Avoiding giardiasis

Download this Patient Note in PDF format

VOL 109 / NO 6 / JUNE 2001 / POSTGRADUATE MEDICINE

Diarrhea, abdominal cramps, bloating, and belching are sometimes caused by a parasite called Giardia (gee-AR-dee-ah). This tiny bug can easily find its way into the small intestine of animals (especially beavers and bears but also dogs, cats, and farm animals). The parasite can then be passed on to people, who may quickly share it with one another.

The number of cases of Giardia infection seems to be increasing in the United States. The parasite, which causes an illness called giardiasis (gee-ar-DYE-a-sis), forms into a cyst that can leave the body in feces (stool). Once outside the body, Giardia organisms live in water and die when dried out. Infection can occur after exposure to just a few organisms--maybe just one, according to some experts. Although symptoms are uncomfortable, giardiasis usually isn't dangerous.

Who is most likely to get giardiasis?
Some people pick up giardiasis from water or food that has been contaminated with the parasite. Others get it from direct contact with contaminated stool, such as when changing diapers or touching soiled clothing of an incontinent person or during other intimate contact with someone who has the infection.

Travelers are at risk throughout the world, and hikers and campers can easily get giardiasis if they drink water from streams or lakes, which may be contaminated no matter how clean the water appears. Other risk factors include:

• Exposure to a family member who has the infection
• Contact through day-care centers, nursing homes, hospitals, or other institutions
• Exposure through sexual or other intimate activity
• Spread through inadequate hand washing

How do you know if you have giardiasis?
Many people--perhaps as many as 60%--never have symptoms after exposure to Giardia organisms. The important thing to remember is that even when infection causes no symptoms, it can still be spread to others. The timing of symptoms can range from 3 to 25 days after exposure, but symptoms usually occur within 7 to 10 days. They often last just a few days, but sometimes they continue for weeks or months--even years. The most common symptoms are:

• Watery diarrhea with foul-smelling stool
• Bloating, stomach pain, cramps, belching, or gassiness
• Frequent bowel movements and intermittent diarrhea
• Nausea, vomiting, weight loss, and loss of appetite

How is giardiasis treated?
Many infections run their course and disappear on their own, but in some cases, drug treatment is needed. The drugs must be prescribed by a physician, who may also want to check a stool sample before and after treatment to make sure the parasite actually goes away. Drinking lots of fluids to replace nutrients lost through diarrhea is another important part of treatment. Infections that last a very long time are more common in adults than in children, and people who have immune disorders, such as AIDS, tend to have a more difficult time recovering from giardiasis. These people may need to try several kinds of treatment before they feel better.

How can you avoid this problem?
Never drink water directly from a stream or lake, and sterilize water that comes from any questionable source by boiling it for 5 minutes. If you are traveling in areas where water supplies may not be safe, drink bottled water or canned carbonated beverages that come sealed. Do not add ice.

Carefully dispose of sewage and diaper wastes so you do not contaminate surface water or groundwater that could spread illness to others. And, of course, wash your hands thoroughly if you come in contact with feces or soiled clothing and after you touch pets or other animals.

Don't forget to wash your hands

When done correctly, hand washing is the single most effective way to prevent spread of disease. Giardiasis and many other infections are passed on through a fecal-oral route. Because disease is spread through ingestion of even the tiniest bit of contaminated material, hand washing after using the toilet cannot be overemphasized.

Correct hand washing is more complicated than many people realize. These steps are important:

• Wet your hands with warm running water, when possible
• Add soap, then rub your hands together, making a soapy lather. Do this away from the running water for about 20 seconds so you don't wash the lather away. Be sure to lather the front and back of your hands and spaces between fingers and under nails.
• Rinse your hands well under warm running water. (Keep hands down so the water runs into the sink instead of down your arms.) Turn off the water with a paper towel and throw that towel away.
• Pat hands dry with a clean paper towel.

It's important to remind children to wash their hands before eating, after using the bathroom, after blowing their noses, and after playing outdoors or touching pets or other animals. Also, don't assume that children know how to wash their hands. (With toddlers, singing "Twinkle, Twinkle, Little Star" while they lather up helps them understand how long to scrub.) Also, wash your own hands as your children wash theirs. Teaching by example is an excellent way to help youngsters establish good hand-washing habits.

This information is not a substitute for medical treatment.

Please send technical questions related to the Web site to Ann Harste