Giardia is a one-celled microscopic parasite. This parasite is also known as
Giardia intestinalis or
Giardia lamblia. Giardia is the cause of the diarrheal illness
giardiasis.
Giardia is the most common nonbacterial cause of
diarrhea in the United States
(see Diarrhea Causes).
Giardia is also one of the most common intestinal parasites worldwide, infecting up to 20 percent of the world's population.
Giardia is most prevalent in developing countries where infections are associated with poor sanitary conditions.
Giardia infections are more common in children than in adults. However, chronic infections are more common in adults.
Giardia is found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. Transmission can occur by accidentally swallowing the parasite; a person cannot become infected through with Giardia through contact with blood.
When a person becomes infected with Giardia, the parasite begins to multiply within the intestines. After one to two weeks, symptoms of Giardia can occur.
Common Giardia symptoms include:
- Diarrhea
- Gas or flatulence
- Greasy stools that tend to float
- Bloating
- Belching
- Stomach cramps
- Vomiting
- Abdominal pain
- Upset stomach or nausea.
These symptoms may lead to weight loss and dehydration.
In order to make a Giardia diagnosis, the doctor will likely:
- Ask a number of questions
- Perform a physical exam
- Recommend certain tests.
As part of testing for Giardia, your healthcare provider will probably ask you to submit stool samples. Because the parasite can be difficult to diagnose, you may have to submit multiple stool specimens over several days.
Treating Giardia Infections
Several prescription medicines are available for
Giardia treatment
(see Giardia Medication). These medicines cure
Giardia infection in about 80 percent of people. If a person's symptoms do not improve with treatment, the doctor may recommend another medication or the same medicine for a longer period of time. Treatment of
Giardia infections also involves staying well hydrated and possibly treating close contacts.
Who Is at Risk for a Giardia Infection?
Anyone can get a Giardia infection. Persons more likely to become infected include:
- Childcare workers
- Parents of infected children
- International travelers
- People who drink from shallow wells
- People who swallow water from contaminated sources
- Children who attend daycare centers, including diaper-aged children
- Swimmers who swallow water while swimming in lakes, rivers, ponds, and streams
- Backpackers, hikers, and campers who drink unfiltered, untreated water.
Contaminated water includes water that has not been boiled, filtered, or disinfected with chemicals. Several community-wide outbreaks of giardiasis have been linked to drinking municipal water or recreational water contaminated with Giardia.
How to Prevent a Giardia Infection
People can do several things to prevent an infection with Giardia. Some of these include:
- Practicing good hygiene
- Avoiding food and water that might be contaminated
- Avoiding fecal exposure during sexual activity.
Giardia lamblia was initially named Cercomonas intestinalis by Lambl in 1859, and was renamed Giardia lamblia by Stiles in 1915, in honor of Professor A. Giard of Paris and Dr. F. Lambl of Prague; however, many people consider Giardia intestinalis to be the correct name for this parasite.
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