Giardiasis, an illness that affects the digestive tract, is caused by a microscopic parasite called Giardia lamblia. The parasite attaches itself to the lining of the small intestines in humans, where it sabotages 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 is transmitted 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 three times more likely to have giardiasis than adults, which leads some experts to believe that our bodies gradually develop some form of immunity to the parasite as we grow 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
It's estimated that between 1% and 20% of the U.S. population has giardiasis, and this figure may be 20% or higher in developing countries, where giardiasis is a major cause of epidemic childhood diarrhea. But 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.
