The toll in New Zealand’s first confirmed outbreak of the neurological form of equine herpes virus 1 (EHV-1) has risen to seven, New Zealand’s Ministry of Primary Industries (MPI) confirmed today.
The seven horses on a Waikato stud farm were euthanised after contracting the dangerous form of the virus.
Another six horses affected by the virus on the same farm are receiving care, but no new cases have been reported on the farm since Sunday, February 2.
Ministry spokesman Andre van Halderen said the virus had not been reported on any other properties, and the owner of the affected farm had voluntarily quarantined the five affected paddocks.
Biosecurity measures were in place on the farm, with disinfection footbaths and overboots for staff. The affected paddocks have not been entered since January 20, and those handling the sick horses are showering afterwards. No other routine procedures which involve the handling of horses on the farm have been undertaken.
“MPI and industry are satisfied the current quarantine measures in place are sufficient to manage the situation,” van Halderen said.
He said as EHV-1 had not been reported elsewhere in the country, no other properties had needed to implement quarantine measures.
Speculation on online forums had suggested an imported horse could be to blame for the virus, but van Halderen said that while the MPI was investigating the movement of horses on and off the property, the origin of the virus may never be known.
“[The virus] could have arrived relatively recently, or it may be that the disease was triggered in a horse that had been a latent carrier for a long time,” he said.
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 foaling, weaning and long distance transport.
Outbreaks of the neurological form of EHV-1, known as myeloencephalopathy, have occurred in North America, Europe and Australia, often with fatal results.
Van Halderen said diagnostic scientists were doing further testing to find out more about this strain of EHV-1.
Horses and equipment associated with animals or water being imported into New Zealand need to meet strict biosecurity conditions which are outlined in MPI’s Import Health Standards.
In addition, all incoming passengers must declare if they are carrying equipment used with animals, items that have been used outdoors, and if they have been in contact with animals (except domestic cats and dogs) and/or visited a farm in the previous 30 days.