Pretty Parasites with Dr. Pritt, Part 3: “Beaver Fever” Creature Feature

Parasites can be pretty: pretty cute, pretty awesome, and sometimes pretty creepy. This article is part one of a five-part series featuring some of Dr. Bobbi Pritt's "freaky favorites," ranked from 1 (not too scary) to 5 (bad-news bugs).

Freaky factor 3/5: This critter comes from poop and can last a few weeks. But it’s easy to prevent with hand washing and good hygiene.

3-D artist rendering of a Giardia parasite.

Once upon a time, a group of hikers were out in the wilderness, and they decided to drink water from a stream. Little did they know that the water was polluted with beaver poop containing Giardia parasites. The hikers all got diarrhea, and they nicknamed the illness “beaver fever.”

Microscopic view of Giardia parasites.

Giardia can live in the guts of many mammals—not just beavers and humans. They’re microscopic and found all over the world. Giardia can survive outside the body, covered in a hard shell, for months. Once inside a person’s body, the shell dissolves, and the parasites are released. People usually get Giardia from contaminated food or water or from person-to-person contact. The good news is it’s easy to prevent:

  • Wash your hands after using the toilet and before and after eating or preparing food.
  • Drink only purified water. No matter how clean that mountain stream looks, don’t drink it without boiling it first.
  • If you travel to a place where you’re not sure the water is safe, drink and brush your teeth with bottled water. Also, don’t use ice, and avoid raw fruits and vegetables.

People with Giardia infections usually get better on their own in a few weeks. But if the symptoms are really severe or if a person is sick for a long time, a health care provider can prescribe medicine to help.

Bobbi Pritt, M.D., is a pathologist and microbiologist at Mayo Clinic. She loves learning about parasites. You can read her blog, Creepy Dreadful Wonderful Parasites and follow @ParasiteGal.

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