Our puppy picked up coccidia earlier this summer (probably from the rain water thaat stayed and stayed at our park). Once we got her on anti-biotics, the diarrhea cleared up within a few days, completely by the end of a week. Of course, she is much easier to give pills to than cats are. If you have trouble try getting some pill pockets. They are expensive, but some cats will just gobble them down, including the pill.
Dr. Seuss~DLH (brother's cat)~June 2007-
Misty~DSH (my cat & Mooby's mom)-?-
MooBoots(Mooby) ~ DMH(Mom's cat)~July 21, 2008-
Sunshine~ Golden retriever X white german sheperd (Dad's dog)~October 24, 2008-