Hi, please read the highlighted link on my profile.
MG one of those blessed Mycoplamsa's are common and hatcheries are not tested for it as there are no laws.
Usually you do not see any signs in your flock until stress from weather, home change and illness or even broody, yes, I had a broody hen succumb to it, and only because I used to many treatments of antibiotics and she was immune to the types I use, such as terramycin.
Do not treat, unless you see a secondary infection such as wheezing, labored breathing.
As with any bird, 30 day quarentine is the safest, most practical way of the possibility of the new ones you bought needing to be culled then your whole flock.
Basic biosecurity, please find it in your search and read up.
If you take birds to the fairs or shows, please quarentine them again or keep them in show "Pens" away from the general population.
Personally, the Maine State Vet and Lab Tech say that MG is here in Maine, if you do get "clean" and tested birds, be very cautious as they can contract these mycoplasmas from wild birds that pass through. It does not mean you must cull your entire flock. You do have to be upfront with folks, most people have had a chicken with a "cold" and they live happily as long as you watch them.
Good luck!
PS- Terramycin does still work, but avoid any use of any medications unless you have a secondary infection!!! Have them tested. Generally what I've seen is that when everyone says they do not have it, they have not tested their flock for the mycoplasmas, these can be swabbed by the state your in, also NPIP can also be swab tested.
