Clinical and epidemiological features of West Nile virus equine encephalitis in New South Wales, Australia, 2011.

This research centers around an outbreak of West Nile virus (WNV) in horses in New South Wales, Australia, in 2011. It explores the clinical features, diagnoses and outcomes, highlighting the severity of the disease outbreak, and raises concerns about the potential for future outbreaks.

Study Overview

• The study scrutinizes a major outbreak of neurological disease in horses that occurred in NSW, Australia, between February and June 2011.
• The researchers identified the viral strain responsible for the majority of cases as West Nile virus originating from Australia. It was highly pathogenic.
• The main method of study involved reviewing clinical descriptions made by veterinary practitioners and corresponding laboratory reports connected to the outbreak.

Clinical Observations

• The range of clinical signs in affected horses varied. However, ataxia, a lack of voluntary coordination of muscle movements, was consistently observed in cases confirmed in the laboratory.
• West Nile virus was detected in brain samples using a real-time reverse transcription PCR assay and virus isolation technique. This provided a clear diagnosis of the disease.
• The study showed that an equine IgM ELISA, a diagnostic test for detecting West Nile Virus antibodies in horses, was the most effective way of confirming the WNV diagnosis.

Conclusions and Implications

• After the outbreak, a state-wide serological survey, a diagnostic test of blood serum, was carried out. The results indicated that, contrary to previous expectations, although the infection had been widespread, the overall prevalence of antibodies to the West Nile Virus was very low. This means a significant proportion of horses had not been exposed to the virus before and were thus susceptible to infection.
• These findings suggest that there may be a considerable risk of future West Nile virus outbreaks, given the low antibody presence in the equine population. The horse population is hence deemed vulnerable to future disease attacks.