There is evidence suggesting that NRIV stems from a naturally occurring reassortment event in which a host was infected with both BUNV and BATV.

[1] It is commonly found in areas that experience an outbreak of Rift Valley fever virus (RVFV)[2] The primary form of transmission of the virus to humans is through mosquitos.

[5] The virus has been reported primarily in African countries which include Mauritania, Senegal, Sudan, Central African Republic, DRC, Kenya, Somalia, South Africa, and Madagascar.

[3] Humans that are infected by the virus typically develop severe or fatal hemorrhagic fever.

[1] Ngari virus was first isolated in Senegal in 1979 from Aedes simpsoni mosquitos.