Giardia infection (giardiasis)
Giardia infection (giardiasis)
Giardia infection is an intestinal infection marked by abdominal cramps, bloating, nausea and bouts of watery diarrhea. Giardia infection is caused by a microscopic parasite that is found worldwide, especially in areas with poor sanitation and unsafe water.
Giardia infection (giardiasis) is one of the most common causes of waterborne disease in the United States. The parasites are found in backcountry streams and lakes, but also in municipal water supplies, swimming pools, whirlpool spas and wells. Giardia infection can be transmitted through food and person-to-person contact.
Giardia infections usually clear up within six weeks. But you may have intestinal problems long after the parasites are gone. Several drugs are generally effective against giardia parasites, but not everyone responds to them. Prevention is your best defense.
Some people with giardia infection never develop signs or symptoms but still carry the parasite and can spread it to others through their stool. For those who do get sick, signs and symptoms usually appear one to two weeks after exposure and may include:
Signs and symptoms of giardia infection usually improve in two to six weeks, but in some people they last longer or recur.
When to see a doctor
Giardia parasites live in the intestines of people and animals. Before the microscopic parasites are passed in stool, they become encased within hard shells called cysts, which allows them to survive outside the intestines for months. Once inside a host, the cysts dissolve and the parasites are released.
Infection occurs when you accidentally ingest the parasites. This can occur by swallowing contaminated water, by eating contaminated food, or through person-to-person contact.
Swallowing contaminated water
Giardia parasites are found in lakes, ponds, rivers and streams worldwide, as well as in municipal water supplies, wells, cisterns, swimming pools, water parks and spas. Ground and surface water can become contaminated from agricultural runoff, wastewater discharge or animal feces. Children in diapers and people with diarrhea may accidentally contaminate pools and spas.
Eating contaminated food
The giardia parasite is a very common intestinal parasite. Although anyone can pick up giardia parasites, some people are especially at risk:
Giardia infection is almost never fatal in industrialized countries, but it can cause lingering symptoms and serious complications, especially in infants and children under age 5. The most common complications include:
Preparing for your appointment
While you may initially bring your symptoms to the attention of your family doctor, he or she may refer you to a gastroenterologist — a doctor who specializes in disorders of the digestive system.
What you can do
What to expect from your doctor
Tests and diagnosis
To help diagnose giardiasis, your doctor is likely to test a sample of your stool. For accuracy, you may be asked to submit several samples collected over a period of days. The samples are then examined in a laboratory for the presence of parasites. Stool tests may also be used to monitor the effectiveness of any treatment you receive.
Treatments and drugs
Children and adults who have giardia infection but no symptoms usually don't need treatment unless they're likely to spread the parasites. Many people who do have problems often get better on their own in a few weeks.
When signs and symptoms are severe or the infection persists, doctors usually treat giardiasis with medications such as:
No drug can prevent giardia infection. But common-sense precautions can go a long way toward reducing the chances that you'll become infected or spread the infection to others.
Last Updated: 2010-05-29
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