Yes it can reoccur as it's a parasite; they can get reinfested with it. Like coccidia, the adults do develop some resistance to it, but not like say, you've had measles so you can't ever get it again. So if a bird accumulates a heavy infestation a second or third time, it can still have liver damage to the point that it dies. Think of it like an intestinal parasite rather than a bacterial or viral disease. If your turkeys are eating a lot of earthworms in an area where the parasites are present, you should follow a worming program like a horse owner would worm for intestinal parasites. So when it's muddy and there's a lot of earthworms coming to the surface where the poultry can get them, that's when you should worm. For me it's a couple of times a year in the spring and fall. Ivomec will keep the cecal worms from settling in for at least 10 days, it's not like you have to do this every day. On the other hand, once the blackhead organism is in the liver and causing yellow poop, you have to treat for it for 14 days straight per my local avian vet.
They get blackhead like this: the blackhead organism is a parasite of the cecal worm. The cecal worm is a parasite of earthworms. The turkey eats the earthworms when it's rainy and the earthworms come to the surface to keep from drowning. If you get rid of the cecal worms with a wormer, you'll never get to the point where your turkeys actually have the blackhead organisms in their livers.
Are you in the US? Both ronidazole and dimetridazole are readily available by internet mail order in pills sized for birds from pigeon supply businesses like Pigeon Supplies Plus. They have them in 30 mg. and 12.5 mg. tablets. Dosage is 12.5 mg per kg (2.2 lbs) bodyweight once a day for 14 days.
