Nairobi Sheep Disease: An arbovirus infection of sheep and goats transmitted by ticks. It is characterized by high fever and hemorrhagic gastroenteritis.Nairobi sheep disease virus: A species of NAIROVIRUS, transmitted by the ixodid ticks and producing a lethal gastroenteritis in sheep and goats. Though a major veterinary pathogen, its effect on humans has not been firmly established.Nairovirus: A genus of the family BUNYAVIRIDAE named after NAIROBI SHEEP DISEASE, an acute, hemorrhagic, tick-borne, gastroenteritis affecting sheep and goats. The type species is Dugbe virus. Some viruses in this genus are capable of causing severe and fatal disease in humans.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Sheep: Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.Sheep Diseases: Diseases of domestic and mountain sheep of the genus Ovis.Sheep, Domestic: A species of sheep, Ovis aries, descended from Near Eastern wild forms, especially mouflon.