Giardiasis is a parasitic infection that’s diagnosed by examining a stool sample and sometimes taking a tissue sample from the small intestine.

What is giardiasis?

Giardiasis is an infection in your small intestine. It’s caused by a microscopic parasite called Giardia lamblia. Giardiasis spreads through contact with infected people. And you can get giardiasis by eating contaminated food or drinking contaminated water. Pet dogs and cats also frequently contract giardia.

This condition can be found all over the world, according to the Centers for Disease Control and Prevention (CDC). However, it’s more common in overcrowded developing countries that lack sanitary conditions and water quality control.

G. lamblia are found in animal and human feces. These parasites also thrive in contaminated food, water, and soil, and can survive outside a host for long periods of time. Accidentally consuming these parasites can lead to an infection.

The most common way to get giardiasis is to drink water that contain G. lamblia. Contaminated water can be in swimming pools, spas, and bodies of water, such as lakes. Sources of contamination include animal feces, diapers, and agricultural runoff.

Contracting giardiasis from food is less common because heat kills the parasites. Poor hygiene when handling food or eating produce rinsed in contaminated water can allow the parasite to spread.

Giardiasis also spreads through personal contact. For example, unprotected anal sex can pass the infection from one person to another.

Changing a child’s diaper or picking up the parasite while working in a day care center are also common ways to become infected. Children are at high risk for giardiasis because they’re likely to encounter feces when wearing diapers or potty training.

Some people can carry giardia parasites without experiencing any symptoms. Symptoms of giardiasis generally show up one or two weeks after exposure. Common symptoms include:

You may have to submit one or more stool samples for testing. A technician will check your stool sample for giardia parasites. You could have to submit more samples during treatment. Your doctor may also perform an enteroscopy. This procedure involves running a flexible tube down your throat and into your small intestine. This will allow your doctor to examine your digestive tract and take a tissue sample.

In most cases, giardiasis eventually clears up on its own. Your doctor might prescribe medication if your infection is severe or prolonged. Most doctors will recommend treatment with antiparasitic drugs, rather than leaving it to clear up on its own. Certain antibiotics are commonly used to treat giardiasis:

  • Metronidazole is an antibiotic that needs to be taken for five to seven days. It can cause nausea and leave a metallic taste in your mouth.
  • Tinidazole is as effective as metronidazole, and often treats giardiasis in a single dose.
  • Nitazoxanide is a popular option for children because it’s available in liquid form and only needs to be taken for three days.
  • Paromomycin has a lower chance of causing birth defects than other antibiotics, although pregnant women should wait until after delivery before taking any medication for giardiasis. This medication is given in three doses over the course of 5 to 10 days.

Giardiasis can lead to complications such as weight loss and dehydration from diarrhea. The infection can also cause lactose intolerance in some people. Children under 5 years old who have giardiasis are at risk for malnutrition, which can interfere with their physical and mental development.

You can’t prevent giardiasis, but you can lower your risk of getting it by thoroughly washing your hands, especially if you work in places where germs spread easily, such as day care centers.

Ponds, streams, rivers, and other bodies of water can all be sources of giardia. Don’t swallow water if you go swimming in one of these. Avoid drinking surface water unless it’s been boiled, treated with iodine, or filtered. Bring bottled water with you when you go hiking or camping.

When traveling in a region where giardiasis occurs, don’t drink tap water. You should also avoid brushing your teeth with tap water. Keep in mind that tap water can also be present in ice and other beverages. Avoid eating uncooked local produce.

Be cautious about sexual practices associated with the spread of this infection, such as anal sex. Use a condom to reduce the chance of contracting giardiasis.

Giardiasis infections usually last about six to eight weeks, but problems such as lactose intolerance can persist after the infection clears up.