I'm so sorry for your loss. It sounds like you're doing a great job with the surviving puppies. You might want to continue treating the adults and all other animals in the house as well. Adults can have the organism and not be sick. This condition is very contagious and if you don't treat the adults they will continue to give it to the puppies. Regardless of what you may hear, this is a serious condition in puppies and can be life threatening as you unfortunately already know.
Here is an excerpt from:
http://www.peteducation.com/article.cfm?articleid=727
A puppy is not born with the coccidia organisms in his intestine. However, once born, the puppy is frequently exposed to his mother's feces, and if the mother is shedding the infective cysts in her feces, then the young animals will likely ingest them and coccidia will develop within their intestines. Since young puppies, usually those less than six months of age, have no immunity to coccidia, the organisms reproduce in great numbers and parasitize the young animal's intestines. Oftentimes, this has severe effects.
From exposure to the coccidia in feces to the onset of the illness is about 13 days. Most puppies who are ill from coccidia are, therefore, two weeks of age and older. Although most infections are the result of spread from the mother, this is not always the case. Any infected puppy or kitten is contagious to other puppies or kittens. In breeding facilities, shelters, animal hospitals, etc., it is wise to isolate those infected from those that are not.