Watery diarrhea is a primary symptom of crypto, along with abdominal pain, nausea, vomiting, cramping of the lower abdomen, weight loss, loss of appetite, dehydration, and passing gas (flatulence).
Most cases of crypto can be diagnosed using a stool sample. To do so, the stool is stained with a dye and examined under a microscope. Another way to diagnose crypto is by endoscopy or colonoscopy. These procedures use thin, long cameras inserted down the throat or through the anus to examine the small (and large) intestine. Samples of intestinal tissue are collected and examined in a lab.