Caused by a microscopic parasite, giardiasis is a common intestinal infection in the United States. The parasite, Giardia intestinalis, thrives on surfaces and in the soil, food, or water contaminated with the feces of infected animals and humans. Protected by an outer coating, the parasite can survive outside the body and in the environment for a long time, even months. Giardiasis can be contracted by accidentally swallowing the parasite but not by contact with blood. The CDC estimates at least 2.5 million cases of giardiasis each year.
Travelers to developing countries where this parasite is prevalent have the highest risk of developing giardiasis. Giardia is spread by drinking water or using ice cubes made from contaminated sources. Eating uncooked food contaminated with the parasite can cause this infection. Giardiasis is prevalent among hikers and campers who can be exposed to contaminated water sources and have limited resources for good hygiene. People who swim in recreational public pools, water parks, and hot tubs can accidentally swallow water contaminated by a infected person. Changing tables, diaper pails, toys, and bathroom fixture are sources of contamination especially for children in daycare. Poorly monitored or improperly maintained wells are a source of contamination to unsuspecting individuals.Certain sexual practices place individuals at risk for infection.
The symptoms of giardiasis generally begin one to two weeks after becoming infected. The most common symptom is diarrhea lasting more than 10 days. Symptoms vary among individuals and are dependent how many organisms were ingested, the duration of the infection and the individual's overall health. Other symptoms are flatulence, abdominal cramping, nausea, and greasy stools that float. Dehydration and weight loss can result. In otherwise healthy individuals, the symptoms can last for 2 to 6 weeks. In some cases, the symptoms can last longer.
Diagnosis is made by checking for the parasite in a sample or sometimes multiple samples of a patient’s stool. A physician will prescribe medication to treat the infection although some cases resolve without intervention.