Nairobi Sheep Disease Virus, an Important Tick-Borne Pathogen of Sheep and Goats in Africa, Is Also Present in Asia

Nairobi sheep disease (NSD) virus is the prototype of the tick-borne NSD serogroup, genus Nairovirus, family Bunyaviridae. It is highly pathogenic for sheep and goats, causes disease in humans, and is widespread throughout East Africa. Ganjam virus has caused disease in goats and humans in India. Due to their occurrence on different continents and association with different ticks, these viruses were considered distinct despite serologic cross-reactivity. Their S RNA genome segments and encoded nucleocapsid proteins were found to be 1590 nucleotides and 482 amino acids in length and differed by only 10 and 3% at nucleotide and amino acid levels, respectively. Genetic and serologic data demonstrate that Ganjam virus is an Asian variant of NSD virus. These viruses were phylogenetically more closely related to Hazara virus than Dugbe virus.