RIVER BLINDNESS

 BACKGROUND

Onchocerciasis, also known as river blindness, is a disease that affects an estimated 21 million people in 31 sub-Saharan countries, with another 218 million people living at risk of contracting the disease. River blindness is caused by the filarial worm Onchocerca volvulus which is transmitted to humans by flies of the Simulium species. In its most severe form, onchocerciasis when left untreated can lead to permanent blindness. This has led WHO to implement numerous programs aimed at controlling and eliminating onchocerciasis as a public health problem, with the WHO 2021-2030 Roadmap for Neglected Tropical Diseases describing the goals for the next decade. Onchocerciasis control and elimination programs rely on annual mass drug administration (MDA) programs with the deworming drug ivermectin that operate on an astounding scale, with over 200 million doses of ivermectin distributed each year. MDA programs critically rely on diagnostic tools to guide decision-making on where to start administering ivermectin, and for how long. However, all currently available diagnostics present some limitations in one way or another.

The limitations of the existing diagnostic tools led WHO to publish two Target Product Profiles (TPPs) in 2021 defining the criteria that new diagnostic tests will need to meet, depending on whether they are used for (a) mapping onchocerciasis in areas of low prevalence and deciding when to start MDA (“Mapping TPP”), or (b) deciding when to stop MDA (“Stopping TPP”). The two TPPs are nearly identical differing only with respect to sensitivity, which must be ≥ 60% to map onchocerciasis and to support decisions to initiate MDA, and ≥ 89% to support decisions to safely stop MDA. Both TPPs require an exquisitely high specificity of ≥ 99.8% which, critically, needs to be demonstrated at the lower bound 95% confidence interval – an extremely challenging criterion. The requirement for this ultrahigh specificity is dictated by the need to detect as little as 1‒2% of disease prevalence with sufficient statistical confidence during onchocerciasis mapping campaigns.

OUR SOLUTION FOR RIVER BLINDNESS

Funding by USAID allowed our partners at Drugs & Diagnostics for Tropical Diseases (DDTD) to develop a rapid test that meets the WHO target product profile for onchocerciasis elimination mapping (OEM) as determined by the Centers for Disease Control and Prevention (CDC) in independent laboratory studies. Field studies in six different African countries with support from COR-NTD, USAID, and the Bill & Melinda Gates Foundation confirmed the excellent diagnostic performance of the test. Big Eye Diagnostics in-licensed the test from DDTD in 2024 and produced a further optimized, design-locked candidate test under an NIH SBIR Direct-to-Phase II grant. We subsequently developed an automated high-throughput manufacturing process meeting ISO-13485:2016 quality standards that allowed us to produce close to 100’000 test units to date.  A recently awarded grant by the BMGF will allow the test to be progressed to regulatory review by WHO’s Expert Review Panel for Diagnostics (ERPD) by the end of 2025, followed by commercialization in 2026.