» Update: Death toll 7 at Waikato Farm
New Zealand has recorded its first confirmed cases of the neurological form of equine herpes virus 1 (EHV-1).
The country’s Ministry for Primary Industries said the cases were on a stud farm. It has not disclosed the location at this time, but it is understood to be in the North Island. Later reports indicate that 12 horses have been infected, of which six have been euthanised. All other horses on the property are being closely observed.
EHV-1 is a common virus in New Zealand and many horses are infected as foals, normally showing no clinical signs of disease.
The virus often sits dormant and can be reactivated later in life. Reactivation is more likely in times of stress, such as, giving birth, weaning and long distance transport.
The neurological form, known as myeloencephalopathy, has been known to occur in North America, Europe and Australia. It often results in the euthanising of the infect animal, once it is unable to stand.
The ministry said it was confident all affected horses were contained and the situation was under control.
It said no other properties had been affected.
It stressed that EHV-1 cannot be transmitted to people or other animals, and does not pose a risk to human health.
The ministry urged horse owners to be vigilant for signs of disease and to contact their veterinarian if concerned, saying several exotic diseases can also cause neurological signs in horses.
The ministry, along with the New Zealand Equine Health Association and the New Zealand Veterinary Association, were monitoring the situation closely and providing information to horse owners and veterinarians.
Signs of the neurological form of EHV-1 include fever, decreased co-ordination, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy, and an inability to rise.
The incubation period for the disease may be as little as 24 hours and up to 12 days, but is typically 4-6 days.
In countries where the disease is present, neurological cases tend to occur in older horses. It is rare in horses under 3 years of age.
Larger breeds are more commonly affected than ponies and smaller breeds.
Mares are more commonly affected than geldings or stallions.
Giving birth, weaning, mixing, transportation and concurrent infections are all stress factors that may trigger neurological outbreaks.
It is spread by direct horse-to-horse contact or by contaminated hands and equipment.
Horses may appear to be perfectly healthy yet spread the virus via the secretions from their nostrils.
The ministry stressed that it can also be spread indirectly through contact with physical objects, such as tack, contaminated with infectious virus.
Veterinarians who suspect the disease are likely to perform a nasal swab or blood test.
A case of EHV-1 virus often presents no symptoms at all, but may trigger respiratory disease of varying severity, abortion and neonatal death. The most severe cases take the neurological form
Standard care is primarily supportive. Treatments may include intravenous fluids or anti-inflammatory drugs. Antibiotics may be used to treat a secondary bacterial infection if one develops; however, antibiotics have no effect on EHV-1 itself.
Vaccines for EHV-1 are only protective against the respiratory and abortive forms of EHV-1. Vaccines do not provide protection against the neurological form.
The growing number of cases of the neurological form in recent years in the United States have seen scientists working overtime to find a vaccine and medications that will improve survival rates.
Outbreaks are costly for the horse industry. Quarantines and tracing efforts funded by authorities to prevent its spread amount to millions of dollars annually in the United States. Events are cancelled to reduce the risk of spread and dozens of competition horses end up confined to their stalls or properties.
On top of that, nearly a third of horses that contract the neurological form die or are euthanized.
Scientists are still piecing together the puzzle around a potentially fatal virus that is little different from the standard EHV-1 strain that usually causes little more than a cold.