bluetongue

Bluetongue is the term used for bluetongue disease, an infectious condition of ruminant animals caused by the bluetongue virus (BTV), a member of the Orbivirus genus in the Reoviridae family. The virus is primarily transmitted by biting midges of the genus Culicoides, which act as vectors that spread infection among susceptible livestock, especially during warm, humid conditions.

The disease primarily affects sheep, which can develop severe clinical signs, but cattle, goats, and wild ruminants may also be infected. Common clinical features include fever, oral mucosal ulcers, swelling of the face and lips, excessive salivation, nasal discharge, and edema of the tongue that can lead to a characteristic bluish discoloration (hence the name). Other signs can include lameness, respira­tory distress, abortion in pregnant animals, and, in some cases, high mortality. Many infections, however, are subclinical or produce mild signs, particularly in cattle.

Bluetongue is caused by multiple serotypes of BTV, with distribution and severity influenced by vector activity and climate. The virus circulates in the bloodstream and causes vascular damage, leading to edema and hemorrhages. Outbreaks have occurred in Africa, parts of Europe, Asia, and the Americas, with climate change and global trade affecting spread and vector ranges. Vaccination options exist, using inactivated or live attenuated vaccines, along with vector control and movement restrictions to prevent spread. Diagnosis relies on laboratory tests such as PCR for viral RNA, virus isolation, and serological assays to detect antibodies. Bluetongue is not considered a human zoonosis, and treatment is primarily supportive care for affected animals.