The common ones are Mericks and Cocci.
I don't vaccine mine for mericks and in many small flocks it is not reccomended. However, Mericks is not an issue in this area so another reason I have no plans in vaccinating them. It is known to be an effective vaccine though.
As for cocci. It is in all soils. With slow exposure to the protozoa in the soil, they will gain an immunity to it naturally in the first few months of life. They thrive in wet soil, so keep the runs dryer and should be fine. Cocci vaccine was developed for the organic market that says no drugs can be used. Amprol and Sulmet are often used to treat infestations of this protozoa, with amrprol being a thamine blocker that inhibits the growth of the protozoa, does not stop it from infecting the bird, thus if the conditions are bad and lots are in the soil, they can still get sick from it.
Worming, is another thing you don't have to do. If you are dead set on worming them, take a fecal sample to the vet. They can tell you what kinds of worms they have if they have any, as not all wormers work on the same types of worms. Furthermore, worming is hard on the intestines, and so the less you treat, and not treating when not necessary is better. I've had birds for 10+ years and have never wormed any of them. Just plain not necessary and birds do just fine.
I peronsally think less is more. Let them play out in the dirt and build up their own immunities to the local bugs and stuff you have in your yard. Every flock has their own balance of bactera and microorganisms, and will develop a strong resistance to it, and gain a natural balance.
Good luck!
