Mild infections of giardiasis parasites may clear up on their own in a few weeks. However, more severe cases of giardia may cause long-term symptoms and complications.
Giardiasis is an intestinal infection caused by the parasite, Giardia duodenalis. Although it is more common in areas with poor hygiene and unclean water, the parasite is found globally. Children and adults who live in unhygienic areas or people who practice anal sex are at a higher risk of contracting the parasite.
Infection from giardiasis is typically associated with stomach cramps, bloating, nausea and watery diarrhea. While infection symptoms may go away on their own in a few weeks, intestinal problems may remain long after recovery.
Long-term complications of the giardiasis parasite may include:
What are the signs and symptoms of giardiasis?
Though people infected with giardiasis may not always present signs or symptoms, they can still carry and spread the parasite through their stool. When signs and symptoms do develop, they usually appear one to three weeks after exposure and may last two to six weeks, but they can last longer or recur.
Common signs and symptoms of giardiasis include:
How does giardiasis spread?
Infection occurs when the parasite cysts are accidentally swallowed by drinking contaminated water and eating contaminated food. The infection can spread through person-to-person contact (through touching contaminated feces while changing a child’s diapers, during sexual contact, etc.) or by transferring the infection from the hands to the mouth after touching contaminated surfaces, such as doorknobs.
How is giardiasis diagnosed?
To diagnose giardiasis, the doctor must perform a complete clinical assessment. Stool samples are tested in the laboratory, and, for better accuracy, the doctor may advise you to submit several samples collected over different days. Stool tests may also be done to monitor the effectiveness of treatment.
How is giardiasis treated?
Children and adults without symptoms of giardiasis usually don’t need treatment unless they are likely to spread the parasites. Supportive treatment with fluids may be given to prevent dehydration. Those with mild symptoms may recover without treatment in a few weeks.
For those with severe signs and symptoms, doctors may prescribe an antibiotic, such as metronidazole, tinidazole and nitazoxanide (liquid form and easier for children to swallow). The doctor may also prescribe medication to reduce the intensity of symptoms.
What are the complications of giardiasis?
Giardiasis is usually not fatal, especially in developed countries. However, even after the infection clears up, there can be long-term symptoms and the infection can recur, leading to serious complications. Infants and children are at a higher risk of complications.
Some of the most common complications of giardiasis include:
- Dehydration: due to severe diarrhea.
- Failure to thrive: chronic diarrhea can result in malnutrition and affect a child’s physical and mental development.
- Lactose intolerance: many people with giardiasis develop lactose intolerance (inability to digest milk sugar properly), which can persist for a long time after the infection clears up.
Complications can be prevented by seeking timely treatment from a doctor (especially in kids), drinking plenty of fluids and eating a healthy diet.
How can giardiasis be prevented?
There is no medication or vaccine to prevent giardiasis, though some precautions can be taken to prevent giardiasis, which includes:
- Proper hand hygiene
- Drinking clean water (bottled water or boiling water for at least 10 minutes at 158°F can kill the parasite cysts)
- Washing vegetables and other produce properly
- Avoiding opening the mouth while swimming in pools, lakes or streams
- Practicing safer sex
Medically Reviewed on 7/28/2021
Centers for Disease Control and Prevention. Parasites – Giardia. https://www.cdc.gov/parasites/giardia/index.html