DISSECT: Developing innovative scalable solutions to entomology gaps and cross-border transmission of onchocerciasis

The DISSECT project was a large-scale research project led by Sightsavers, in collaboration with health ministries and research partners in Malawi, Mozambique, Ghana and Côte d’Ivoire, as well as the Global Institute for Disease Elimination (GLIDE) as funder and technical partner.

The primary objective was to address four critical gaps that each form a barrier to onchocerciasis elimination, with a specific focus on cross-border transmission areas:

• Lack of operational guidance for standardised entomological data collection
• The need to replace human landing capture with a safer, more standardised alternative
• Outdated methods of breeding site identification and monitoring
• The need to improve capacity for analysing entomological samples within endemic countries

To bridge those gaps, the specific objectives of the project were to:

• 1.1 Develop a standardised entomology data collection toolkit for breeding site identification and transmission assessment
• 1.2 Develop an optimized blackfly trap
• 1.3 Develop an updated approach to breeding site prediction and validation
• 1.4 Establish regional centres of excellence for programmatic entomological analysis
• 2.1 Understand the potential of traps for vector control
• 2.2 Understand the opportunities for integration with other insects and diseases

Background

Onchocerciasis is endemic in 26 African countries, Yemen, and two countries in Latin America (WHO 2025). More than 250 million people live in at-risk areas across these 29 endemic countries, with 99% of all cases occurring in African foci (WHO 2025).

The World Health Organization’s (WHO) 2030 NTD roadmap sets a target to eliminate onchocerciasis through interruption of transmission, with a milestone stating that all 29 endemic countries should have stopped mass drug administration (MDA) in one or more foci by 2030 (WHO 2020). Despite this ambitious aim, there are several significant barriers to achieving onchocerciasis elimination:

Lack of operational guidance for collection of elimination-critical entomological data: The WHO criteria for verifying interruption of transmission of onchocerciasis and stopping MDA are reliant on entomological thresholds, and recommendations on post-treatment and post-elimination surveillance strategies are entirely entomology based. Despite this there is little operational guidance to inform and standardise deployment of current techniques in the field. This poses a serious barrier to onchocerciasis elimination.

The need to replace human landing capture with a safer, more standardised alternative: At the inception of the project, there were no blackfly entomological monitoring and evaluation technologies available for programmatic use at scale. Current approaches for verification of onchocerciasis elimination rely on the use of outdated human landing capture (HLC); a time-consuming, laborious, and ethically questionable technique that requires local people with minimum training to expose themselves to potentially infectious blackfly bites for prolonged periods of time.

Programmatic identification and monitoring of blackfly breeding sites is poorly understood: In the 1970s, techniques for identification of blackfly breeding sites were developed and used to identify breeding sites for larviciding. These techniques have not been updated much since. They are time consuming, and don’t take into consideration the current wide availability of satellite and environmental data that could be used to refine and target collection of data on the ground.

The need to improve capacity for analysing entomological samples within endemic countries: Currently, there are only laboratory-based diagnostic tests available to accurately measure WHO elimination thresholds for onchocerciasis. While rapid diagnostic tests (RDTs) are in the final stages of development to measure the serological threshold, there are no field-friendly diagnostic tests on the horizon to measure the entomological threshold. Therefore, it is crucial to maintain strong, high-quality laboratory capacity in onchocerciasis-endemic countries. This capacity supports short-term assessments of serological thresholds and is especially important for monitoring entomological thresholds, as well as meeting post-elimination and post-validation surveillance needs for onchocerciasis elimination.

The DISSECT project aimed to develop standardised and scalable onchocerciasis entomological data collection tools. In doing so, the project was also able to support countries to assess cross-border onchocerciasis transmission, and generate high-quality data for elimination dossiers and programmatic decision-making.

1.1 Develop a standardised entomology data collection toolkit

DISSECT developed and piloted a toolkit to operationalise the guidance within the WHO entomological manual for onchocerciasis elimination programmes specifically for the collection of high-quality data from the field. The toolkit was drafted and refined in a series of participatory workshops, and then piloted successfully in all four DISSECT countries.

The results from these pilot data collections showed that the toolkit was accessible and easy-to-use by individuals with varying scientific backgrounds, and resulted in the collection of high-quality data from cross-border areas. This is a valuable tool for countries to help them adhere to WHO guidance, and collect the data they need to measure progress towards onchocerciasis elimination.

