What Is A Giardia Infection? [Symptoms and Risk Factors]

That pristine lake you visit every summer may be breathtaking, but it could be hiding a dark secret. Giardia is a microscopic parasite found in contaminated food, water and soil. It’s the most common food-borne illness worldwide and in all regions of the United States. What is a Giardia infection, its risk factors and treatment options?

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It’s spread between people through improper hand-washing. Infection with this organism leads to inflammation of the gastrointestinal tract, leading to uncomfortable symptoms lasting anywhere from 10 days or longer.

What Is A Giardia Infection and How Do You Get It?

Giardia is known by many names, including: Giardiasis, Giardia intestinalis, Giardia lamblia, and Giardia duodenalis. These microscopic organisms live in the small intestines of their victims, and are passed in the feces. These cysts can survive in the environment, outside of the body, for a long period of time due to a hard outer covering. This protective shell makes Giardia tolerant to chlorine disinfection.

How, you might ask, does this nasty bug get into drinking water. Well, here’s a visual for you – millions of parasites can be released in just one bowel movement of an infected human or animal. Human and animal waste enters the water supply via faulty sewer systems, agricultural runoff or runoff from polluted storm water. Wells may become contaminated after a period of flooding, particularly if they become immersed. If you suspect your well may be contaminated, get it checked out quickly here.

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Risk Factors For Giardia

Most often associated with camping, Giardia is sometimes referred to as “Beaver Fever” or Hiker’s Diarrhea.” Although we’re all at risk for Giardia, certain subsets of people have an increased risk. For instance:

1. Caretakers of those infected with Giardia.

2. Those whose drinking water comes from an unclean source, such as, contaminated lakes, streams, and wells.

3. Children in daycare, and especially those in diapers, incur a greater risk of contracting Giardia.

4. Hikers and backpackers who drink out of contaminated streams and lakes.

5. Those who do not practice good hygiene put themselves at risk of infection.

6. Boaters and those who engage in water sports in infected rivers and lakes.

7. People who travel overseas.

8. Anyone exposed to human feces through care-taking or sexual contact.

9. Those living in developing countries with poor sanitation and contaminated water.

Recreational swimmers can acquire Giardia by swallowing contaminated lake water, or by swimming in infected pools and hot tubs. Remember Giardia is resistant to chlorine. Babies who swim in public pools can transmit the infection, through their diapers, into the water, putting other swimmers at risk.

Those who work in daycare centers should exercise caution when changing diapers. If they neglect to wash their hands after diapering, any surface they touch may put others at risk. Proper hygiene is key to not spread the infection.

 Symptoms Of Giardia

If you’ve been infected with Giardia, you may notice symptoms within a few days, but may not be symptomatic for up to three weeks. Symptoms may come on suddenly or develop over many days.

Look for the following:

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Infants and women who are pregnant are at higher risk of dehydration caused by the diarrhea characteristic of Giardiasis. This is not to be taken lightly, as dehydration can be life threatening, especially for babies. Assure they are drinking plenty of fluids to decrease their risk of dehydration.

Interestingly, the risk of becoming infected with Giardia from a pet is small as the type of Giardia that infects humans is a different variety. More on that below.

Giardia Treatment

The most effective way to diagnose Giardia is through a stool sample. Be aware that more than one specimen may be needed as testing for Giardia is difficult. Various prescription medications are used to treat Giardia, though some cases may clear on their own within a few weeks.

Severe cases may require a round of antibiotics. Metronidazole (Flagyl) and Tinidazole are the most commonly prescribed antibiotics for Giardiasis. Natural treatments are also available and effective. Options include olive leaf extract, Pico silver, bitters, garlic, black walnut hulls, wormwood, oregano oil,  grapefruit seed extract, and Paracid-X, a blend of anti-parasitic herbs.

To make sure your drinking water is safe, bring water to a hard boil for at least one minute. If you live at higher elevations, be safe, and boil the water for a minimum of three minutes. Tightly cover water and refrigerate.

Giardia And Pets

Dogs may also contract Giardia, with puppies being at the highest risk. Infection occurs when dogs drink contaminated water or if they come in contact with feces from an infected person. Fortunately, many dogs exposed to Giardia do not end up getting the disease.

If your dog has diarrhea that lasts more than a couple days, contact your veterinarian. Safe and effective medications are available to treat the infection. Symptoms include, not only diarrhea, but weight-loss, malaise, and in extreme cases, death.

The best and easiest way to prevent your pet from contamination is to assure they have clean drinking water from a safe source. If your pet does become infected, prevent future cases of parasitic infection by disposing of their feces immediately. Use gloves to protect yourself. The good news is Giardia is not typically spread from animals to humans.

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Key Points

The best way to prevent a Giardia infection is through proper hygiene, and avoiding contaminated food and water. Giardia is not uncommon. In fact, it is estimated that up to 20 percent of the population may be infected so educating yourself on effective preventative measures is just smart medicine.

Have you or someone you know been affected by Giardia? Let me know in the comments:)

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(1) NCBI: Giardia Lamblia Enteritis

(2) US National Library of Medicine National Institutes of Health: Advances in understanding Giardia: determinants and mechanisms of chronic sequelae

(3) US National Library of Medicine National Institutes of Health: Treatment of Giardiasis

(4) US National Library of Medicine National Institutes of Health: Biology of Giardia lamblia

(5) Sao Paulo Medical Journal: Cross-sectional epidemiological investigations of Giardia lamblia in children in Pakistan

(6) ResearchGate: Giardia

(7) CDC Centers for Disease Control and Prevention: Parasites – Giardia

(8) healthline: Giardiasis

(9) WebMD: Giardiasis

(10) Harvard Health Publishing Harvard Medical School: Giardiasis


Disclaimer: “I am not a medical doctor, and therefore, cannot diagnose or treat any medical condition, nor do I claim in any way to cure disease. Please be diligent and always do your own research in regard to any material I present on this site. I claim no responsibility for any distress, whether it be physical or emotional, that may occur as a result of the information you obtain from my blog.”




2 thoughts on “What Is A Giardia Infection? [Symptoms and Risk Factors]”

  1. Wow, I had no idea that up to 20% of the population might be infected with Giardia! That is a large number!! 

    Keeping dogs away from a water source on a hot day is not an easy thing to do, but I can see now that it’s important to know that they are drinking safe water. It’s great to read that not all exposed dogs will contract the disease, but it does point out the risks and should be a caution to dog owners to provide clean water for the best friend. 

    • Hi Aly,

      Yes, that’s pretty astounding that up to 20% of the population can be infected with Giardia. Kind of scary! I know what you mean about keeping dogs away from water, it’s very difficult! One of the lakes I visit every summer has Giardia so I know first hand how hard it is to keep the dogs safe. Thankfully, none of my pets have ever been infected. 

      Thanks so much for reading!


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