The Most Common Parasites that Can Affect Humans

4. Crypto

This parasite causes a diarrheal illness by the same name when ingested, usually from infected water. Like giardia, crypto has a protective shell that gives it a measure of longevity outside of the body. It usually doesn't cause serious illness in people with healthy immune systems, although it is one of the leading water-borne contaminants in the United States. In immunocompromised people, however, crypto can cause more severe problems. Most people recover on their own the with help of fluids.