Giardiasis is an illness caused by a parasite called Giardia intestinalis. It lives in soil, food, and water. It may also be on surfaces that have been contaminated with waste. You can become infected if you swallow the parasite. You can also get it if you're exposed to human feces (poop) through sexual contact.

The risk of getting giardia is higher for travelers to countries where it is common, people in child care settings, and those who drink untreated water.

Diarrhea is the main symptom of giardia infection. Others include

• Passing gas
• Greasy stools
• Stomach cramps
• Upset stomach or nausea

These symptoms may lead to weight loss and loss of body fluids. Some people have no symptoms at all. Symptoms of infection often last two to six weeks. Stool sample tests can diagnose it. You often need to collect several samples to test. Doctors use several drugs to treat it.

The best way to prevent giardia infection is to practice good hygiene, including frequent hand washing. You should not drink water that may be contaminated. You should also peel or wash fresh fruit and vegetables before eating.

What is giardiasis?

Giardiasis is a diarrheal disease caused by the microscopic parasite Giardia. A parasite is an organism that feeds off of another to survive. Once a person or animal (for example, cats, dogs, cattle, deer, and beavers) has been infected with Giardia, the parasite lives in the intestines and is passed in feces (poop). Once outside the body, Giardia can sometimes survive for weeks or months. Giardia can be found within every region of the U.S. and around the world.

How do you get giardiasis and how is it spread?

Giardiasis can be spread by:

• Swallowing Giardia picked up from surfaces (such as bathroom handles, changing tables, diaper pails, or toys) that contain feces (poop) from an infected person or animal
• Drinking water or using ice made from water sources where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)
• Swallowing water while swimming or playing in water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams
• Eating uncooked food that contains Giardia organisms
• Having contact with someone who is ill with giardiasis
• Traveling to countries where giardiasis is common

Anything that comes into contact with feces (poop) from infected humans or animals can become contaminated with the Giardia parasite. People become infected when they swallow the parasite. It is not possible to become infected through contact with blood.

What are the symptoms of giardiasis?

Giardia infection can cause a variety of intestinal symptoms, which include:

• Diarrhea
• Gas or flatulence
• Greasy stool that can float
• Stomach or abdominal cramps
• Upset stomach or nausea
• Dehydration

These symptoms may also lead to weight loss. Some people with Giardia infection have no symptoms at all.

How long after infection do symptoms appear?

Symptoms of giardiasis normally begin 1 to 3 weeks after becoming infected.

How long will symptoms last?

In otherwise healthy people, symptoms of giardiasis may last 2 to 6 weeks. Occasionally, symptoms last longer. Medications can help decrease the amount of time symptoms last.

Who is most at risk of getting giardiasis?

Though giardiasis is commonly thought of as a camping or backpacking-related disease and is sometimes called "Beaver Fever," anyone can get giardiasis. People more likely to become infected include:

• Children in childcare settings, especially diaper-aged children
• Close contacts of people with giardiasis (for example, people living in the same household) or people who care for those sick with giardiasis
• People who drink water or use ice made from places where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)
• Backpackers, hikers, and campers who drink unsafe water or who do not practice good hygiene (for example, proper handwashing)
• People who swallow water while swimming and playing in recreational water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams
• International travelers
• People exposed to human feces (poop) through sexual contact

How is giardiasis diagnosed?

Your healthcare provider will ask you to submit stool (poop) samples to see if you are infected. Because testing for giardiasis can be difficult, you may be asked to submit several stool specimens collected over several days.

What is the treatment for giardiasis?

Many prescription drugs are available to treat giardiasis. Although the Giardia parasite can infect all people, infants and pregnant women may be more likely to experience dehydration from the diarrhea caused by giardiasis. To prevent dehydration, infants and pregnant women should drink a lot of fluids while ill. Dehydration can be life threatening for infants, so it is especially important that parents talk to their healthcare providers about treatment options for their infants.

My child does not have diarrhea, but was recently diagnosed as having a Giardia infection. My healthcare provider says treatment is not necessary. Is this correct?

Your child does not usually need treatment if he or she has no symptoms. However, there are a few exceptions. If your child does not have diarrhea, but does have other symptoms such as nausea or upset stomach, tiredness, weight loss, or a lack of hunger, you and your healthcare provider may need to think about treatment. The same is true if many family members are ill, or if a family member is pregnant and unable to take the most effective medications to treat Giardia. Contact your healthcare provider for specific treatment recommendations.

What can I do to prevent and control giardiasis?

To prevent and control infection with the Giardia parasite, it is important to:

• Practice good hygiene
• Avoid water (drinking or recreational) that may be contaminated
• Avoid eating food that may be contaminated
• Prevent contact and contamination with feces (poop) during sex

Can I get giardiasis from my pet?

