Bluetongue Virus (BTV)

More suspected cases of Bluetongue Virus (BTV) have recently been detected in Northern Ireland, raising concerns about the spread of this vector-borne animal disease affecting livestock.

About Bluetongue Virus

The Bluetongue Virus (BTV) is responsible for causing bluetongue disease (BT), a severe haemorrhagic disease of ruminant animals.
It is an infectious but non-contagious disease, meaning it does not spread directly from animal to animal.

Bluetongue primarily affects domestic ruminants, including sheep, cattle, and goats, and can also infect wild ruminants such as buffalo, deer, antelope, and camels. Among domestic animals, sheep are the most severely affected.

BTV is found on all continents except Antarctica, indicating its wide geographical distribution.

Mode of Transmission

Bluetongue Virus is mainly transmitted through the bite of infected Culicoides midges, which are tiny blood-feeding insects commonly found on farms.

In some cases, certain strains of BTV can be transmitted vertically, from an infected mother to her fetus during pregnancy.

Human Health and Food Safety

Bluetongue Virus does not infect humans.
There are no food safety concerns, and meat and dairy products from infected animals are safe for human consumption.

Clinical Signs of Bluetongue Disease

Clinical symptoms are most commonly seen in sheep and occasionally in deer. The disease can be fatal in severe cases.

Key clinical signs include:

• High fever ranging from 40°C to 42°C

• Swelling of the lips, tongue, and head

• Nasal discharge

• Lameness

• Reddening around the coronary band (top of the hoof)

In some animals, the tongue may appear swollen and bluish in colour, which gives the disease its name. However, this sign is not always present and should not be solely relied upon for diagnosis.

Impact on Livestock and Economy

Bluetongue disease can result in high morbidity and mortality rates in flocks and herds.
It adversely affects livestock productivity, including reduced milk yields, and can disrupt domestic and international trade due to movement restrictions.

Treatment and Prevention

There is no effective treatment for bluetongue disease. Management is mainly supportive and focused on vector control.

However, vaccines are available for certain strains of BTV and are used in Africa, Asia, and parts of Europe to control the disease.