Giardiasis, an illness that affects the digestive tract (stomach and intestines), is caused by a microscopic parasite called Giardia lamblia. The parasite attaches itself to the lining of the small intestines in humans, where it interferes with the body's absorption of fats and carbohydrates from digested foods.

Giardia is one of the chief causes of diarrhea in the United States, and spreads through contaminated water. It can survive the normal amounts of chlorine used to purify community water supplies, and can live for more than 2 months in cold water. As few as 10 of the microscopic parasites in a glass of water can cause a severe case of giardiasis in a human being who drinks it.

Young kids are more likely to have giardiasis than adults, so some experts think that our bodies gradually develop some form of immunity to the parasite as we get older. But it isn't unusual for an entire family to have giardiasis, with some family members having diarrhea, some just crampy abdominal pains, and others with few or no symptoms.

Signs and Symptoms

Between 1% and 20% of the U.S. population has giardiasis, and this number may be 20% or higher in developing countries, where giardiasis is a major cause of epidemic childhood diarrhea. More than two thirds of people who are infected may have no signs or symptoms of illness, even though the parasite is living in their intestines.

When the parasite does cause symptoms, the illness usually begins with severe watery diarrhea, without blood or mucus. Giardiasis affects the body's ability to absorb fats from the diet, so the diarrhea contains unabsorbed fats. That means that the diarrhea floats, is shiny, and smells very bad.

Other symptoms include:

• abdominal cramps
• large amounts of intestinal gas
• an enlarged belly from the gas
• loss of appetite
• nausea and vomiting
• sometimes a low-grade fever

These symptoms may last for 5 to 7 days or longer. If they last longer, a child may lose weight or show other signs of poor nutrition.

Sometimes, after acute (or short-term) symptoms of giardiasis pass, the disease begins a chronic (or more prolonged) phase. Symptoms of chronic giardiasis include:

• periods of intestinal gas
• abdominal pain in the area above the navel (belly button)
• poorly formed, "mushy" bowel movements (poop)

Prevention

Here are some ways to protect your family from giardiasis:

• Drink only from water supplies that have been approved by local health authorities.
• Bring your own water when you go camping or hiking, instead of drinking from sources like mountain streams.
• Wash raw fruits and vegetables well before you eat them.
• Wash your hands well before you cook food for yourself or for your family.
• Encourage your kids to wash their hands after every trip to the bathroom and especially before eating. If someone in your family has giardiasis, wash your hands often as you care for him or her.
• Have your kids wash their hands well after handling anything in "touch tanks" in aquariums, a potential source of giardiasis.
• Have your water checked on a regular basis if it comes from a well.

Also, it's questionable whether infants and toddlers still in diapers should be sharing public pools. They certainly should not if they're having diarrhea or loose stools (poop).

Media Contact:

Allison Grey
Journal Manager
Journal of Infectious Diseases and Diagnosis
Email: jidd@microbialjournals.com