What is Giardia?

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Giardia, also called Giardia lamblia, is a type of single celled, flagellated protozoa. It lives in the small intestine of its host and can infect humans. This parasite also infects other vertebrates and commonly infects domestic cats.

People or animals who are infected develop a disease called giardiasis, which is marked by abdominal cramps and diarrhea. Other symptoms include nausea, vomiting, weight loss, fatigue, bloating, and flatulence. Symptoms typically last about two to six weeks. Each year, the parasite infects many individuals around the world, and it is a top, non-bacterial cause of diarrhea in North America.

Found in the fecal matter of infected humans and animals, the protozoa is typically ingested by accident. This often happens when an individual places something in his or her mouth that has come into contact with the fecal matter of an animal or human infected with the parasite. Frequently, accidental ingestion is the result of improper hand washing.

Water is another frequent route of infection. The parasite may be found in swimming pools, hot tubs, streams, ponds, rivers, and lakes that have been contaminated with feces or sewage. Often, individuals accidentally swallow contaminated water when using such bodies of water for recreational pursuits.


A person with giardiasis can spread the infection unintentionally. To avoid doing so, proper hand washing techniques should be observed after using the toilet and before eating and meal preparation. Additionally, an infected individual should avoid swimming in recreational waters for at least two weeks after symptoms have stopped.

It is possible for a person with a giardia infection to be asymptomatic, meaning that he or she exhibits no symptoms of the disease. An asymptomatic individual may still spread the parasite to others.

An infection is determined by examining the stool of the suspected host. Often, the parasite is difficult to detect and a medical professional may require several stool samples to make an accurate diagnosis. Once confirmed, infection is treated using prescription medications.

To prevent infection, proper hand washing is key. It is also imperative to avoid swallowing water used for recreation. People shouldn't drink untreated water from lakes, ponds, streams, and shallow wells. Furthermore, it is wise to avoid drinking water and using untreated ice in countries in which the water supply is questionable.

In particular, campers may be at increased risk for consuming giardia. Scientists believe this happens when campers drink stream water contaminated with animal or human feces. To avoid infection, water obtained from untreated wilderness sources should always be boiled. Additionally, there are filters available that are effective at removing the parasite from water.


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Post 6

My brother is confined in the hospital for one week now because he defecated bright red blood. The doctor can't find where the blood is coming from. He has already undergone an endoscopy and colonoscopy. What disease could this be? Please help us.

Post 3

Do giardia symptoms ever last for a shorter time than two weeks? It seems like if it did, it would be very easy to assume you had just a regular stomach bug, and you may not even know you had this parasite that you could spread to others.

I guess the point is to always wash your hands good and make sure you aren't doing anything that could spread an illness or a parasite to other people.

Post 2

I have a friend who always stops to drink from streams when we are hiking in the woods. I have always been nervous about it, so I haven't tried it. He's convinced there's nothing wrong with it because it has never caused him any problems before.

Even though knowing about it would be enough to make me stop drinking from streams, I doubt it will even phase him when I tell him. I'll make sure to let him know what the symptoms of giardia are too. It may be information he has use of in the future if he doesn't change his ways!

Post 1

My 2 year old son is suffering from Giardia. Preliminary he is treated with Tinidikon. Please suggest what needs to be done and what are easily available drugs in the Indian market.

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