GIARDIASIS - Watsons Health

GIARDIASIS

Giardia infection (giardiasis) is one of the most common causes of waterborne disease. 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 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.

Although anyone can pick up giardia parasites, some people are especially at risk:

  • Children. Giardia infection is far more common in children than it is in adults.
  • People without access to safe drinking water. Giardiasis is rampant wherever sanitation is inadequate or water isn’t safe to drink.
  • People who have anal sex. Having anal sex without using a condom puts you at increased risk of giardia infection, as well as sexually transmitted infections.

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 three weeks after exposure and may include:

  • Watery, sometimes foul-smelling diarrhea that may alternate with soft, greasy stools
  • Fatigue or malaise
  • Abdominal cramps and bloating
  • Gas or flatulence
  • Nausea
  • Weight loss

Signs and symptoms of giardia infection may last two to six weeks, but in some people they last longer or recur.

DIAGNOSIS

Your doctor will ask questions about your past health and will do a physical exam to find out if you have giardiasis. He or she may also test your stool for the parasite that causes the infection by:

  • Stool exam. The samples are examined in a laboratory for the presence of parasites. Stool tests may also be used to monitor the effectiveness of any treatment you receive. Despite requiring three samples of stool, microscopical examination of stool identifies other parasites in addition to Giardia that can cause diarrheal illness.
  • Antigen testing. The best single test for diagnosing giardiasis. For antigen testing, a small sample of stool is tested for the presence of Giardial proteins. The antigen test will identify more than 90% of people infected with Giardia.
  • String test. It is a more comfortable method for obtaining a sample of duodenal fluid. The collected duodenal fluid is expressed from the string and is examined under the microscope.

 

RECOMMENDED MEDICATIONS

Children and adults who have giardia infection without 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:

  • Metronidazole (Flagyl). Metronidazole is the most commonly used antibiotic for giardia infection. Side effects may include nausea and a metallic taste in the mouth. Don’t drink alcohol while taking this medication.
  • Tinidazole (Tindamax). Tinidazole works as well as metronidazole and has many of the same side effects, but it can be given in a single dose.
  • Nitazoxanide (Alinia). Because it comes in a liquid form, nitazoxanide may be easier for children to swallow. Side effects may include nausea, flatulence, yellow eyes and brightly colored yellow urine.

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