A parasite that is species specific means specific to birds (waterfowl, guineas, chickens), canine (dog, wolf, coyote), rodent (mouse, rat), rumen animal(cow, sheep, goat) and so on. Even humans have a human strain of cocci which affects them! So chickens being a bird can get it from other birds because birds are a species classification, but not all strains of cocci will affect each individual type of animal within a species classification the same. Strain A may affect all, while strain B may affect only affect one type. Human forms can be picked up and shared among other humans and primates. So since there are cocci types for birds, your chickens can get it from turkies, wild birds, and so on, however, you dog cannot get the cocci chickens have from eating chicken poop and vice versa. However, just because it is species specific, does not mean it cannot travel in a non host species, it just means that it cannot complete it's life cycle (replicate) in other hosts. So a dog can carry chicken type of coccidiosis, but it cannot replicate, however can be spread through it's feces into new soil, from which a host species must consume it for it to replicate. Does that make sense?
Why then is the first attempt to diagnose the cause of diarrhea on this board almost always coccidiosis?
Well, because it is so common and:
coccidiosis is the most over-discussed and over-worried-about chicken disease there ever was among owners of backyard flocks.
It is so common that it is often what is afflicting birds. Unlike other parasites like worms, mites, and lice, which can also be carried in by wild animals, with lice being species specific(birds to birds, mammals to mammals), they often have a longer life cycle and the effects on birds are often so minimal people don't notice till it is really bad. Lice and worms can kill a chicken, but it often takes weeks and a really bad infestation, while cocci can kill in days because the life cycle is very fast.
A potential reason that cocci is a "bigger deal" in many urban chicken homes is because 1) Feeds are now available without the meds which was "normal" at one point for all feeds to have it. 2) Chicks are often brooded inside without early exposure thus making them more prone. 3) People tend to panic over normal things like the first pile of cecal poo from their chicks thinking they are sick, and when posting that their chick has a "brown runny poop" , people tend to panic and expect the worst.
Furthermore, this is a very diverse board with first time raisers, and long time raisers; people who do it the "old way" and people who do it "the new way"; people who have backgrounds in many fields, it is easy to pick up info from many sources and have it spread and interpreted differently here and there. From a bioengineering/cell and molecular biology background, I can run across articles on the subject and be able to make heads and tails of what is trying to be said, if I were to pick up a physics journal, I'd be totally lost and more apt to picking up hear say.
So we are all here to learn together and often it is up to the end user to take information and advice on an open board to their own discretion.
To me, cocci is just one of those things to deal with and know it exists. If you know it exists, just be prepared and it doesn't have to be devastating.
People fuss over not feeding this and that to their birds, but mine go though the scrap pile, compost bins, full of "do not feed" items like potato peels, tomato plants and so on.
Plus, it's that season for cocci scares. Every year topics like bad chick shipments, when can they go outside, cocci/sick chicks, is this a rooster, when will my hens lay, are they too cold, is this frost bite repeats again and again.
