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Bluetongue
Bluetongue is a viral disease that mainly affects sheep, but also cattle and goats. It is transmitted by small biting insects and causes inflammation of the mucous membranes and blood vessels. It represents a significant economic concern fo...
What is it?
Bluetongue is a viral disease that mainly affects sheep, but also cattle and goats. It is transmitted by small biting insects and causes inflammation of the mucous membranes and blood vessels. It represents a significant economic concern for livestock farming in Tunisia and worldwide.
The disease is caused by a virus called Bluetongue virus, belonging to the Reoviridae family. Several serotypes of this virus exist, which complicates animals' immune protection. The virus multiplies in the body of the infected animal and in certain insect vectors.
Areas where Culicoides midges thrive, particularly warm and humid regions, present an increased risk. Summer periods and farms located near stagnant water sources favor the presence of vector insects. Lack of herd vaccination is also an important risk factor.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
The most common signs in sheep are fever, swelling of the muzzle and lips, excessive salivation, and sometimes a bluish tongue. Lameness, weight loss, and breathing difficulties may also be observed. In cattle and goats, symptoms are often milder or absent.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Transmission
The virus is mainly transmitted through the bite of small midges called Culicoides, which act as biological vectors. The disease does not spread directly from one animal to another through simple contact. Transmission can also occur from mother to fetus in certain cases.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
If bluetongue is suspected, it is essential to contact a veterinarian promptly for proper examination. Only a professional can confirm the disease and guide appropriate care for the animal. Never attempt to administer treatment without veterinary advice.
Prevention
Herd vaccination remains the most effective prevention method when recommended by veterinary authorities. Controlling vector insects, such as using repellents and managing stagnant water sources, helps limit the spread. It is also advisable to avoid animal movements from areas where the disease is present.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 08 August 2026
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