As winter arrives in Australia, the Australian Veterinary Association (AVA) is reminding owners in that country to vaccinate horses to help prevent them from contracting the deadly Hendra virus.

Ben Poole, BVSc, MANZCVS, president of AVA’s equine group, said although Hendra virus—which has only been diagnosed in Australia thus far—can strike at any time, traditionally there are more cases during the cooler months.

“Hendra is a deadly virus,” he said. “For the benefit of horses and their owners, it is essential that horses located in, around or travelling to high-risk Hendra areas along the east coast, are vaccinated against Hendra virus.”

The virus was identified in 1994. Since then, 102 horses in Queensland and New South Wales have died due to the virus.

“Every one of these horses that has died because of Hendra represents one more compelling reason for horse owners to vaccinate their horses,” Poole said. “The risk this disease poses to human health is also very real with seven confirmed cases in people leading to four deaths. So, it’s important that the horse community remains vigilant in protecting both horses and people from Hendra.”

Poole said the vaccine, introduced in 2012, remains the most effective way to manage the Hendra virus and is fully registered with the Australian Pesticides and Veterinary Medicines Authority.

“Vaccination of horses provides a public health and workplace health and safety benefit by reducing the risk of Hendra virus transmission to humans and other susceptible animals and helps to ensure high standards of animal health and welfare,” he said.

Hendra virus has been known to yield numerous clinical signs in horses including lethargy, respiratory distress, frothy nasal discharge, elevated body temperature (above 40°C, or 104°F), and elevated heart rate; however, authorities caution that infection does not have specific signs.

The virus is transmitted to horses from flying foxes, a type of fruit bat that frequents Australia, but the exact method of transmission remains unclear.

The zoonotic disease is transmissible to humans and has killed four people since it was first discovered, including an equine veterinarian who contracted the virus after treating an affected foal in 2009.