Pathogen, Symptoms, and Prevention and Control Methods of Louping Ill

This is a viral disease that causes inflammation of the brain, hence it is also called encephalitis. The disease occurs mainly in sheep and can occasionally cause illness in goats. It occurs only in mountainous areas with many ticks.

1. Pathogen

The pathogen is a flavivirus. The vector is the tick. Ticks infected with the virus can transmit the disease by biting healthy sheep. It can occasionally be transmitted to humans and shepherd dogs. In humans, it manifests as high fever and acute muscle pain, but it does not cause death.

2. Symptoms

Sheep: The incubation period is 1 to 3 weeks. After the virus enters the bloodstream, it causes high fever; the sick sheep becomes listless, has difficulty breathing, loses its appetite, and its body temperature reaches 40 to 41°C. After a few days the temperature drops and the condition improves. But after 1 week, typical neurological symptoms appear; the sick sheep becomes highly excited and begins to tremble, which is why it is also called trembling disease, with trembling of the head and neck being the most obvious. At this stage the body temperature rises again.

As the disease progresses, jumping begins to appear; at times it moves like a trotting horse, at times it lunges and jumps forward, and it lies down and kicks its legs, finally progressing to convulsions and paralysis.

Goats: Although no clinical cases have been reported, investigations of Scottish wild goats have proven that many goats have antibodies to this disease, indicating that goats may have experienced this disease.

3. Prevention

(1) The key is to control the harm caused by sheep ticks, carry out regular medicated baths, and burn and thoroughly cut the grass on pastures with severe tick activity; the preventive effect is obvious.

(2) Inject sheep in areas with many ticks with louping ill vaccine, once in early spring and once in late summer.

4. Treatment

There is no good treatment. Within 48 hours after contact with the virus, injection of antiserum may be expected to provide protection; once the body temperature rises, the use of antiserum is ineffective. If paralysis of the hind limbs has not occurred, giving large amounts of sedatives may be expected to cure it. However, it may become a virus carrier.