Giardia Infection (Giardiasis)

What is giardiasis?

Giardiasis is an infection of the intestine caused by a parasite called Giardia. This infection can spread easily to others.

What is the cause?

You may get infected from:

• food or water that has had contact with human or animal waste
• contact with things, like bathroom fixtures or towels, that have been touched by someone who is infected with Giardia
• being at a day care center where there are children who are infected and who are in diapers or not toilet-trained
• by anal-oral sex with someone who is infected

Drinking water from a stream or lake while camping or hiking is a common way to get infected with Giardia.

People most likely to have giardiasis are:

• travelers
• people who spend a lot of time outdoors, for example, camping
• children and their caretakers in day care centers
• people who have oral-anal sex

What are the symptoms?

Symptoms usually start 1 to 2 weeks after exposure to the parasite. Symptoms may include:

• mild to severe diarrhea
• bowel movements that are bulky, greasy, frothy, and foul smelling
• stomach cramps
• loss of appetite
• nausea or vomiting
• weight loss

Symptoms of giardiasis may last 2 to 6 weeks. Sometimes they last longer. Some people with giardiasis don’t have any symptoms.

How is it diagnosed?

Your healthcare provider will ask about your symptoms, examine you, and test a sample of bowel movement. Test results are usually back in 2 or 3 days.

How is it treated?

Your healthcare provider may prescribe an antibiotic. Take all of the medicine as prescribed. If you stop taking the medicine when your symptoms are gone but before the parasite is gone from your body, the infection may come back.

You may not need an antibiotic if you are not having symptoms. However, antibiotic treatment can help prevent spread to others. Talk to your healthcare provider about your situation.

How can I take care of myself?

If you have diarrhea, you may want to let your bowel rest for a few hours by not eating any food. Large amounts of watery diarrhea can cause dehydration, so it’s important to replace the fluids you are losing. Do this by drinking clear liquids, such as water, weak tea, bouillon, apple juice, or sports drinks or other oral rehydrating solutions. You may also drink soft drinks without caffeine (such as 7 UP). Let sodas lose some of their carbonation (go flat) before you drink them. Make sure you drink often. Not getting enough fluids to replace the fluids your body is losing while you are sick can be very dangerous. This is especially true for children, older adults, and some people who have other medical problems. Suck on ice chips or Popsicles if you feel too nauseated to drink fluids.

It is OK to keep eating as long as it does not seem to make diarrhea or stomach cramps get worse. Foods that are easiest to digest are soft, plain foods, such as bananas, cooked cereal, rice, plain noodles, gelatin, soft-boiled eggs, toast or bread with jelly, and applesauce. Go back to your normal diet after 2 or 3 days, but avoid milk products and caffeine for a few more days. For several days also avoid fresh fruit (other than bananas), alcohol, greasy or fatty foods, highly seasoned or spicy foods, and most fresh vegetables. Cooked carrots, potatoes, and squash are OK. If eating seems to make the diarrhea worse, go back to just clear liquids for a few hours. Then again try small amounts of the foods that are easy to digest.

If you have cramps or stomach pain, it may help to put a hot water bottle or electric heating pad on your stomach. Cover the hot water bottle with a towel or set the heating pad at low so you don’t burn your skin.

Be cautious about taking antidiarrheal medicines. Nonprescription medicines such as loperamide (sold as Imodium and other trade names) or the prescription medicine Lomotil can make you sicker, especially if the diarrhea is bloody. If you take one of these medicines, make sure you use only the dose recommended on the package. If you have chronic health problems, always check with your healthcare provider before you use any medicine for diarrhea.

If you keep having symptoms, your symptoms get worse, or you have new symptoms, tell your healthcare provider.

How can I help prevent giardiasis?

• Wash your hands well with soap and water after going to the bathroom and before eating or handling food.
• Wash your hands often, especially after you change diapers or help children use the toilet.
• Avoid unclean water supplies, including ice cubes made from water that may be unclean. When you travel to other countries with unsafe sanitation, avoid foods that are not cooked or peeled.
• Avoid food that may have been touched by dirty hands.
• Always wash diapers separately from other laundry.
• Tell others who may have been exposed to the parasite (such as household members, sex partners, and day care contacts). They may need to be tested for the parasite.*
• Avoid exposure to a partner’s anus, rectum, or bowel movements during sexual activity.
• Don't swim in public places while you have diarrhea.
• Protect food from contact with dirty hands, bowel movements, flies, and unclean water.
• When you are outdoors, particularly when camping or hiking, drink water only after it has been purified with boiling, proper filtration, or disinfectant tablets.