. Warmer conditions can accelerate viral replication inside mosquitoes and shorten the time required for them to become infectious, while changes in rainfall and water management can create new larval habitats. More frequent international travel can also introduce viruses into areas where mosquito populations are present but local transmission has previously been limited or absent.

The European disease landscape has already demonstrated why this issue requires sustained attention. Aedes mosquitoes, which can transmit dengue and chikungunya viruses, have expanded their presence in parts of Europe, while Culex mosquitoes are important vectors of West Nile virus. The establishment of a vector does not automatically lead to an outbreak, because transmission also depends on virus circulation, weather, human behaviour and public-health preparedness. Nevertheless, when suitable mosquitoes and favourable environmental conditions coincide, imported infections can lead to local transmission. The authors therefore describe mosquito control as an essential component of outbreak prevention rather than merely a response used after disease transmission has begun.

The most direct way to reduce mosquito abundance is to eliminate or manage the stagnant water in which larvae develop. Containers, rainwater collection points, blocked drainage systems and other small pools can provide breeding sites for Aedes mosquitoes, while larger wetlands, irrigation structures and urban water systems may support other species. Where water cannot be removed, larvicides can be used to target immature mosquitoes before they emerge as adults capable of biting and transmitting pathogens. During outbreaks, adult mosquitoes may also be targeted with biocidal products. These interventions can reduce vector density rapidly, but their performance depends on local ecology, timing, coverage, application methods and repeated monitoring.

Another approach now being piloted in Europe is the sterile insect technique, or SIT. This method involves mass-rearing male mosquitoes, sterilising them and releasing them into areas where they can mate with wild females. Because the resulting eggs are infertile, repeated releases can reduce the reproductive capacity of the target population. Male mosquitoes do not bite, so the technique is designed to suppress populations without increasing the number of biting insects. SIT may offer a valuable alternative or complement to chemical control, but its effectiveness depends on accurate releases, adequate population coverage and detailed knowledge of mosquito ecology. It also requires assessment of operational costs, long-term sustainability and effects under different environmental conditions.

Chemical control remains important, yet it presents a growing scientific and regulatory challenge. Pyrethroids account for most of the substances approved for adult mosquito control and can interfere with the normal function of insect nervous systems, producing rapid knockdown or death. Their extensive use, however, raises concerns about possible effects on human health and non-target organisms, particularly when applications become broader or more frequent. Mosquito resistance is an additional threat. Genetic changes affecting insecticide target sites, increased detoxification of active compounds or behavioural changes can allow mosquitoes to survive exposure. As resistance increases, products may become less effective, forcing programmes to improve surveillance, rotate control methods and avoid unnecessary applications.

The commentary identifies major gaps in the evidence needed to decide which interventions should be used, where and at what scale. Reliable comparisons of cost-effectiveness remain limited, especially for programmes that combine larval control, adult control, environmental management, personal protection and emerging technologies. A measure that works in one setting may perform poorly elsewhere because mosquito species, housing, infrastructure, climate and community behaviour differ. Countries also vary in the biocidal products they approve and in the rules governing their use. These differences can complicate cross-border responses, procurement and the rapid deployment of control measures when vectors or viruses move across national boundaries.

Personal protection remains an important layer of prevention, even when public authorities are operating mosquito-control programmes. Repellents can reduce the likelihood of bites, while long clothing, window and door screens, and mosquito nets can create physical barriers between people and vectors. Such measures are particularly important for individuals infected with a mosquito-borne virus, because preventing additional bites can reduce the opportunity for mosquitoes to acquire the virus and pass it to others. Personal protection cannot replace population-level control, but it can reduce exposure while surveillance teams investigate transmission and authorities apply targeted interventions.

The authors argue that fragmented governance is one of the greatest obstacles to effective mosquito control. Responsibility commonly rests with ministries of health, although municipal authorities may lead local operations, and ministries responsible for agriculture, the environment, transport or urban development may also influence mosquito habitats and disease risk. Control plans are frequently designed below the national level and implemented by private contractors, creating potential differences in capacity and performance. ECDC surveys conducted in 2020 and 2025 found that 20 of 29 countries reported active mosquito-control measures, with most focusing on larvae. However, the absence of a political perception that mosquito-borne diseases represent an immediate priority can limit investment in surveillance, laboratory capacity, trained personnel and long-term prevention.

At the European level, the response involves institutions with different but complementary responsibilities. ECDC and the European Food Safety Authority provide scientific guidance and surveillance expertise for human and animal health, while ECHA evaluates biocidal substances and products used for mosquito control. The EEA contributes environmental and climate information that can help identify changing conditions and assess risk, and the European Commission supports the implementation of health legislation, vector surveillance, public-health measures, coordination and research funding. The scientists call for these activities to be connected through a One Health framework that includes public health, veterinary medicine, environmental protection and urban planning. By combining information on human cases, animal infections, mosquito abundance, insecticide resistance, climate and land use, Europe could detect emerging risks earlier and select interventions that reduce disease transmission while protecting ecosystems and communities.

Subject of Research:
Not applicable

Article Title:
Strengthening mosquito control to manage emerging mosquito-borne diseases

News Publication Date:
20 August 2026

Web References:
https://doi.org/10.2807/1560-7917.ES.2026.31.33.2600306

References:
Briet et al., “Strengthening mosquito control to manage emerging mosquito-borne diseases,” Eurosurveillance, published 20 August 2026. DOI: 10.2807/1560-7917.ES.2026.31.33.2600306

Keywords:
Mosquito control, mosquito-borne diseases, dengue, chikungunya, West Nile virus, vector-borne disease, insecticide resistance, pyrethroids, sterile insect technique, One Health, Europe, ECDC, ECHA, EEA