What Is Giardiasis?
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Giardiasis - Causes, Symptoms, Diagnosis, and Treatment

Published on Sep 07, 2022 and last reviewed on Feb 20, 2023   -  4 min read


Giardiasis is an infection that affects the intestine caused by giardia, resulting in diarrhea, stomach cramps, and vomiting. Read the article below to know more.


Giardiasis is a waterborne disease found worldwide, especially in places with poor sanitation and contaminated water. Swallowing contaminated or recreational water from lakes, rivers, or pools is the most common cause of the disease.

What Is Giardiasis?

Giardiasis affects the small intestine and is a parasitic infection. Giardia is the causative organism of the disease and can spread through direct person-to-person contact or by consuming contaminated food and water. The infection is marked by diarrhea, stomach cramps, nausea, and vomiting.

What Is the Cause of Giardiasis and How Is It Spread?

Giardiasis is caused by a microscopic parasite that infects the intestine - giardia and is found in human and animal feces and can contaminate anything. Once the parasite enters a person’s body, it lives in the intestine and is passed in stools. However, giardia can live outside the body for an extended time, for weeks or months.

Giardiasis can be spread by:

What Are the Risk Factors?

Giardiasis is a common illness and can affect anybody; however, some are at a higher risk of contracting the disease.

  • Children are at the most risk of giardiasis, as they are likely to come in contact with feces, especially in a child care center.

  • Parents and caretakers who change diapers.

  • People who stay in places without access to safe drinking water: giardiasis spreads in places with poor sanitation and without access to safe water.

  • Travelers and backpackers travel to different places and may not have access to safe water and food.

  • People who engage in unprotected anal or oral-anal sex

What Are the Symptoms and Signs of Giardiasis?

The clinical symptoms in a person would depend on many factors, including the parasite load, the immune response of the person, etc. Some people may not show symptoms. Symptoms may appear one to two weeks after the infection and may last for two to six weeks. However, in people with weaker immunity, it may last longer.

The symptoms include:

  • Diarrhea.

  • Weakness.

  • Stomach cramps.

  • Headache.

  • Gas or flatulence.

  • Nausea and vomiting.

  • Greasy stools that float.

  • Anorexia (an eating disorder represented by abnormally low body weight).

  • Low-grade fever.

  • Weight loss.

  • Dehydration.

  • Itchy skin.

  • Swelling of eyes and joints.

Over time giardiasis can also prevent the body from absorbing nutrients that are necessary for the body.

How Is Giardiasis Diagnosed?

The diagnosis of giardiasis is made by testing the person’s stool sample. However, not all samples might contain Giardia; hence multiple stool tests are done. The doctor may also perform an endoscopy, where a thin, flexible tube is placed through the mouth to inspect the small intestine, followed by which a tissue sample is obtained from the small intestine for biopsy.

What Are the Treatment Options Available for Giardiasis?

Most people do not require treatment as the infection subsides in a few weeks unless they are likely to spread the disease. The doctor would advise antiparasitic medication for mild cases of giardiasis. However, in case of severe symptoms, antibiotics may be prescribed, like Metronidazole, Tinidazole, and Nitazoxanide. One must follow the healthcare provider’s instructions and take the medications in time. If the medication is not taken properly or stopped abruptly, this may lead to another infection as the previous one was not cleared, and the second course of medication.

What Are the Complications of Giardiasis?

Giardiasis symptoms usually go away after a few weeks of the infection; however, some serious complications linger even after the infection subsides:

  • Dehydration: This results from severe diarrhea when the body does not have enough water to function normally.

  • Malnutrition: Severe and chronic diarrhea due to giardiasis can lead to malnutrition in children and harm their mental and physical development.

  • Lactose Intolerance: Some people develop lactose intolerance following a giardiasis infection.

What Is the Long-Term Outlook for Giardiasis?

Giardiasis usually subsides two to six weeks after the infection and in severe cases, may subside with appropriate medications. However, a few complications like lactose intolerance may linger.

Can Pets Get Giardiasis?

Animals can acquire the disease from feces or another infected animal. Still, the chances of a pet spreading it to a person are relatively small, as the type of Giardia that infects humans is often different from the one in animals.

How to Prevent Giardiasis?

Currently, no medications can prevent giardiasis, but some simple precautions can save one from giardiasis.

  • Washing Hands Often: This could not only protect one from giardiasis but most infections can be prevented by washing hands often. Wash the hands with soap after a diaper change, using the toilet, before preparing food, and before eating. Alcohol-based sanitizers can also be used if necessary instead of soap and water.

  • Avoid Drinking Unsafe Water: Do not directly drink water from rivers or lakes; these may be contaminated. Make sure to drink filtered or boiled, or treated water only.

  • Avoid Swallowing Water While Swimming: Avoid swallowing water in pools, hot tubs, splash pads, etc. when swimming, and keep your mouth closed.

  • Wash Fruits and Vegetables: Wash all produce well before consuming or using them to prepare food.

  • Practice Safe Sex: Use condoms and perform only safe and protected sex.


Giardiasis is an infection that affects the small intestine caused by and causes diarrhea, stomach cramps, nausea, vomiting, malaise, etc. Most symptoms tend to subside a few weeks after the infection and are more likely to require no treatment. However, in severe cases, antibiotics are prescribed. The disease has never been fatal and has often been resolved by taking appropriate treatment as prescribed by the doctor.

Last reviewed at:
20 Feb 2023  -  4 min read




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