So I've had chickens for all of 4 months and have recruited some lovely birds with the idea of breeding a few (two colours of Orpington), a few eggs to eat and sell and also to take advantage of this naturally broody breed to sit on duck and goose eggs. I lost one hen to a dog, then a smaller hen (possibly cockerel - was always a bit suspicious) just died. I didn't get him/her checked out because he/she wasn't a huge loss to my breeding plans. But then the first of my beautiful breeding cockerels got sick, followed shortly by the other. I got the vet involved quickly on them but even after throwing lots of meds at them, they both died. PM inconclusive, tests sent off (at great expense) showed Avian Leukosis. Now I've got another hen sick (i.e. going to die shortly, I'm just too soft to finish her off). The vet has already said I should have a closed flock for six months - no chicks although the ducks and geese are fine to breed from. Oh, and three of these sick chickens are from one breeder who I've contacted and has had no problems so they have all contracted it horizontally from the first chicken to die i.e. this is certainly pretty contagious. My stats are definitely not good - not an egg to be seen in all this time but a fortune spent on setting it all up, driving all over the place to collect the chickens and the price for them plus vet bills galore.
So my question - what would you do? I think I have a few options:
1) Just hang on with them and see which ones survive. After six months I'll know that any that are left are immune but they may be carriers so I'll never know whether new birds would be affected. They can still lay and brood waterfowl eggs for me but my breeding plans would be screwed.
2) Hang onto them for next season with the sole intent of brooding waterfowl eggs but then cull late summer with the idea of leaving a few months clear before recruiting fresh stock next autumn.
3) Culling now, buying an incubator, heat lamp etc.etc. so I can hatch ducks, geese and chickens of my own next season.
I know 3) seems like the most logical option (especially if you already incubate eggs - all seems a bit intimidating to me) but the eight birds I have left are all lovely and seem in the picture of health (even the one remaining cockerel who is from the 'dodgy' breeder that sold me the first sick chicken). I just find it hard to contemplate - especially four new hens that I bought after I lost the first two but before I realised there was something contagious going round. Or is there another option? Do you know whether there is any sort of test to see whether they're carriers or not?
OK, rambling over. Help

Thanks!
Hester