The risk of humans acquiring Giardia infection from dogs or cats is small. The exact type of Giardia that infects humans is usually not the same type that infects dogs and cats.

Giardiasis is the most frequently diagnosed intestinal parasitic disease in the United States and among travelers with chronic diarrhea. Signs and symptoms may vary and can last for 1 to 2 weeks or longer. In some cases, people infected with Giardia have no symptoms.

Acute symptoms include:

• Diarrhea
• Gas
• Greasy stools that tend to float
• Stomach or abdominal cramps
• Upset stomach or nausea/vomiting
• Dehydration (loss of fluids)

Other, less common symptoms include itchy skin, hives, and swelling of the eye and joints. Sometimes, the symptoms of giardiasis might seem to resolve, only to come back again after several days or weeks. Giardiasis can cause weight loss and failure to absorb fat, lactose, vitamin A and vitamin B12.

In children, severe giardiasis might delay physical and mental growth, slow development, and cause malnutrition.

Diagnosis & Detection of Giardia Infection

Because Giardia cysts can be excreted intermittently, multiple stool collections (i.e., three stool specimens collected on separate days) increase test sensitivity. The use of concentration methods and trichrome staining might not be sufficient to identify Giardia because variability in the concentration of organisms in the stool can make this infection difficult to diagnose. For this reason, fecal immunoassays that are more sensitive and specific should be used.

Rapid immune-chromatographic cartridge assays also are available but should not take the place of routine ova and parasite examination. Only molecular testing (e.g., polymerase chain reaction) can be used to identify the subtypes of Giardia.

Treatment of Giardia Infection

Several drugs can be used to treat Giardia infection. Effective treatments include metronidazole, tinidazole, and nitazoxanide. Alternatives to these medications include paromomycin, quinacrine, and furazolidone. Some of these drugs may not be routinely available in the United States.

Different factors may shape how effective a drug regimen will be, including medical history, nutritional status, and condition of the immune system. Therefore, it is important to discuss treatment options with a healthcare provider.

General Epidemiology

Giardiasis is a diarrheal illness caused by the parasite Giardia intestinalis (also known as Giardia lamblia or Giardia duodenalis). A parasite is an organism that feeds off of another to survive.

Giardiasis is a global disease. It infects nearly 2% of adults and 6% to 8% of children in developed countries worldwide. Nearly 33% of people in developing countries have had giardiasis. In the United States, Giardia infection is the most common intestinal parasitic disease affecting humans.

People become infected with Giardia by swallowing Giardia cysts (hard shells containing Giardia) found in contaminated food or water. Cysts are instantly infectious once they leave the host through feces (poop). An infected person might shed 1-10 billion cysts daily in their feces (poop) and this might last for several months. However, swallowing as few as 10 cysts might cause someone to become ill. Giardia may be passed from person-to-person or even from animal-to-person. Also, oral-anal contact during sex has been known to cause infection. Symptoms of giardiasis normally begin 1 to 3 weeks after a person has been infected.

Giardia infection rates have been known to go up in late summer. Between 2006-2008 in the United States, known cases of giardiasis were twice as high between June-October as they were between January-March.

Anyone may become infected with Giardia. However, those at greatest risk are:

• Travelers to countries where giardiasis is common
• People in childcare settings
• Those who are in close contact with someone who has the disease
• People who swallow contaminated drinking water
• Backpackers or campers who drink untreated water from lakes or rivers
• People who have contact with animals who have the disease
• Men who have sex with men

The risk of humans acquiring Giardia infection from dogs or cats is small. The exact type of Giardia that infects humans is usually not the same type that infects dogs and cats.

Practice good hygiene.

• Everywhere
  • Wash hands with soap and clean, running water for at least 20 seconds; rub your hands together to make a lather and be sure to scrub the backs of your hands, between your fingers, and under your nails.
    • Before, during, and after preparing food
    • Before eating food
    • Before and after caring for someone who is sick
    • Before and after treating a cut or wound
    • After using the toilet
    • After changing diapers or cleaning up a child who has used the toilet
    • After blowing your nose, coughing, or sneezing
    • After touching an animal or animal waste
    • After handling pet food or pet treats
    • After touching garbage
  • Help young children and other people you are caring for with handwashing as needed.

• At childcare facilities
  • To reduce the risk of spreading the disease, children with diarrhea should be removed from child care settings until the diarrhea has stopped.

