HENDRA – A timely reminder
AUTHOR: Megan Scott (Senior Veterinary Officer - Acting) Emergency Animal Preparedness, CVO Unit; DEDJTR
Spring Racing carnival has recently ended and with the current Queensland inquiry into Hendra vaccination, it is a good time to remind ourselves of the risks and actions to take when dealing with a suspect case of Hendra.
First identified in 1994 in Queensland, there have since been detections in both Queensland and northern NSW. There have been no confirmed clinical cases in Victoria.
Regardless, the risk should not be ignored as we see the movement of horses into Victoria from high-risk areas on a regular basis and if one of these animals was incubating the virus we could very easily see our first case.
Hendra disease is a Notifiable Disease and any suspected cases must be reported to Agriculture Victoria on the Emergency Animal Disease hotline 1800 675 888 or to your local District Veterinary Officer.
What is Hendra disease?
Hendra is a sporadic viral disease of horses (and rarely humans) caused by a Henipavirus.
Pteropid bats (Flying foxes) are the natural reservoir of the virus and do not seem to develop clinical disease. Recent research suggests that one of the highest transmission risks is contact with bat urine when horses feed or water in areas frequented by flying foxes. Black flying foxes and Spectacled flying foxes have demonstrated the highest levels of virus excretion in urine and other body fluids. Both of these species are not present in the wild in Victoria. Despite this, there is still evidence in our local flying fox populations, (such as grey-headed flying foxes) of exposure and seroconversion to the virus.
Hendra virus (HeV) is a serious zoonotic disease and of the seven human cases diagnosed, four have died. The common risk factor in these cases has been close occupational contact with horses that at the time were not known to be infected with HeV. All bodily secretions (e.g. naso-pharyngeal secretions, blood and urine) and tissues are potentially infectious.
Direct transmission from bat-to-humans, human-to-human, or other species-to-human has not been recorded. Experimental studies have demonstrated dogs may contract the virus, most likely from infected horses, without exhibiting any overt clinical signs and could also pose a transmission risk.
What are the clinical signs of Hendra in horses?
Typically HeV infection causes an acute illness that is rapidly fatal BUT some cases have shown variable and sometimes vague clinical signs which complicate an early diagnosis. Signs have included fever, increased heart rate, difficulty breathing, weakness and neurological signs such as an uncoordinated gait. The incubation period in natural infections has ranged from 5-16 days.
There are no pathognomonic signs for HeV infection.
How can I manage the risks?
There are a number of ways that you can protect yourself, your staff and your clients from contracting HeV when dealing with potentially infected horses;
Wear Personal Protective Equipment (PPE) – everyone handling the horse should be protected
- Protective overalls, gloves and rubber boots
- P2 facemask – a basic surgical mask is NOT suitable
- Protective eyewear
- Avoid invasive procedures – dental work, nasogastric tubing, necropsy and other high-risk procedures should be avoided until the animal has been cleared of any HeV infection. Even basic injections can pose a risk.
- Vaccination – an effective vaccine is now on the market and readily available from vaccine suppliers.
Prepare yourself, prepare your clinic and prepare your clients because the consequences of HeV infection can be serious. Purchase the necessary PPE (and use it!), add the hotline to your phone (1800 675 888) and contact your local Agriculture Victoria staff if you have any questions.
Further information is available at:
- Hendra virus
- Guidelines for veterinarians handling potential Hendra virus infection in horses
- AVA Guidelines for veterinary personal biosecurity