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). It 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. 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. Giardia transmission can occur by accidentally swallowing the parasite; a person cannot become infected through contact with blood.
When a person becomes infected, the parasite begins to multiply within the intestines. After one to two weeks, symptoms of Giardia can occur.
Common symptoms include:
- Diarrhea
- Gas or flatulence
- Greasy stools that tend to float
- Bloating
- Belching
- Stomach cramps
- Vomiting
- Abdominal (stomach) 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 to treat an infection
(see Giardia Medication). These medicines cure the infection in about 80 percent of people. If a person's symptoms do not improve with treatment, the healthcare provider may recommend another medication or the same medicine for a longer time. Treatment of infections also involves staying well hydrated and possibly treating people with whom the infected person has been in contact.
Anyone can get a Giardia infection. However, people who are 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 the parasite
.
How to Prevent a Giardia Infection
People can do several things to prevent 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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