What is Giardiasis?

Giardia is a microscopic animal that lives in freshwater and feces. When people accidentally drink water with giardia living in it, the giardia makes a new home in the human intestine. This causes the medical condition known as giardiasis.

Killing the giardia is paramount to getting cured. Dogs and cats also get giardiasis but they need treatments that differ from human treatments. It is possible to contract giardiasis from an infected pet but unlikely. Babies that have been infected can pass on the parasites through their feces and diapers. Infected men may spread the parasite through unprotected anal sex. It is important to use condoms, drink only boiled water when tap or bottled water is unavailable and wash hands often to prevent many illnesses, including giardiasis.

What are the Symptoms of Giardiasis?

Common symptoms include diarrhea or stools that appear greasy, abdominal cramps or other pains, gas, bloating, constant fatigue, headaches, nausea with or without vomiting and loss of appetite. People who begin to show symptoms have been infected with the microscopic parasite for at least one week.

Unusual symptoms are swollen joints, swollen eyes, itchy skin and hives on the skin. Over time, the person loses weight no matter how much he or she eats.

People who are affected by excessive vomiting and diarrhea are at high risk of becoming dangerously dehydrated. If the person cannot keep down water and has trouble staying awake, they should call a doctor at once.

Giardiasis Causes

This condition is caused by a parasitic infection. The Giardia parasite is found in the intestines of both humans and animals. They are microscopic organisms that are passed from the body into the stool. Once inside the stool and out of the body, they can stay alive for months. Once they are ingested by a host, the parasites are released from a hard shell and infect that host. They are most commonly passed to a human host when that person drinks contaminated water. This parasite lives in lakes, rivers, streams, and ponds. It can also live in spas, swimming pools, wells, water parks, cisterns and municipal water. Agricultural runoff and wildlife can also cause surface and groundwater to be contaminated.

Giardia parasites can also be passed by food that has been contaminated by food handlers or by the ingredients themselves being contaminated at the agricultural site. The parasite can also be passed by person-to-person contact. It is common to catch this infection through contaminated diapers. It can also be passed through anal sex.

How is Giardiasis Treated?

Patients can kill off the parasites with anti-parasite drugs or antibiotics like metrodinazole or tinidazole (brand name Tindamax). Depending on how heavily the patient is infested, treatments may range from one dose to many days taking pills or liquid medications. Patients who cannot keep medication down may need medication given intravenously.

These medications can cause birth defects. Pregnant women or women who think they may be pregnant need to tell their doctors about their condition before taking any medication. Paromomycin is the gentlest antibiotic to give pregnant women.

Giardiasis Prevention

One of the best ways to prevent Giardiasis is to wash your hands regularly, especially before preparing food and before eating it. If you change diapers, wash your hands thoroughly with soap after doing so as well as after using the bathroom. If you work in a daycare or hospital where you change diapers, protect yourself from fecal contamination by following hand-washing protocol and disposing of diapers properly. If you come into contact with farm animals or otherwise come across animal fecal matter, wash thoroughly afterward. Always wash raw produce before you eat it.

In shared water environments, avoid swallowing any water and avoid getting water splashed into your mouth. The parasite can live in virtually any body of water, including the water found in spas. Always clean yourself after leaving any body of water, including rivers, swimming pools, fountains, and lakes. Any water that you enter could be contaminated.

Last Reviewed:
September 21, 2016
Last Updated:
December 27, 2017