Can cryptosporidiosis be contagious?

Yes: It's highly contagious through contact with stool. Hand washing is very important.

Cryptosporidiosis: Cryptosporidiosis is infection w cryptosporidium parasites that embed in small intestine walls. The parasite is shed in feces. It can be picked up from water, food, soil or surfaces. If those parasites are ingested, then infection pursues. Dx: acid-staining test of stool or biopsied intestinal tissue & enzyme immunoassays for antigens.