Is Hendra Virus More Common Or More Commonly Diagnosed?
Another horse farm in Queensland is under quarantine for Hendra virus. This follows the high-profile outbreak on another Queensland farm this past summer that resulted in the death of a veterinarian. Ongoing identification of affected farms is quite concerning for a disease that is typically very rare and sporadic. It's hard to say what this means.
Does it mean that Hendra virus is spreading and becoming more common? It's certainly a possibility. Even though we've known about this virus for a while and it's only caused rare outbreaks until now, established infectious diseases sometimes change their patterns for no clear reason.
Does this mean that Hendra virus is just being recognized more now? This is certainly a possibility too. Not all apparent changes in disease patterns are truly changes in disease patterns. Improved awareness, diagnostic tests or increased efforts to diagnose a disease can all lead to the impression that a disease is becoming more common when in fact it's just the same. I don't know whether that's the case in Queensland, but Hendra is certainly getting a lot more attention now. I suspect that many horses that would not have been tested in the past are now being tested.
How do we answer these (and other) questions? Research and surveillance. We need to know a lot more about this virus. We need to make sure that horses with signs that might be indicative of Hendra virus get tested. Since veterinary medicine is a user-pay system and diagnostic testing often gets skipped (especially when a horse has already died), some form of subsidized testing might be required. Unfortunately, a lot of it comes down to money. Money is needed to do research, provide diagnostic testing, perform surveillance and educate everyone involved. Money for these types of efforts is getting harder to find, although it's usually much easier during a high-profile outbreak.
Image: Grey-headed Flying-fox (Pteropus poliocephalus) (source: www.environment.gov.au, photographer: Andrew Smith)
