LOA LOA

 BACKGROUND

Big Eye Diagnostics has delivered an ultra-specific serological rapid test for onchocerciasis [Link to internal Tab] that is on track to being commercialized for onchocerciasis elimination mapping (OEM) in early 2026. The next major challenge is that onchocerciasis cannot be fully addressed until a test for Loa loa is also commercialized. This is because onchocerciasis elimination programs rely on mass drug administration of ivermectin (IVM), a drug that has an exceptional safety profile in most circumstances, except in people heavily co-infected with Loa loa, another filarial worm. In this case, IVM can cause severe adverse events (SAEs) and even be lethal. The risk of such severe SAEs occurs only in individuals with > 30,000 L. loa microfilariae per mL of blood – yet, dramatically, over 200 people have already died in national onchocerciasis programs due to undetected heavy co-infection with L. Loa.

Consequently, in the absence of a suitable diagnostic for loiasis, entire areas or even countries such as Gabon, where onchocerciasis and loiasis are co-endemic, are currently not addressed by the IVM MDA programs. Understandably, the Mectizan donation program, the arm of Merck that donates over 100 million doses of IVM annually to support the RB programs, will not provide drugs in areas where Merck may be liable for additional deaths. This conundrum makes it impossible to truly eliminate river blindness as a public health problem from the African continent.

A NEW ANTIGEN TEST FOR LOIASIS

Against this backdrop, we set out to develop an exclusion test allowing to determine active infection by L. loa in areas where onchocerciasis and loiasis are co-endemic. Under an NIH Phase I Contract, we managed to generate prototype tests able to detect two specific antigens of L. loa discovered by our partners at Washington University in St. Louis (WUSTL) . The prototype tests are being optimized with the goal to maximize positive signal strength versus non-specific binding. The best LFAs resulting from these efforts will be evaluated against patient plasma by the WUSTL team, and the quantitative data (test line intensities measured with a benchtop reader) will be used to determine whether the best assay format to be progressed further is a monoplex test with only one of the two antigens, or a biplex test involving both antigens.