Clinical review of Hendra virus infection in 11 horses in New South Wales, Australia.

CASE SERIES: Between 2006 and 2012, there were 11 horses diagnosed with Hendra virus (HeV) on 9 independent premises in New South Wales (NSW). We defined a case of HeV as premises where one or more horses were confirmed to be infected with HeV by PCR. All the cases occurred in the north-eastern region of NSW. In 8 of the 9 cases, infection occurred within 2 months over the winter of 2011. With no exception, the affected horses were kept at pasture on properties visited by flying foxes. Of the 11 horses testing positive for HeV, 5 had an association with a fence, with the horses dead or dying on a fence line. In the majority of cases, disease was an acute illness leading to death within 48 h. When signs of disease were observed, neurological signs predominated. There was limited spread to in-contact horses, with only two properties having more than one horse affected. There was significant variation in the sampling strategies undertaken by veterinarians.
CONCLUSION: Caution is needed to interpret a negative diagnosis when only swabs have been collected.