CVO Bulletin

West Nile Virus
 

Recent testing at Elizabeth Macarthur Agricultural Institute (EMAI) has diagnosed West Nile virus – Kunjin strain (WNVKUN) in four foals in two distant parts of the state. Two foals showing severe neurological signs have recovered with appropriate supportive care. The other two are still undergoing treatment.

WNV is a mosquito borne virus belonging to the genus Flavivirus. A strain of WNV, WNVKUN is endemic in parts of Australia and has been present for many years. Only occasional cases are usually seen, however in 2011 there was a widespread outbreak across NSW involving approximately 300 horses.

Horses, people and a variety of other animals, especially birds, may become infected through a bite from an infected mosquito. Like most other arboviral infections the disease is expected to occur during late summer and autumn. A La Nina weather event such as NSW is experiencing during 2021-2022 increases the risk of infection due to a widespread increase in mosquito numbers.

The initial signs of disease in horses can be non-specific and may be mistaken for colic as horses appear depressed and reluctant to move, however these signs are soon followed by neurological signs. The most common signs include ataxia (including stumbling, staggering, wobbly gait, or incoordination) and hyperaesthesia but a range of other central nervous system (CNS) signs may also be observed.

For further information please read the CVO Bulletin.