Giardia (also called giardiasis or Giardia infection) is an infection of the small intestine caused by a microscopic parasite called Giardia lamblia. It is a common gastrointestinal parasite and it is estimated to cause over 300 million cases of giardiasis each year.
Mild symptoms of Giardia may not require any treatment, and mild infections may go away on their own within a few weeks.
Medications used to treat Giardia include:
- Metronidazole (Flagyl)
- Furazolidone (Furoxone, Dependal-M) for children younger than 5 years of age
Other treatment for Giardia includes:
- Fluid and electrolyte replacement because diarrhea can cause dehydration and salt imbalance
- Avoiding dairy and other products with lactose, which may trigger symptoms
Avoid swimming in pools, hot tubs, lakes, rivers, and the ocean until one week after completing treatment for Giardia, because patients who still have diarrhea can contaminate the water and make other people sick. Anal sex should also be avoided until treatment is finished.
What Are Symptoms of Giardia?
Symptoms of Giardia (giardiasis) include:
What Causes Giardia?
Giardiasis is caused by the Giardia parasite that lives in soil, food, water, and on surfaces that have come into contact with human or animal waste.
Giardia infections spread in three main ways:
- Waterborne transmission
- The most common route of infection
- Drinking from contaminated streams, reservoirs, or wells
- Using contaminated water used to prepare drinks or wash raw foods
- Commonly occurs among campers and hikers who drink from untreated water sources (rivers, streams, lakes) and people who travel to areas where inadequate water sanitation standards do not eliminate the organism
- Foodborne transmission
- The Giardia parasite is killed by cooking
- Uncooked food or food contaminated after cooking can cause infection
- Person-to-person transmission
- Occurs when traces of infected feces travel between two people
- Not thoroughly washing hands after using the bathroom or after changing the diaper of an infected child
- Person-to-person transmission is the cause of outbreaks in families and institutions, such as daycare centers and nursing homes
- Can also occur from anal sex
Almost all mammals can be infected with Giardia, and animal-to-person transmission can also occur.
How Is Giardia Diagnosed?
Giardia infection (giardiasis) is diagnosed with a patient history and physical examination. The diagnosis is confirmed by checking stool samples for the parasite. More than one stool sample may be needed.
Additional tests, such as endoscopy, may be indicated in some cases.
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