Impact case studies 

Over the past century, there are many examples of research conducted by PHEG members that has underpinned major public health achievements. Here, we highlight some key case studies demonstrating how our research has helped inform policy and improve health worldwide. 

The development and evaluation of dual-active ingredient mosquito nets and residual insecticides for malaria control

Research led by members of PHEG and international partners has been instrumental in bringing new vector control tools to market, helping combat insecticide resistance in malaria vectors. 

For several decades, low profit margins disincentivized the development of new insecticides for public health, leading to an overreliance on a limited portfolio of compounds for malaria control. This lack of innovation has contributed to a rise in insecticide resistance in malaria vector populations which is undermining the efficacy of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), posing a significant threat to control progress. Over the past 15 years, strategic collaborations between academics at LSHTM, the WHO and industrial partners have been pivotal in overcoming economic barriers to the development of new vector control products and combatting insecticide resistance. 

The most important achievement of this work was the recent WHO recommendation of new LLIN products containing a combination of active ingredients. Academics from LSHTM were involved in this research from the beginning, leading proof-of-concept laboratory and semi-field studies to assess whether candidate compounds were effective against insecticide-resistant mosquitoes and suitable for use on LLINs. These preliminary studies led to the development of several prototype LLIN products containing a standard pyrethroid insecticide and a second compound effective against resistant mosquitoes. While results from subsequent field evaluations of these LLINs were promising, the WHO requested robust evidence from randomised epidemiological trials to build the evidence base for their deployment.

In the years following, a series of cluster-randomised controlled trials were conducted in Benin and Tanzania to assess the epidemiological impact of these novel LLINs. These trials generated high-quality evidence for the public health value of two of the candidate nets, namely pyrethroid-piperonyl butoxide (PBO) and pyrethroid-chlorfenapyr LLINs. Based on this, WHO has recommended the deployment of both net types in malaria-endemic countries, leading to a substantial scale-up in coverage in recent years. As of 2025, 83% of all LLIN shipments in sub-Saharan Africa were for new LLIN types and recent modelling studies suggest that switching to new LLINs could avert up to 75% more malaria cases compared to use of standard tools. 

In addition to LLINs, research by PHEG members has also helped bring several new IRS insecticides to market. Although the use of IRS has declined in recent years due to funding constraints, it remains highly effective in controlling malaria when implemented properly. In collaboration with Mitsui Chemicals and the Innovative Vector Control Consortium (IVCC), researchers from LSHTM conducted a range of studies spanning the laboratory to the community to evaluate the safety and efficacy of a new IRS formulation (VECTRON T500) containing the meta-diamide insecticide, broflanilide. After early lab studies showed that broflanilide exhibited low toxicity to mammals and was effective against resistant mosquitoes, small- and large-scale field trials were initiated in Benin and Tanzania. These studies demonstrated that VECTRON T500 was highly effective at controlling wild malaria vector populations when sprayed inside households and crucially, continued killing mosquitoes for up to 2 years after application. Based on this evidence, VECTRON T500 was added to the list of WHO-recommended vector control products and is now being used in many countries where IRS is regularly implemented, helping to improve control of insecticide-resistant malaria vectors. 

These case studies represent significant public health achievements underpinned by research conducted by PHEG members. Learn more about the WHO recommendation of new LLINs, or for a broader overview of research at LSHTM on new malaria vector control strategies.

Guideline development for leishmaniasis vector control

Leishmaniasis, a neglected tropical disease caused by Leishmania parasites transmitted by phlebotomine sand flies, remains a serious health problem in many areas. Visceral leishmaniasis, for example, causes 30,000 new cases every year with a high case fatality if left untreated. Although interventions targeting the sand fly vector have formed a core component of leishmaniasis control strategies in recent decades—helping many countries reduce cases to near elimination—vector control is often neglected by control programmes due to challenges in funding and implementation. Recognising the need to strengthen sand fly control and surveillance to accelerate progress towards leishmaniasis elimination, the WHO developed the manual on leishmaniasis vector control, surveillance, monitoring and evaluation in 2023.

Members of PHEG include world-leading experts in leishmaniasis vector control who were asked to lead a panel of international experts to develop the manual. Leveraging their expertise and experience, they contributed directly to its writing, ensuring the guidelines incorporated cutting-edge knowledge on sandfly control and surveillance. Overall, the manual equips control programmes with practical tools, techniques and procedures needed to strengthen sand fly control and surveillance—key to improving leishmaniasis control in affected regions. PHEG’s contribution to these guidelines further demonstrates our commitment to shaping global health policy to reduce the burden of vector-borne disease and save lives.

