Lassa fever diagnostics: past, present, and future

Abstract

Lassa fever is a unique viral hemorrhagic fever that is endemic in parts of West Africa, primarily Sierra Leone, Guinea, Liberia, and Nigeria. The disease is caused by the Lassa virus, an Old World arenavirus that has as primary reservoir host the multimammate rodent Mastomys nataliensis, which lives in association with humans. Recent estimates suggest LF causes two million cases and 5000-10000 deaths annually, mainly in West Africa. Clinical diagnosis and laboratory confirmation have always been major challenges for effective management and control of the disease in afflicted areas of West Africa. Recent advancements in molecular biology, recombinant DNA technology, and genomics sequencing has facilitated major advancement in development of better diagnostic and surveillance tools for Lassa fever virus. These include, the multiplex, magnetic bead-based immunodiagnostics for both Lassa virus antigens and antibodies; molecular probe-based quantitative real-time PCR for genomic signatures; rapid diagnostics tests that detects the most prevalent West African lineages; and the successful utilization of next-generation sequencing technology to diagnose and characterize Lassa virus in West Africa. These advances will continue to improve disease treatment, control, and prevention. In this review we will discuss progression of Lassa virus diagnostics from the past and into the future.

Figure 1.

Lassa fever lineage distribution across Nigeria. Next generation sequencing of Lassa virus revealed that the virus lineages in Nigeria are separated geographically by major natural boundaries, which are the rivers Niger and Benue. Lineage III is found in the north (green colour) and separated from lineage IIB (Orange colour) in the South East and South-South by river Benue, and lineage IIA (Purple colour) in the South West by River Niger. The numbers in the graph represent number of successful complete Lassa virus sequences performed at each of the localities.