Unusual Neurological Signs Reported in Australian HorsesBy Press Release · April 27, 2011
Biosecurity officials are continuing to receive reports of horses showing unusual neurological signs in South Australia, Victoria and New South Wales. The neurological signs include ataxia (wobbly in the legs and difficulty walking) muscle tremors, and sensitivity to touch. These reports have decreased in the past week, which officials say may be a result of less mosquito activity due to the cooler weather.
Since the middle of February a total of 71 neurological cases in horses have been reported to Biosecurity SA by private veterinarians. Five of these horses have been euthanized while the rest are recovering from their illness. These reported neurological cases are spread across the state from the Riverland, down the length of the Murray, and in areas both north and south of Adelaide from Port Pirie to Victor Harbor.
Horses are being tested for a range of mosquito-borne viruses including Ross River virus and a group of viruses called “flaviviruses.” These include Kunjin virus and Murray Valley encephalitis virus. Maps showing the geographical distribution of these cases and their test results can be found on the Biosecurity SA Animal Health Website.
To gain further understanding about the flaviviruses that may be the cause of the neurological disease, Biosecurity SA is focusing its investigations and laboratory testing on horses that have significant clinical signs.
There is no known risk to humans from direct contact with horses infected with mosquito-transmitted viruses. However, a bite from an infected mosquito can spread some viruses to humans. A fact sheet about Murray Valley encephalitis in humans can be found on the Department of Health website.
Owners can attempt to protect their horses from mosquitoes by using repellents, covering them up, keeping them indoors at times of high mosquito activity (dawn and dusk) and minimizing possible mosquito breeding areas. Horse owners should contact their local veterinarian if their horse is unwell or behaving strangely.