Field Evaluation of Feasibility & Ease-of-Use of Novel Onchocerciasis Diagnostics - Benin

In 2023, the World Health Organization (WHO) established a new roadmap for the elimination of several neglected tropical diseases (NTDs) by 2030. Onchocerciasis is one of the NTDs targeted for elimination on this roadmap. Benin is endemic for onchocerciasis, and has received several decades of treatment already. Elimination is confirmed through several phases, with decision-making based on the results of serological and entomological assessments. These assessments involve significant logistics, relying on northern countries to produce and ship supplies to endemic areas. With the new goal of eliminating onchocerciasis by 2030, and in view of the procurement challenges, there is an urgent need to develop and make available to endemic countries new diagnostic tools that are easy to use in the field with minimum procurement need, to enable rapid decision-making by NTD programs. Benin, like many other onchocerciasis-endemic countries, has therefore been selected to test two new diagnostic kits: the DDTD multi-antigen rapid diagnostic test (RDT) and Global Access Diagnostics (GADx) Oncho test (both are RDTs).
These diagnostic kits were tested under field conditions in three endemic districts with onchocerciasis prevalence ≤2% in order to assess feasibility and ease of use at point of care (POC), as well as performance relative to the existing SD Bioline OV16 RDT.
The target of this assessment was the community members living in onchocerciasis-endemic districts aged 5 and above. A total of 948 people, of which 53.59% were women, were sampled in the districts of Tchaourou, Bassila and Save..
o Overall positive onchocerciasis prevalence levels detected were 0.74%, 2.00% and 2.11% respectively for GADx, DDTD and SD Bioline. Only four samples were positive across all three diagnostics tests.
o No invalid test was recorded with the SD Bioline which was carried out in laboratory conditions, against three invalid tests for DDTD and two invalid tests for GADx, both of which were carried out in the field.
o In term of acceptability, both DDTD and GADx were found easy to use, although a few improvements are necessary before large scale use.
o For DDTD, technicians recommended reducing the reading time, while for GADx, it is crucial to change the buffer container lid to avoid spillage of the whole container and to improve the blood transfer device.