Giardia is a parasite that infects the intestines of humans and animals. When a person gets sick, the infection is called giardiasis. It is sometimes referred to as 'beaver fever'.
Giardiasis is a common infectious cause of diarrhea lasting more than 2 weeks. It is a common cause of diarrhea among individuals who drink water that has not been properly filtered, treated or boiled.
Giardia cysts can spread by water, food or fecal-oral transmission between infected individuals. Fecal-oral transmission occurs when contaminated feces particles are ingested.
Contaminated water is a major source of the spread of giardiasis. Giardia cysts can survive in lakes, ponds, creeks and streams. You can become infected if you drink or accidentally swallow contaminated water while you swim. You can also become infected by eating raw or undercooked food contaminated with cysts.
Giardia can also spread from person-to-person in settings such as child care centers. Young children who are not yet toilet-trained and where there is poor hygiene are most at risk. These children can also spread the infection to other people in their families.
Giardia can also spread during sexual activity when there is contact with feces.
Giardiasis may cause diarrhea, stomach cramps, gas, bloating, frequent loose and pale greasy stools, nausea, vomiting, weight loss and fatigue.
Symptoms usually appear 1 to 3 weeks after infection and can last for 2 to 6 weeks. Often you can be infected and have no symptoms. In some cases, symptoms can return after you have started to get better.
Prolonged and/or severe infection can result in reactive arthritis and damage to the cells lining the intestinal tract. This damage may cause your body to have trouble absorbing nutrients. These types of severe or prolonged infections are rare.
If you think you have giardiasis, speak with your health care provider for testing, advice and treatment. You may be asked to submit a stool sample for testing. Giardia can be difficult to detect, so you may have to submit more than 1 sample.
Some Giardia infections get better without treatment. Your health care provider will decide if treatment with anti-parasitic medication is necessary.
If you have diarrhea and/or vomiting from a Giardia infection, you should not go to work or school.
Do not swim in lakes, ponds, streams, rivers, swimming pools or hot tubs for at least 48 hours after the diarrhea and/or vomiting has stopped or as instructed by your local health authority. This will help to ensure that other swimmers do not become infected.
Wash your hands with soap and water after using the toilet and before eating or preparing food. Dry your hands with disposable towels.
If you are a food handler, health care worker or childcare worker, it is possible for you to spread Giardia to others. Stay home if you have diarrhea or vomiting. Do not return to work until at least 48 hours after your last episode of vomiting or diarrhea (whichever comes last) or as advised by your local health authority. Wash your hands often to help lessen the chance of spreading the infection to others.
Children in daycare who have diarrhea can be cared for in a supervised area away from other children until they are picked up by their parents. Children should not return to daycare until at least 48 hours after their last loose stool or episode of vomiting (whichever comes last) or as advised by your local health authority.
Children in daycare settings should be supervised by an adult when washing their hands. To learn about proper handwashing, visit HealthLinkBC File #85 Hand washing: Help stop the spread of germs.
Even after you feel better, Giardia may still be in your feces for several weeks and you can still infect others. After using the toilet and before eating or preparing food, wash your hands thoroughly with liquid soap and water.
To help prevent giardiasis, follow this advice:
If your water supply comes from an untreated surface water source or from ground water at risk of containing pathogens, you will need to disinfect it for all the following uses:
You can remove Giardia by using the following disinfection methods:
It is important to note that Giardia is moderately resistant to chlorine so treating water with chlorine is generally not effective in removing the parasite.
For more information on disinfecting water, visit HealthLinkBC File #49b Disinfecting drinking water, or contact your local environmental health officer.
For more information on the National Sanitation Foundation (NSF) International, visit www.nsf.org.
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