Rift valley fever: diagnostic challenges and investment needs for vaccine development

Rift valley fever virus (RVFV) is a causative agent of a viral zoonosis that constitutes a major clinical burden in wild and domestic ruminants. The virus causes major outbreaks in livestock (sheep, goats, cattle and camels) and can be transmitted to humans by contaminated animal products or via arthropod vectors. Human-to-human transmission has not been reported to date, but spill-over events from animals have led to outbreaks in humans in Africa and the Arabian Peninsula. Currently, there is no licensed human vaccine against RVFV and the virus is listed as a priority pathogen by the World Health Organisation (WHO) due to the high epidemic potential and the lack of effective countermeasures. Multiple large RVFV outbreaks have been reported since the virus was discovered. During the last two decades, over 4000 cases and similar to 1000 deaths have been reported. The lack of systematic surveillance to estimate the true burden and incidence of human RVF disease is a challenge for planning future vaccine efficacy evaluation. This creates a need for robust diagnostic methodologies that can be deployed in remote regions to aid case confirmation, assessment of seroprevalence as well as pathogen surveillance required for the different stages of vaccine evaluation. Here, we perform comprehensive landscaping of the available diagnostic solutions for detection of RVFV in humans. Based on the identified gaps in the currently available in-house and commercially available methods, we highlight the specific investment needs for diagnostics that are critical for accelerating the development of effective vaccines against RVFV.