• At recreational water venues (for example, pools, beaches, fountains)
  • Protect others by not swimming if you have diarrhea (this is most important for children in diapers).
  • Shower before entering the water.
  • Wash children thoroughly (especially their bottoms) with soap and water after they use the bathroom or after their diapers are changed and before they enter the water.
  • Take children on frequent bathroom breaks and check their diapers often.
  • Change diapers in the bathroom, not by the water.
• Around animals
  • Minimize contact with the feces (poop) of all animals, especially young animals.
    • When cleaning up animal feces (poop), wear disposable gloves and always wash hands when finished.
  • Wash hands after any contact with animals or their living areas.
• Outside
  • Wash hands after gardening, even if wearing gloves.

Avoid water (drinking and recreational) that may be contaminated.

• Do not swallow water while swimming in pools, hot tubs, interactive fountains, lakes, rivers, springs, ponds, streams or the ocean.
• Do not drink untreated water from lakes, rivers, springs, ponds, streams, or shallow wells.
• Do not drink poorly treated water or ice made from water during community outbreaks caused by contaminated drinking water.
• Do not use or drink poorly treated water or use ice when traveling in countries where the water supply might be unsafe.
• If the safety of drinking water is in doubt (for example, during or after an outbreak, in a place with poor sanitation or lack of water treatment systems), do one of the following:
  • Drink bottled water.
  • Disinfect tap water by heating it to a rolling boil for 1 minute.
  • Use a filter that has been tested and rated by National Safety Foundation (NSF) Standard 53 or NSF Standard 58 for cyst and oocyst reduction; filtered tap water will need additional treatment to kill or weaken bacteria and viruses.

Avoid eating food that may be contaminated.

• Use safe, uncontaminated water to wash all food that is to be eaten raw.
• After washing vegetables and fruit in safe, uncontaminated water, peel them if you plan to eat them raw.
• Avoid eating raw or uncooked foods when traveling in countries with poor food and water treatment.

Prevent contact and contamination with feces (poop) during sex.

• Use a barrier during oral-anal sex.
• Wash hands right after handling a condom used during anal sex and after touching the anus or rectal area.

Clean up after ill pets and people.

Giardia is hard to completely eliminate from the environment, but you can decrease the risk of human infection or of your dog’s or cat’s reinfection if it has been ill. The risk of acquiring Giardia infection from your dog or cat is small, but there are some steps you can take to minimize your exposure.

Clean and disinfect your home in this way:

• Hard surfaces (for example: cement and tile floors, pet crates, tables, trash cans, etc.)
  • Cleaning
    • Wear gloves.
    • Remove feces and discard in a plastic bag.
    • Clean and scrub surfaces using soap. Rinse surface thoroughly until no obvious visible contamination is present.
  • Disinfection
    • Wear gloves.
    • Disinfect according to manufacturer guidelines using one of the following:
      • Quaternary ammonium compound products (QATS), which are found in some household cleaning products; the active ingredient may be listed as alkyl dimethyl ammonium chloride.
      • Bleach mixed with water (3/4 cup of bleach to 1 gallon of water).
    • Follow product instructions, ensuring the product stays in contact with the surface for the recommended amount of time.
    • Rinse with clean water.
• Carpet / Upholstered Furniture
  • Cleaning
    • Wear gloves.
    • If feces are on a carpet or upholstered furniture, remove them with absorbent material (for example, double layered paper towels).
    • Place and discard the feces in a plastic bag.
    • Clean the contaminated area with regular detergent or carpet cleaning agent.
    • Allow carpet or upholstered furniture to fully dry.
  • Disinfection
    • Wear gloves.
    • Steam clean the area at 158ºF for 5 minutes or 212ºF for 1 minute.
    • QATS are found in some carpet cleaning products and can also be used after cleaning to disinfect. Read the product labels for specifications, and follow all instructions.
• Other items (toys, clothing, pet bed, etc.)
  • Household items should be cleanedand disinfected daily while a dog or cat is being treated for Giardiainfection.
  • Dishwasher
    • Dishwasher-safe toys and water and food bowls can be disinfected in a dishwasher that has a dry cycle or a final rinse that exceeds one of the following:
      • 113ºF for 20 minutes
      • 122ºF for 5 minutes
      • 162ºF for 1 minute
      • If a dishwasher is not available, submerge dishwasher-safe items in boiling water for at least 1 minute (at elevations above 6,500 feet, boil for 3 minutes).
  • Washer and Dryer
    • Clothing, some pet items (for example, bedding and cloth toys) and linens (sheets and towels) can be washed in the washing machine and then heat-dried on the highest heat setting for 30 minutes.
    • If a clothes dryer is not available, allow clothes to thoroughly air dry under direct sunlight.

