Les Sims wrote:

All H5N1 viruses isolated in Eurasia since 1996, whether from ducks geese or chickens are already highly pathogenic for chickens. They do not need passage in chickens to change to a highly pathogenic form.


Les Sims

Yes, I understand that point, yet the virus had not been particularly pathogenic for other species (not many others) until it became such an issue for Chickens. Those chickens that are asymptomatic/immune may well be adding some mystery point mutation necessary to be virulent to more of the wild bird species.

Otherwise, with (an) H5N1 (variant) in chickens for so many years, wouldn’t we have seen a lot more die off in wild birds as we are seeing now?

Slightly less fatal disease in chickens allows more transport of asymptomatic, or less ill chickens(chicks??). Slightly more fatal virus shows up as higher epidemic exposure in wild populations. Vaccination with sub-optimal vaccine may amplify the carrier-syndrome in domestic poultry.

(Maybe I’m stretching it a bit here, but sci-fi speculation is a hobby of mine.)