Giardiasis Fact Sheet

A microscopic parasite found in soil, water and food contaminated by feces of infected animals or humans causes giardiasis. People who swallow the parasite can develop diarrhea for several days. The infection is treatable with medications.

Incidence

• According to the U.S. Food and Drug Administration (FDA), as of 2009, giardiasis is the most common cause of nonbacterial diarrhea in North America. The U.S. Centers for Disease Control and Prevention (CDC) states that about 20,000 cases were reported in the United States each year between 2003 and 2005.

Risk Factors

• Risk groups include travelers to world regions where hygiene is not stringent, hikers and campers who drink contaminated stream or spring water, people who swim in public pools, children in day-care centers, and men who have sex with men.

Symptoms

• Symptoms of giardiasis include diarrhea for more than 10 days, abdominal pain, bloating, gas, nausea and weight loss. The CDC notes that not all infected people have symptoms.

Complications

• According to the CDC, giardiasis is associated with the development of reactive arthritis, an inflammatory autoimmune response to infection. This condition usually is temporary.

Treatment

• Treatment involves antibiotics, most commonly metronidazole (Flagyl) for adults and furazolidone (Furoxone) for children. Some people recover without medication, and the CDC assumes that a number of people with giardiasis symptoms do not seek treatment.