What is Giardia?

Giardia is a one-celled parasite that can cause a gastrointestinal illness caused giardiasis.

Where does Giardia come from?

Giardia is found in the feces of infected animals or humans. To become infected, a person must consume contaminated food or water including drinking from streams or rivers.

What are the symptoms of giardiasis?

Diarrhea, stomach cramps, bloating, gas, fatigue, or weight loss. These symptoms may last weeks. Infected persons may be contagious for months.

When do symptoms appear?

About seven to ten days after the organism is ingested, sometimes shorter or longer.

How is Giardia spread?

A person can be infected by drinking contaminated water or eating contaminated food. Direct or hand-to-mouth transfer of the parasite from human or animal feces can also cause infection. Many people have no symptoms but can pass the disease on to others if they do not wash their hands after changing diapers or using the toilet. Streams or lakes may be contaminated by animal feces and infect swimmers or hikers drinking contaminated water.

What is the treatment for giardiasis infection?

The choice of treatment depends on the patient's age and other health factors. If you think you or your child may have giardiasis, see a health care provider.

Who is at risk?

Anyone who consumes contaminated food or water is at risk. This includes those drinking contaminated water while camping or traveling, child care workers, young children who attend child care centers, persons exposed to human feces by sexual contact, and caregivers who might come in contact with feces while caring for a person infected with giardiasis. Children are especially susceptible because they put so many things into their mouths.

How common is giardiasis in Washington?

There are typically 700 to 900 cases a year.

How can I ensure my water is safe to drink?

Pay attention to health advisories and boil water notices. To ensure your drinking water is safe during boil water notices, always boil, filter or use bottled water.

  • Boiling water is the best way to ensure it is free of Giardia and other microorganisms. Bring the water to a rolling boil for three to five minutes. After it cools, put it in clean bottles or pitchers with a lid in the refrigerator. Use boiled water to brush your teeth, make ice, rinse food that will not be cooked, and to make baby formula or coffee (coffee makers do not get hot enough to kill Giardia).
  • Filters can collect Giardia and other germs from the water. Portable water filters also can be used at home or by campers to remove Giardia from the water. Read the label. It must state that the filter is effective for removing Giardia.
  • Bottled water may be a reasonable alternative to tap water, but the origin, quality and treatment of water before it is bottled varies considerably among companies and even among brands of water produced by the same company. Look for these words on the label: "Reverse osmosis treated," "Distilled," "Filtered through an absolute one micron or smaller filter." Carbonated water in cans or bottles is usually filtered or heated enough to remove Giardia. Fountain drinks made from tap water should be avoided during boil water notices.
  • Chemical disinfectants can be effective for Giardia. Follow the directions carefully.

What else can I do to avoid giardiasis?

The single, most effective way to avoid illness is to wash your hands often with soap and water. During boil water advisories, use water that has been boiled and cooled, filtered, or safely bottled for washing dishes, fruits and vegetables.

  • Always wash your hands before handling food and dishes and after using the toilet, gardening, changing diapers or handling pets or farm animals.
  • Avoid unpasteurized milk and dairy products.
  • Clean surfaces where diapers are changed after every use.
  • Do not swim in public pools or lakes if you have diarrhea.
  • Don't swallow water from lakes, rivers, pools or jacuzzis. Water swallowed accidentally while swimming may contain the organism.
  • Never prepare food for other people if you have diarrhea.
  • Take care when traveling in developing countries. Foods and drinks, in particular raw fruits and vegetables, tap water or ice made from tap water, unpasteurized milk or dairy products, and items from street vendors may be contaminated. Talk to your health care provider about other precautions you may want to take when traveling abroad.
  • Teach children to wash their hands before eating, and after using the toilet or touching animals.
  • Wash fruits, vegetables and dishes with safe water, especially if you plan to eat them raw. You can also peel fruit that you will not cook.

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