At least 20 people central Oklahoma have a contagious diarrheal disease but health officials haven't determined what the source is yet.

Shari Kinney with the Cleveland and McClain county health departments says 17 cases of Cryptosporidiosis are confirmed in Cleveland County and three more were verified in McClain County.

The disease is caused by a parasite called Cryptosporidium and can cause severe and long-lasting diarrhea.

The parasite is commonly found in swimming pools, splash pads and day care centers and is transmitted through the fecal matter of an infected person.

Norman Recreation Director Jud Foster says water samples from the splash pad at Andrews Park tested positive for the parasite. However only one-third of the people who became ill visited the splash pad.