Guideline development for determining the comparative efficacy of new vector control products

The spread of insecticide resistance in malaria vectors has led to the development of next-generation long-lasting insecticidal net (LLIN) and indoor residual spraying (IRS) products containing new active ingredients. Several of these new types of intervention have been recommended for public health use by WHO after prototype products demonstrated epidemiological and entomological impact in large-scale community randomised trials. In the years following, vector control product manufacturers have continued to innovate, developing new varieties of these products to help fulfill market demand. However, these new products have not undergone the same rigorous evaluation as previous prototypes, and it remains unclear whether they will provide comparable levels of disease control.

Recognising the prohibitive cost and time constraints of repeating cluster-randomised controlled trials with all new products, WHO launched an initiative in 2018 to streamline the evaluation of new products falling within existing intervention categories. As part of this, they published a non-inferiority trial protocol, designed to assess whether new second-in-class LLINs and IRS products perform comparably to the proven first-in-class prototypes. PHEG members played a crucial role in piloting this approach. At LSHTM partner sites in Benin and Tanzania, a variety of next-generation LLIN and IRS products were tested following this design, generating crucial data on their comparative efficacy. Later in 2021 and 2023, researchers from these sites participated in technical consultations with WHO, where they presented efficacy data and shared perspectives on the value of non-inferiority trials for determining the comparative efficacy of new LLIN and IRS products. As a result of this, non-inferiority trials were formally integrated into WHO’s evaluation framework, providing a streamlined process for evidence-based decisions about whether new products can be covered by existing policy recommendations.

Through this work, PHEG members have helped WHO develop rigorous but pragmatic guidelines for determining the comparative efficacy of new vector control products—helping expand access to effective vector control in endemic countries while maintaining high standards of evidence.

Response to the invasion of the urban malaria vector Anopheles stephensi in sub-Saharan Africa 

Despite decades of progress in the control of vector-borne diseases, a range of emerging biological threats now pose a significant risk to sustaining these gains. In malaria control, long-standing challenges such as increasing parasite drug resistance and vector insecticide resistance are being compounded by the recent invasion of Anopheles stephensi—an Asian mosquito vector highly adapted to urban environments—into sub-Saharan Africa. This development represents a critical shift in the epidemiology of malaria on the continent. Unlike traditional African malaria vectors, which are predominantly found in rural settings, An. stephensi thrives in urban areas. Its invasion in Africa thus presents an urgent threat to control, with potential to significantly increase malaria transmission in urban settings.

As key contributors to the Resilience Against Future Threats (RAFT) consortium, PHEG members are at the forefront of efforts to address this threat. RAFT is a research consortium established to generate new evidence for governments and health leaders to ensure that national mosquito strategies are effective in the face of new threats, particularly in Africa. One of its main remits is to generate evidence to help produce a coordinated response to the invasion of An. stephensi. RAFT is doing this through the following activities:

• Conducting entomological and molecular surveillance to detect the presence of An. stephensi in African countries
• Developing and testing eDNA surveillance tools for early detection of An. stephensi
• Carrying out case studies across African countries to assess national preparedness and offer tailored recommendations to mitigate emerging vector-control threats

This work demonstrates the commitment of PHEG members to responding to emerging challenges in vector-borne disease control. Through its involvement in RAFT, PHEG is helping coordinate a response to some of the most significant threats to malaria control—helping ensure the sustainability and effectiveness of control measures for decades to come.

To learn more about the RAFT consortium and their work responding to emerging threats in vector-borne disease control explore these webpages.

To learn more about the RAFT consortium and their work responding to emerging threats in vector-borne disease control, explore this webpage and online presentation.

Engagement with policy and practice actors

As world-leading experts in public health entomology, several of our members hold key advisory and advocacy roles at major health institutions. Notable examples of our engagement with policy and practice actors include:

• Our members regularly serve on World Health Organisation advisory groups, using their expertise to influence global health policy. PHEG members have been part of the: Vector Control Advisory Group, Malaria Policy Advisory Group and a Regional Technical Advisory Group on leishmaniasis elimination in south Asia.
• Our members have also advised Ministries of Health on suitable vector control strategies, most notably for malaria and leishmaniasis control in Benin and India, respectively.
• Our members include the current co-chair of the Roll Back Malaria Partnership’s Vector Control Working Group (VCWG), and one of its founding co-chairs. The VCWG is a collaborative initiative that brings together various stakeholders to advance vector control and malaria elimination efforts. 

Publications

We also create impact by disseminating research in leading scientific journals to advance scientific knowledge. Over the past 5 years, our members have published 178 papers in more than 40 journals. See a full list of our recent publications.