1.2 Developing an optimised blackfly trap

One of the main aims of DISSECT was to optimise the design of the Esperanza Window Trap (EWT) to increase their efficiency in catching blackflies. Different size, shape, colour, and odour attractant combinations were tested. Once the best EWT designs were determined, we found that seven pairs of these optimised traps could perform as effectively as one human flycatcher. The traps are easy to set up and require minimal maintenance in the field. Ultimately we are hoping this will bring an end to the use of unethical human landing catches to collect adult blackflies to assess onchocerciasis elimination.

1.3 Updated breeding site identification tool

To modernise the detection of blackfly breeding sites along rivers, DISSECT used freely available satellite data and machine learning to develop a tool for predicting the distribution of blackfly breeding sites. Our aim was to improve the process for characterising transmission sites, with a lower cost and greater safety, by reducing the amount of time spent physically searching rivers for blackflies. The final model achieved an accuracy of 83.1% and an area under the curve of 0.86, indicating excellent predictive performance.

The model was able to exclude low-risk areas from needing physical inspections. This allows field teams to focus time and resources physically inspecting high-probability sites. This is particularly valuable for programmes operating in resource-constrained or cross-border settings, where logistical and security challenges can hinder traditional survey methods.

1.4 Establish regional centres of excellence for programmatic entomological analysis

Four national laboratories, one in each of the four DISSECT countries, were identified and supported through targeted training and capacity building. Training on the laboratory techniques used to measure onchocerciasis elimination thresholds and understand onchocerciasis transmission was delivered. This included training on cytotaxonomy, Ov16 lab RDT protocol, and the O-150 PCR-ELISA protocol.

There were a lot of learnings around procurement challenges and international supply chains, which have impacts far beyond this project and highlight the need for systematic change. The project was lucky to work with dedicated and skilled teams in each of the four labs. We are confident that capacity has been meaningfully strengthened in all four countries, and that each laboratory has the potential to serve as a regional centre of excellence for programmatic entomological analysis.

2.1 Understanding the potential of traps for vector control

After optimisation, the best EWT trap designs were deployed at a higher than usual density, to measure their impact on local blackfly biting rates. Biting rates were assessed using human landing capture before and after the high-density trapping exercise. Biting rate reductions were most significant in Malawi.

Across all the DISSECT countries, this component of the research showed that in African settings, EWTs effectively reduce human biting rates, making them a promising, sustainable vector control tool for lowering onchocerciasis transmission. This can enhance elimination efforts when combined with MDA using ivermectin. Our findings suggest that higher trap densities and longer deployment periods may increase the impact on blackfly populations.

2.2 Understanding opportunities for integration with other insects and diseases

For this strand of the research there was enhanced evaluation of EWT blackfly traps, to quantify the other insects caught on them, as well as co-deployment of mosquito traps in communities at the same time as blackfly traps. The findings showed that EWTs deployed in riverine settings effectively catch other vector species of human and animal health relevance. This boosts the significance of the trapping operation, as with no extra expenditure, information can be quantified and reported to the relevant departments alongside the onchocerciasis and NTD leads.

Further, the blackfly trapping teams in all four countries of study succeeded in deploying mosquito traps. The catches from these additional traps were effectively evaluated and identified in the community alongside blackfly trapping work. This opens the door to integrated malaria and onchocerciasis studies in future, as the feasibility of co-deployment and management of both types of trap by the same teams has been demonstrated here.

• Our data collection toolkit could help to standardise the way entomology data is collected and analysed by onchocerciasis elimination programmes across different countries. It will help countries follow WHO guidance when conducting field data collection
• A sensitive and specific model predicting the presence of blackfly breeding sites has been successfully developed. This has the potential to improve the efficiency of entomological surveys, by helping field teams focus on high probability areas and avoid low-likelihood zones
• The development of optimised blackfly traps could influence and support ministries of health and WHO to move away from reliance on outdated human landing capture
• In future, countries may also be able to use the optimised traps to reduce blackfly bites, decreasing the risk of contracting onchocerciasis that is faced by communities
• This project has demonstrated how onchocerciasis entomological data collection can be integrated with other diseases. This will help government and policymakers plan strategies and interventions in resource constrained settings
• Valuable entomological and epidemiological onchocerciasis data was collected from four cross-border areas in Malawi, Mozambique, Ghana and Cote D’Ivoire. This data supports each country to have an accurate estimate of the progress towards onchocerciasis elimination in these areas
• Overall, this study could advance global progress towards the elimination of onchocerciasis as a public health problem