I have 22 hens that are now 5 months old (4 different breeds -- Rhode Island Red, White Leghorn, Black Minorca and Cuckoo Moran) and have recently noticed the brown warty lesions on the combs of 5 or 6 of them, mostly the Leghorns. Mosquitoes haven't been a big problem. They don't seem to be terribly affected by it, still eating and the leghorns have even started laying in the past week. Should I vaccinate everyone or just let it run it's course? Any suggestions on what I can do to keep their immune systems strong while they muddle through it? And how long can I expect this to last?