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

The research investigated Hendra virus (HeV) infections in 11 horses in New South Wales, Australia between 2006 and 2012, revealing that the disease was usually acute and resulted in death within 48 hours. Caution is advised when interpreting a negative diagnosis based solely on swab samples.

Research Methods and Findings

• The research was conducted on nine independent premises in New South Wales, where 11 cases of Hendra virus (HeV) infections in horses were diagnosed between 2006 and 2012. A premise was identified as a case if at least one horse was confirmed as infected with HeV by PCR.
• All reported cases were from the north-eastern region of NSW. Notably, 8 out of the 9 cases occurred within a span of two months in the winter of 2011.
• The researchers observed that horses impacted by the virus were kept at pastures on properties frequented by flying foxes. This suggests a possible correlation between the presence of these bats and the transmission of the virus.
• The study also found a significant association with fences; out of the 11 HeV-positive horses, 5 were found dead or dying on a fence line. The reason for this association was not provided, but further investigation may be insightful.

Clinical Symptoms

• The majority of horses exhibited an acute illness, which led to death within 48 hours. The predominant observed symptoms were neurological.
• Interestingly, there was limited transmission of the virus to horses in close contact, with only two premises having more than one horse affected.

Veterinarians’ Roles and Diagnostical Implications

• The research found significant differences in the sampling strategies employed by veterinarians. It was not specified what these differences were, but this variation may affect the reliability and consistency of test results.
• The researchers concluded that caution should be taken when interpreting a negative disease diagnosis when only swab samples have been collected. As the virus seems to manifest predominantly neurologically and acutely fatal, relying solely on swab samples for diagnosis may result in missed or false negative diagnoses.