Influenza virus transmission from horses to dogs, Australia.

This study evaluates a 2007 incident in Australia where dogs in close contact with horses infected with influenza virus (H3N8) also contracted the disease. The researchers discovered that the virus’s genetic sequence in dogs was identical to that from horses, suggesting a direct transmission. However, they found no evidence of the virus transferring between dogs or persisting in dogs.

Introduction and Background

• The equine influenza outbreak in 2007 in Australia had an unexpected consequence – the apparent transmission of the virus from horses to dogs. This was a novel discovery, which raised questions about interspecies transferability of the influenza virus, particularly the H3N8 strain.

Research Findings

• Dogs in close contact with infected horses appeared to contract the respiratory disease. This suggested direct transmission from horses to dogs.
• Researchers confirmed this transmission by comparing the nucleotide sequence (the genetic makeup) of the virus found in dogs with those in horses.
• The identical genetic sequence between the virus in horses and dogs indicated that the influenza strain had not mutated when moving from the horse to the dog, confirming that the virus had indeed jumped species without any genetic changes.

Limitations and Conclusions

• Despite this confirmation of interspecies transmission, the study did not identify any evidence of dog-to-dog transmission.
• Moreover, there did not appear to be any persistence of the virus in dogs over time.
• This suggests that this interspecies transmission event might be rare and not have a significant impact on overall influenza spread or dog health.
• However, it highlights the potential for such transmission to occur, which may be significant in specific outbreak scenarios and requires more attention in disease surveillance and control efforts.