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updated: 9/12/2011 11:56 AM

Hand washing key to avoiding nasty GI parasite

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It was not, the teen thought, a really great way to spend a week of her summer vacation.

At least she wasn't throwing up, but all the other unpleasant GI symptoms were there.

After attempting to eat, the girl experienced stomach cramps, upper belly pain and stinky diarrhea. Her pediatrician ordered a stool work-up, and within a few days, results showed that the culprit was not a bacterium or a virus but the parasite, giardia.

In their 2010 Pediatrics in Review article, Dr. Sabah Kalyoussef and colleagues explain that the organism giardia intestinalis infects the small intestine, and is the No. 1 cause of protozoan diarrhea in the world. In fact, in developing countries almost all children have already been infected with giardia by the age of 2.

Giardiasis also affects approximately 20,000 Americans each year. Typical victims include hikers who drink water contaminated with the waste of infected animals, as well as kids younger than 5 who pick up the organism by the fecal-oral route, courtesy of infected child care classmates.

Kalyoussef reports that most individuals infected with giardia will not show any outward signs of disease. Children who are symptomatic usually become ill within one to 14 days of exposure. Acute giardiasis generally lasts one to three weeks and results in watery diarrhea, cramping, nausea, vomiting, weight loss and gassiness. Because it causes malabsorption of essential nutrients, chronic giardial infection can also lead to failure to thrive in more vulnerable children.

Experts at the American Academy of Pediatrics do not recommend treating asymptomatic giardia carriers. Children with symptoms of giardiasis can be treated with one of three available anti-parasitic drugs of choice -- tinidazole, metronidazole or nitazoxanide -- which have fairly high cure rates ranging from 80 percent to 100 percent.

The U.S. Department of Agriculture suggests taking several steps to avoid infection by the microscopic one-celled giardia parasite. As always, parents and kids need to do a good job at hand washing before preparing foods and eating, as well as after using the restroom, changing diapers or handling animals. Gardeners should not use untreated manure to fertilize fruit and vegetable plants, and raw produce should always be washed, peeled or cooked before consuming.

Children with giardia should not swim in public pools until they have been symptom-free for two weeks. Other swimmers should remember it's always wise to avoid swallowing water while swimming. Hikers and campers unable to access treated municipal water supplies while traveling are advised to drink bottled water or to boil natural sources of water for one minute to kill the giardia parasite.

• Dr. Helen Minciotti is a mother of five and a pediatrician with a practice in Schaumburg. She formerly chaired the Department of Pediatrics at Northwest Community Hospital in Arlington Heights.