Evaluation of a novel biplex rapid diagnostic test for antibody responses to Loa loa and Onchocerca volvulus infections in Congo (2022-2023)

Loiasis, a disease caused by the parasite Loa loa impacting approximately 10 million people in Central Africa, causes transient angioedemas called Calabar swellings and eye worm episodes. Treatment is challenging, particularly in regions where onchocerciasis, another type of filariasis, is also prevalent. We tested a new kind of test that can detect both diseases at once and compared its performance with a previously available test for loiasis. We took blood samples from 971 people living in an area of Congo where loiasis is endemic. Out of the participants, 35.4% had L. loa pre-larvae in the blood – known as microfilariae, and 72.0% had experienced loiasis-related signs. The new test demonstrated promise in detecting the disease, albeit with some likelihood of false positives. Additionally, its performance varied according to the density of microfilariae in the blood. While the results exceeded expectations, further testing is essential to ensure its reliability. If validated, this test could prove instrumental in diagnosing both loiasis and onchocerciasis, offering a valuable tool for public health interventions in affected regions.