Tick Borne Viruses

Abstract

Nairobi sheep disease virus (NSDV) is a one of the viruses transmitted by tick vectors and causes Nairobi sheep disease (NSD) – a disease of small ruminants. The disease was first identified as a problem in sheep and goats in Kenya in 1910. The virus belongs to the genus Nairovirus and family Bunyaviridae. An equally pathogenic variant of NSDV is Ganjam virus, which is found in India and Sri Lanka. Both viruses are closely related to the human pathogen Crimean-Congo haemorrhagic fever virus (CCHFV), a fever transmitted through infected tick bites or through contact with infected animal blood or tissues during and immediately after slaughter. Other members of the genus include Dugbe virus, Hazara virus, and Kupe virus, isolated from cattle ticks in East Africa. The virus is spread by hard (Ixodid) ticks and appears to be dependent on the tick vector for dissemination, with no direct transmission between animals. The transmission of tick-borne viruses (TBV) occurs primarily during tick feeding and is a complex process, known to be promoted by tick saliva constituents.