Giardiasis
What is giardiasis?
Giardia is a parasite (Giardia lamblia) that causes an intestinal infection in people and animals, referred to as giardiasis. Giardiasis has a worldwide distribution. Children are infected more often than adults, and infections are more common in the summer and fall. The infectious dose, or the amount needed to cause infection) may be as few as 10 cysts.
Signs and symptoms
- Diarrhea
- Fatigue
- Greasy stools that tend to float
- Abdominal cramping
- Excess gas or bloating
- Nausea/vomiting
- Foul-smelling stools
- Anorexia/weight loss
Incubation period
One to three weeks, commonly seven to 10 days
Contagious period and spread
Giardia is spread by the fecal→oral route and occurs by ingesting Giardia cysts from the stool of infected people or animals. People can become ill by drinking contaminated water, eating contaminated food, or coming into contact with infected animals. Person-to-person transmission can occur in child care centers and other institutions, but is uncommon. Giardia cysts have an outer shell that protects the parasite while outside of the body, making it hardy in the environment and on surfaces. The cysts can survive several months in cold water or soil, but are less persistent at warmer temperatures.
People are contagious as long as they have Giardia in their stool but are most contagious while having diarrhea. The parasite generally appears in the stool when symptoms begin and can sometimes remain in a person’s stool for several months.
Public health reporting requirements
- Staff who become aware of illness should report the infection to the facility director, school nurse, or child care health consultant.
- The facility should report to the state or local public health agency within four days of diagnosis.
- If other children or staff are ill with diarrhea, refer them to their health care provider and contact public health as soon as possible as this could be an outbreak. Generally speaking, it is considered an outbreak if there is an increase in the number of ill children and/or staff members at the school or child care center, or two or more cases of Giardia from different households.
- Suspected outbreaks should be reported to CDPHE or local health departments within four hours, even if the causative agent is not yet known.
Control of spread
- Consult with local or state public health on implementation of control measures.
- Encourage and teach the importance of frequent handwashing, especially after animal contact, using the toilet, changing diapers, before preparing food, and before eating. Sample signs showing when and how to wash hands are included on the department’s child care health regulations webpage under “Preventing illness” and in the hand hygiene section of this website. Post them or similar signs throughout the child care center or school to remind people to wash their hands.
- Promptly sanitize contaminated surfaces (like diaper-changing areas) and other commonly touched surfaces (like toys) and discard food or water if it is thought to be contaminated. See Disease Prevention: The Facility Environment.
- Untreated water (such as from lakes, ponds, springs, rivers, and streams) should not be used as drinking water unless it is boiled for at least one minute or adequately filtered and treated with chemical disinfectants like chlorine or iodine.
- Affected individuals should not swim or wade in pools or other recreational water until two weeks after their diarrhea has resolved.
- Alert possibly exposed family and staff members to watch for symptoms and provide them with prevention tips. See recommendations for parents/guardians/caregivers and the family section below.
Treatment
Illness lasts anywhere from one to six weeks and occasionally longer. Symptoms sometimes start and stop, so it can take several weeks before an ill person seeks medical care and is diagnosed. Many people infected with Giardia have no symptoms. Individuals experiencing symptoms can be treated with a variety of antiparasitic medications. Treatment of ill children with appropriate antibiotic/antiparasitic medication usually makes them non-infectious within a few days. Testing and treatment of students/children with no symptoms is not generally recommended.
Exclusion
- Child care
- EXCLUDE all infected children and/or caregivers who have diarrhea until at least 24 hours after diarrhea has resolved without the use of anti-diarrheal medications.
- Ill children should not go to another facility during the period of exclusion.
- Determine whether additional children have or have recently had diarrhea. Other children with diarrhea should be excluded, see a health care provider, and submit a stool sample.
- If additional cases are identified, work with public health and consider sending a letter home to parents/guardians.
- Primary and secondary school
- EXCLUDE all infected children experiencing symptoms and/or staff until at least 24 hours after diarrhea has resolved, without the use of anti-diarrheal medications.
- In general, students or staff with giardiasis who do not have diarrhea and are not otherwise sick may remain in school.
- In certain circumstances, public health may require additional testing before a person with infection can return to work, school, or child care.
- EXCLUDE affected individuals from food preparation until at least 24 hours after diarrhea has resolved, or they are cleared by the state or local public health agency.
Role of teachers, caregivers, and Family
- If your child or a child you care for is infected with Giardia, follow the advice of the child’s health care provider.
- Practice good handwashing, especially after changing diapers, going to the bathroom or helping a child go to the bathroom, or handling food. After changing diapers, wash the child’s hands as well as your own.
- It is also important to wash hands after touching pets or other animals as they can carry Giardia.
- Diapering, bathroom, and food preparation areas should be cleaned and disinfected frequently.
- Avoid drinking or serving untreated/unfiltered water from any natural water bodies, like streams, ponds, or lakes, untreated/unfiltered water while traveling in developing countries, or whenever the water quality is unknown.
- Avoid swallowing water when swimming. Lakes, streams, and other bodies of water, as well as swimming pools, can be contaminated with Giardia.
- To prevent others from becoming ill, individuals infected with Giardia should not swim or wade in pools or other recreational water until two weeks after their diarrhea has resolved.