Giardia intestinalis (aka: Giardia duodenalis, Giardia lamblia) is a common, microscopic (intestinal) parasite that commonly affects humans, dogs, and cats.

Common signs and symptoms of Giardia infection (in both humans and pets) are diarrhea, gas, abdominal discomfort, nausea, and vomiting. However, it is possible to be infected and have no signs or symptoms of illness.

Can I get Giardia infection from my pet?

The risk of humans acquiring Giardia infection from dogs or cats is small. The exact type of Giardia that infects humans is usually not the same type that infects dogs and cats.

How is Giardia spread?

Anything that comes into contact with feces (poop) from infected humans or animals can become contaminated with the Giardia parasite. People and animals become infected when they swallow the parasite. It is not possible to become infected through contact with blood.

How does my dog or cat get infected with Giardia?

Your dog or cat might get infected by:

• Being in contact with infected feces (poop) from another dog or cat
• Rolling and playing in contaminated soil
• Licking its body after contact with a contaminated surface (for example, a dirty litter box or dog cage or crate)
• Drinking water from a contaminated creek, pond, or other body of water

Young pets, like puppies and kittens, have a higher risk of illness than adult dogs and cats.

How do I protect myself if my dog or cat has a Giardia infection?

The risk of acquiring Giardia infection from your dog or cat is small. However, there are some steps you can take to minimize your exposure to Giardia if you have dogs or cats:

• Wear gloves when gardening to reduce the risk of coming into contact with infected feces (poop) or soil.
• Clean household surfaces regularly.
• Clean and disinfect areas that your pet has access to—as well as items like toys, bedding, and water and food bowls—regularly.
• Wash hands frequently and properly:
  • Wet your hands with clean, running water (warm or cold) and apply soap.
  • Rub your hands together to make a lather and scrub them well; be sure to scrub the backs of your hands, between your fingers, and under your nails.
  • Continue rubbing your hands for at least 20 seconds.
  • Rinse your hands well under running water.
  • Dry your hands using a clean towel or air dry them.

If my pet has a Giardia infection, how do I clean and disinfect my house?

Giardia is hard to completely eliminate from the environment, but there are things you can do to decrease the risk of your pets’ reinfection and of human infection.

• Hard surfaces (for example: cement and tile floors, crates, tables, trash cans, etc.)
  • Cleaning
    • Wear gloves.
    • Remove feces and discard in a plastic bag.
    • Clean and scrub surfaces using soap. Rinse surface thoroughly until no obvious visible contamination is present.
  • Disinfection
    • Wear gloves.
    • Disinfect according to manufacturer guidelines using one of the following:
      • Quaternary ammonium compound products (QATS), which are found in some household cleaning products; the active ingredient may be listed as alkyl dimethyl ammonium chloride.
      • Bleach mixed with water (3/4 cup of bleach to 1 gallon of water)
    • Follow product instructions, ensuring the product stays in contact with the surface for the recommended amount of time.
    • Rinse with clean water.
• Carpet / Upholstered Furniture
  • Cleaning
    • Wear gloves.
    • If feces are on a carpet or upholstered furniture, remove them with absorbent material (for example, double layered paper towels).
    • Place and discard the feces in a plastic bag.
    • Clean the contaminated area with regular detergent or carpet cleaning agent.
    • Allow carpet or upholstered furniture to fully dry.
  • Disinfection
    • Wear gloves.
    • Steam clean the area at 158°F for 5 minutes or 212°F for 1 minute.
    • Quaternary ammonium compound products (QATS) are found in some carpet cleaning products and can also be used after cleaning to disinfect. Read the product labels for specifications, and follow all instructions.
• Other items (toys, clothing, pet bed, etc.)
  • Household items should be cleaned and disinfected daily while a dog or cat is being treated for Giardia infection.
  • Dishwasher
    • Dishwasher-safe toys and water and food bowls can be disinfected in a dishwasher that has a dry cycle or a final rinse that exceeds one of the following:
      • 113°F for 20 minutes
      • 122°F for 5 minutes
      • 162°F for 1 minute
      • If a dishwasher is not available, submerge dishwasher-safe items in boiling water for at least 1 minute (at elevations above 6,500 feet, boil for 3 minutes).
  • Washer and Dryer
    • Clothing, some pet items (for example, bedding and cloth toys) and linens (sheets and towels) can be washed in the washing machine and then heat-dried on the highest heat setting for 30 minutes.
    • If a clothes dryer is not available, allow clothes to thoroughly air dry under direct sunlight.

How do I reduce the amount of Giardia in my yard or outdoor environment?

Giardia is hard to completely eliminate from the environment, but there are things you can do to help decrease the risk of pet reinfection and of human infection. Please remember that despite your best efforts to clean the environment, Giardia can persist in outdoor spaces and pet reinfection is possible.

