Another horse has died from Hendra virus on the New South Wales mid-north coast. The horse was on a property at Dondingalong near Kempsey when it became seriously ill on Monday and failed to respond to antibiotics.
The 13-year-old quarter horse died on Tuesday and tests have confirmed it was infected with Hendra virus.
The state's Acting Chief Veterinarian, Dr Therese Wright, says she does not believe the death is directly linked to three other horse deaths at Kempsey and Macksville in the past month.
"I don't believe that they are linked by any human or animal movement," she said.
"We believe that they're probably all a result of contact with flying foxes that have been in flowering or fruiting trees on the properties."
Dr Wright says vaccination is the best prevention.
"Vaccination is the single most effective way of preventing your horse from getting the Hendra virus," she said.
"You should also try and keep your horse out of paddocks with flowering or fruiting trees, and if your horse is sick it's really important that you protect yourself."
The Department of Primary Industries says a second horse on the property is being quarantined.
The local public health unit is assessing the risk to people who came into contact with the infected horse.
Authorities say Hendra vaccination rates remain low and they are calling on all horse owners to have their animals immunised.
NSW Health Director of Communicable Diseases Dr Vicky Sheppeard says people who have contact with sick horses should take precautions.
"Horse blood, nose and lung secretions and urine can all carry the virus and put people who come in contact with them at risk," she said in a statement.
"Human treatments for Hendra remain experimental, so avoidance of exposure to the virus is the safest course of action."