Evaluation of the diagnostic accuracy of the ReLASV Pan-Lassa Antigen Rapid Test for Lassa Fever in Nigeria

Lassa fever is a zoonotic disease found in several countries across West Africa, with estimates of up to 300,000 infections and 10,000 deaths yearly. The highest incidence is in Nigeria. Suspected cases are often seen in areas with limited infrastructure and diagnostics capacity, hence the availability of an accurate rapid diagnostic test (RDT) that could be used in the community would be an important public health tool. Unfortunately, few RDTs for Lassa fever exist and have not been thoroughly validated. Toward that end, we conducted a Phase 2 performance evaluation to assess the diagnostic accuracy of the ReLASV Pan-Lassa Antigen Rapid Test (Zalgen Labs, Frederick, MD, USA) using archived, frozen whole blood, plasma, and serum samples collected from individuals in Nigeria to determine its suitability for widespread use as a screening tool for Lassa fever. The overall performance of this RDT was measured against the reference test, the Altona RealStar LASV real-time reverse transcription polymerase chain reaction 2.0 (Altona Diagnostics, Hamburg, Germany). The sensitivity and specificity of the ReLASV Pan-Lassa Antigen Test were 65% and 50.7%, respectively. The low diagnostic accuracy indicated in our and other independent evaluations of the ReLASV Pan-Lassa Antigen Rapid Test suggests that this test, at least until further developed, refined, and validated, is not suitable for making critical diagnostic or treatment decisions for Lassa fever, at least for lineages that commonly circulate in Nigeria. These findings underscore the importance of thoroughly assessing the performance characteristics of tests to ensure their reliability and accuracy.