Intestinal shed appears as strands of orange tissue. Blood in the poop appears ruby red and is often a clot, not strands of tissue. But not all strains of coccdia results in bloody stools.
Chickens raised from chicks on local soil become resistant to coccida in that soil. But if you import soil or sand or borrow garden implements with soil attached from another locale, then there is a higher danger of your chickens becoming sick from those foreign coccidia.
Heavy rain with warm temps can cause such an explosion of coccidia that it can overwhelm the chickens defenses. Always be watchful for signs of lethargy and diarrhea, and be ready to start the flock on a coccidostat.