• Wear gloves when handling feces.
• Remove feces promptly and put them in a plastic bag.
• Limit access to common outdoor spaces, where possible, if pets have diarrhea or are being treated for Giardia.
• Eliminate any source of standing water (for example, puddles, containers with water, and fountains that are not in use).
• Do not attempt to use bleach or QATS in your soil or grass area, as they will be ineffective.
• Do not allow any new animals, especially young ones, to enter the yard or other outdoor space until advised by your veterinarian.

How long does Giardia survive in the environment?

• In the soil
  • In cold temperatures (around 4°C/39.2°F), Giardia can survive for approximately 7 weeks (49 days).
  • At room temperature (around 25°C/77°F), Giardia can survive for approximately 1 week (7 days).
• Dry vs. moist surface or environment
  • In a dry, warm environment that experiences direct sunlight, Giardia can survive for only a few days.
  • In a moist, cool environment, Giardia can survive for up to several weeks.
• Water
  • In water temperatures below 10°C/50°F (for example, lake water or puddle water during the winter, refrigerated water), Giardia can survive for 1–3 months.
  • In water temperatures above 10°C/50°F (for example, river water during the fall, tap water, and puddles during the summer), Giardia can survive for less time than in colder temperatures. For example, in water above 37°C/98.6°F, Giardia can survive less than 4 days.

How often and for how long should I clean and disinfect my home after my dog or cat is diagnosed with Giardiainfection? collapsed

• Clean and disinfect potentially contaminated items (toys, water bowls and food bowls, pet bedding, floors, dog crates, linens, towels, litter box, etc.) regularly for as long as your pet is sick.
• If your pet is taking medication, clean and disinfect frequently (daily if possible) until a few days after the last dose of medication is given.
• Giardia survival depends on many factors, so we recommend that you consult your veterinarian for further advice.

How do I prevent my dog or cat from getting re-infected, or sickening my other pets, during treatment?

• If you have other dogs or cats, make sure you tell your veterinarian even if they are not showing signs of diarrhea. Other pets may also be put on medicine depending on the situation. Even animals showing no signs of Giardia infection could be infected and shedding Giardia into the environment.
• Bathe all household pets with pet shampoo following medical treatment to ensure no fecal residue is in the pet’s coat.
• Clean dogs’ and cats’ environment, as described above, (holding areas, floors, crate, etc.) and wash water bowls daily with soap and water.
• Limit your dog’s access to untreated surface water (creeks, ponds, lakes) to avoid re-infecting your animal and contaminating the water which could make other animals sick.

How do I treat my pet for Giardia infection?

• If your pet has persistent diarrhea, seek veterinary care. Diarrhea has different causes and could result in dehydration or other serious complications.
• Diagnosis and treatment of Giardia infection must be done by a licensed veterinarian.
• No approved over-the-counter treatment is available for Giardia infection.
• Giardia can be passed in stool intermittently, and an animal may appear healthy or without signs of disease before it stops passing Giardia. Repeated fecal tests may be necessary.
• Follow your veterinarian’s recommendations, and take your pet to all follow-up appointments.

Where and how does Giardia get into drinking water?

Millions of Giardia parasites can be released in a bowel movement of an infected human or animal. Human or animal waste can enter the water through different ways, including sewage overflows, sewage systems that are not working properly, polluted storm water runoff, and agricultural runoff. Wells may be more vulnerable to such contamination after flooding, particularly if the wells are shallow, have been dug or bored, or have been submerged by floodwater for long periods of time.

How can I find out whether there is Giardia in my drinking water?

If you suspect a problem and your drinking water comes from a private well, you may contact your state certification officer for a list of laboratories in your area that will perform tests on drinking water for a fee.

How can I remove Giardia from my drinking water?

To kill or inactivate Giardia, bring your water to a rolling boil for one minute (at elevations above 6,500 feet, boil for three minutes) Water should then be allowed to cool, stored in a clean sanitized container with a tight cover, and refrigerated.

An alternative to boiling water is using a point-of-use filter. Not all home water filters remove Giardia. Filters that are designed to remove the parasite should have one of the following labels:

• Reverse osmosis,
• Absolute pore size of 1 micron or smaller,
• Tested and certified by NSF Standard 53 for cyst removal, or
• Tested and certified by NSF Standard 53 for cyst reduction.

As you consider ways to disinfect your well, it is important to note that Giardia is moderately chlorine resistant. Contact your local health department for recommended procedures. Remember to have your well water tested regularly, at least once a year, after disinfection to make sure the problem does not recur.