Equine viral encephalomyelitis

It is characterised by paralysis and other neurological signs. It mainly affects horses and other equidae, But other animals can be also affected. These include cattle, sheep and goats, pigs, birds (including poultry), dogs and rodents. Humans can also be affected.

EVE can be caused by several equine encephalomyelitis viruses, including:

• Japanese encephalitis
• Western equine encephalomyelitis virus
• Eastern equine encephalomyelitis virus
• Venezuelan equine encephalomyelitis virus
• West Nile virus

There has never been an outbreak of equine viral encephalomyelitis in the UK. But it remains a risk due to international animal movements.

Equine viral encephalomyelitis is a notifiable disease.

If you suspect the disease, you must report it immediately. Call the Animal and Plant Health Agency (APHA) Wales on 0300 303 8268.

Failure to do so is an offence.

Clinical signs of EVE can vary depending on:

• which virus the animal is infected with, and 
• the stage of infection

In severe cases, it can be fatal, however, some animals may not show any clinical signs at all.

Initial stages of infection may include:

• fever
• lack of appetite
• depression  
• stiffness of weakness

 Later stages of infection may include:

• behavioural changes - such as circling, head pressing or aimless wandering
• hyperexcitability
• blindness
• lack of coordination and balance
• inability to move
• staggering or standing with an open stance
• seizures

EVE viruses are usually spread through the bite of infected mosquitoes. Animals can also carry the virus from one location to another.

The disease is not spread directly from horse to horse. 

Only some types of mosquito can spread the virus. This means that if an infected horse did enter the UK, the possibility of the disease spreading would be low.

If you are bitten by an infected mosquito, you could be infected with equine encephalitis viruses. Most people have no symptoms.

An infected person or horse cannot pass the virus directly to others.

You should contact your GP for advice, if:

• your animal displays signs of infection, and 
• you are worried about your health

If you import animals, you must follow import rules (on gov.uk) to make sure they are free from disease and fit to travel.

You can help prevent the disease by:

• being familiar with the clinical signs of equine viral encephalomyelitis
• following good biosecurity practices

The Infectious Diseases of Horses Order 1987 (on legislation.gov.uk) includes the control of equine viral encephalomyelitis.