Giardia is a one-celled parasite that can cause gastrointestinal illness in humans and animals. Illness caused by Giardia is called giardiasis.
Symptoms of Giardiasis
Symptoms include diarrhea, stomach cramps, bloating, gas, fatigue, and weight loss. Symptoms generally appear one to two weeks after becoming infected with Giardia, and they can last for weeks. Infected people might be contagious for months.
How People Get Infected
Giardia is found in the poop of infected animals and humans. A person must consume contaminated food or water to become infected. This includes drinking from contaminated streams and rivers, which can infect swimmers or hikers. Direct hand-to-mouth transfer of the parasite from human and animal poop can also lead to an infection. Many people have no symptoms, but they can pass the disease on to others if they do not wash their hands after changing diapers or using the toilet.
Who Gets Sick
Anyone can get sick from Giardia. This includes people who drink untreated water while camping or traveling, child care workers, young children who attend child care centers, people exposed to human poop by sexual contact, and caregivers who might come in contact with poop while caring for a someone who is infected with Giardia. Children are especially susceptible because of how frequently they put items into their mouths.
How to Prevent Giardia Infection
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 you handle food and dishes and after you use the toilet, garden, change diapers, or handle pets or farm animals.
- 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 can contain the organism.
- Never prepare food for other people if you have diarrhea.
- Take care when traveling abroad where water may not undergo the same treatment as in the United States. Foods and drinks with a higher risk for contamination include raw fruits and vegetables, tap water or ice made from tap water, unpasteurized milk or dairy products, and items from street vendors. Talk to your health care provider about precautions you might want to take when traveling abroad.
- Teach children to wash their hands before they eat, after they use the toilet, and after they touch 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.
Boil Water Advisories
Pay attention to health advisories and boil water notices. To ensure your drinking water is safe during boil water notices, always boil it, filter it, or drink bottled water.
- Boiling water is the best way to ensure it is safe. Bring the water to a rolling boil for 3 to 5 minutes. After it cools, refrigerate it in clean bottles or pitchers with lids. Use boiled water to brush your teeth, make ice, rinse food that will not be cooked, and make baby formula or coffee (coffee makers do not get hot enough to kill Giardia). Check if any purchased prepared foods and beverages were made with safe water.
- Filters can collect Giardia and other germs from the water. Portable water filters can be used at home or by campers to remove Giardia. Before using a filter, read the label. It must state that the filter is effective for removing Giardia.
- Bottled water may vary in origin, quality, and treatment before it is bottled. Look for these words on the label: "Reverse osmosis treated," "distilled," or "filtered through an absolute one micron or smaller filter." Carbonated water in cans or bottles is usually filtered or heated enough to remove Giardia. Avoid fountain drinks made from tap water during boil water notices.
- Chemical disinfectants can be effective for Giardia. Follow the directions carefully.
Treatment for Giardiasis Infection
A health care provider might prescribe medicine to treat giardiasis. 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.