Sick hen...

[Hilary B]

As you are not sure what they have, it's best to take every precaution, and most things can be harboured in the ground so if you treat the house and utensils and then leave litter in the run there is a chance you could still be infected. If they were confined to a run could you move it to a new area? if they free ranged then I would confine them, for a while.
Usually 30 days is a good guide to quarantine most infections, I know it seems a long time but it would be best to be safe.
This is why the unscrupulous should not be breeding birds ( I am not saying these people are by the way, as we can all have the odd bad day ) but there are people out there that have no idea and shouldn't be let loose on livestock.
Sorry I know I go on!! but it gets chicken keeping a bad name!

Yeah, and if there is any 'used litter' around, I'd recommend burning it if possible, composting may work if you are sure your compost-heap will get properly hot.

[Albanach]

I can move them to fresh ground, this is where they are penned in for most of the day (5m by 5m electric fence) but when I come home from work they currently free range in mine and the neighbours garden. This could mean they could have access to the area previously used by the sick birds.

Not sure about blowtorching the wooden chicken run or my landlords lawn...