What causes Giardiasis?

Giardiasis is caused by the microscopic parasite Giardia lamblia, which infects the small intestine when you swallow contaminated water or food. This parasite lives in the intestines of infected people and animals and spreads through feces. You can contract Giardia by drinking untreated water from lakes, rivers, or streams, eating contaminated food, or through person-to-person contact, especially in daycare centers or when caring for someone infected.

What is the best test for Giardiasis?

The Ova & Parasites with Giardia Antigen stool test is the most important test for Giardiasis because it uses two detection methods to identify the parasite. This comprehensive test combines traditional microscopic examination with enzyme immunoassay (EIA) technology to detect Giardia antigens in your stool. The dual approach identifies both the parasite directly and the specific proteins it produces, making it more accurate than single-method testing. A positive result for Giardia antigens confirms an active infection that requires treatment.

When should I get tested for Giardiasis?

You should get tested if you experience persistent watery diarrhea lasting more than a few days, especially after camping, hiking, or traveling to areas with poor sanitation. Other reasons to test include unexplained stomach cramps, bloating, nausea, or foul-smelling greasy stools. You should also get tested if you work in a daycare center, have been in contact with someone diagnosed with Giardia, or recently drank untreated water from streams or lakes.

What are the symptoms of Giardiasis?

Giardiasis symptoms include watery diarrhea, stomach cramps, bloating, and excessive gas. You might notice greasy stools that float, nausea, and dehydration from fluid loss. Some people experience weight loss, fatigue, and loss of appetite. Symptoms typically appear 1-3 weeks after infection and can last for weeks or months if left untreated. However, some infected people have no symptoms at all but can still spread the parasite to others.

Who is at risk for Giardiasis?

Children in daycare centers and their caregivers face higher risk due to close contact and diaper changing. Hikers, campers, and travelers who drink untreated water from natural sources are vulnerable to infection. People with weakened immune systems, those living in areas with poor sanitation, and anyone in close contact with infected individuals also have increased risk. Pets can carry Giardia, so people who handle animal waste regularly should take extra precautions.

What happens if Giardiasis is left untreated?

Untreated Giardiasis can lead to severe dehydration from persistent diarrhea, especially in children and elderly adults. Chronic infection causes malabsorption of nutrients, resulting in significant weight loss and nutritional deficiencies. Some people develop lactose intolerance that persists even after the infection clears. Long-term Giardiasis can cause chronic digestive problems and interfere with normal daily activities. Without treatment, you also risk spreading the infection to family members and others in close contact.

Can Giardiasis be diagnosed with a blood test?

Giardiasis cannot be diagnosed with a blood test because the parasite lives in the intestines, not the bloodstream. The most accurate diagnosis requires a stool test that detects either the Giardia parasite itself or the antigens it produces. The Ova & Parasites with Giardia Antigen stool test is specifically designed to identify this intestinal infection. Multiple stool samples collected over several days may be needed because the parasite is not always present in every bowel movement.

How is Giardiasis treated?

Giardiasis is treated with prescription antiparasitic medications such as metronidazole, tinidazole, or nitazoxanide. Your healthcare provider will prescribe the medication based on your symptoms, age, and overall health. Most people recover within a few weeks of starting treatment. During treatment, drink plenty of fluids to prevent dehydration and avoid alcohol, which can interact with some medications. Your doctor may recommend retesting after treatment to confirm the infection has cleared completely.

How can I prevent Giardiasis?

Prevent Giardiasis by washing your hands thoroughly with soap and water, especially after using the bathroom, changing diapers, and before preparing food. Avoid drinking untreated water from lakes, rivers, or streams, and use water filters or boil water for at least one minute when camping. Peel or thoroughly wash fruits and vegetables, especially when traveling internationally. Practice safe food handling, avoid swallowing water while swimming in pools or natural bodies of water, and maintain good hygiene if caring for someone with Giardiasis.

What can I do at home for Giardiasis?

Stay well-hydrated by drinking plenty of water, clear broths, and oral rehydration solutions to replace fluids lost from diarrhea. Rest as much as possible to help your body fight the infection. Eat bland, easy-to-digest foods like rice, bananas, toast, and applesauce while avoiding dairy products, fatty foods, and caffeine. Maintain strict hand hygiene to prevent spreading the infection to others. However, home care does not replace medical treatment with antiparasitic medications, which are necessary to eliminate the infection completely.

Getting your blood test with us is easy, private & backed by the power of science.Long story short: In the test options, use the filters or search box to narrow your choices and find the test you want. If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test. Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout. If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want. When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system. Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way. You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy! If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.

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Is it possible to make changes to my lab order if I made a mistake with the name, date of birth, or any other details?

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During the ordering process, you’ll be able to select a specific lab near you, with no strings attached! You can switch it up later easily and visit any of our authorized locations as long as it’s the same lab company you selected your test for (Quest Diagnostics or Labcorp). Before you proceed with your order, feel free to browse through all our lab locations here. This will give you the peace of mind of knowing that there's a lab nearby your home, office or your favorite gym. If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.

Giardiasis Stool Test | Private MD Labs

Giardiasis Blood Test & Stool Analysis

What is Giardiasis?

Giardiasis is an intestinal infection that causes diarrhea, gas, and abdominal cramps. It is caused by the microscopic parasite Giardia lamblia, which infects the small intestine. The Ova & Parasites with Giardia Antigen stool test is the most important test for diagnosis.

Written by Private MD Labs Medical Team

Last updated: December 29, 2025

Getting your blood test with us is easy, private & backed by the power of science.

Long story short:

In the test options, use the filters or search box to narrow your choices and find the test you want.
If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test.
Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout.
If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want.
When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system.
Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way.
You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy!

754-799-7833

support@privatemdlabs.com