The prevalence of Giardia intestinalis in children in day care is quite a bit higher than the same age children not in day care. It is the most commonly diagnosed and most economically important parasite in people in the United States.
Giardia is a protozoan parasite that lives in the intestine of infected humans and animals (in particular, beavers and domestics animals like cats and dogs). It is found in the environment on surfaces (where it can survive for long periods of time), water and food that has been contaminated with the feces from an infected person or animal.
Children are more commonly infected than adults. The following have been implicated in both small and large community outbreaks:
Giardia is a particular problem in areas where children are not toilet-trained, like day care centers. In these cases, toys and other things the children touch may become contaminated with feces (even if it's not visible). The next child plays with the toys and puts his finger in his mouth and so on and so on.
Giardia is also an issue in recreational water like swimming pools, water parks, lakes and streams. In places where young children swim and may defecate in the water.
Hikers and campers can be at risk of infection if they drink stream or lake water that may be contaminated with infected human or animal feces.
Drinking water, using ice made from contaminated water and eating fruits and vegetables washed in contaminated water are all common ways to get infected with the parasite, particularly when traveling overseas. Sometimes it is of concern with well water if the well is located at the bottom of a hill or is shallow, because of run-off and flood water contaminating the well. Also if the well water is in an area where animals graze and the animal waste contaminates the ground water. There are situations where testing for Giardia in well water is warranted.
Chlorination is generally ineffective in killing the Giardia parasite, so if you can't avoid drinking potentially contaminated water, boil it or filter it with a filter that is rated for "cyst removal".
There are also documented cases of the parasite being transmitted via sexual contact (anal-oral).
Most cases of Giardia, up to 50%, are asymptomatic. If you do get sick, the symptoms of Giardia usually start about a week after getting infected. Symptoms can be divided between mild, acute and chronic infections.
Mild infection
This is typically moderate diarrhea followed by spontaneous recovery in 6 weeks.
Acute infection
This is characterized by sudden onset of explosive, foul-smelling, watery diarrhea without blood or pus, intestinal gas, abdominal cramps, nausea, excessive tiredness, bloating and chills. If left untreated, this can last for weeks or months.
Chronic infection
Chronic infection is often characterized by steatorrhea, greasy, frothy stools that float. This is due to the malabsorption of fats.
The diagnosis of Giardia is traditionally made by microscopic examination of stools to identify the parasite. Because of the way Giardia is shed, 3 negative stools are necessary to rule out the parasite. There are also tests for detecting antigens in stool or special immunofluorescent techniques (below right) which are generally more sensitive than microscopic examination.
Several prescription drugs are available to treat giardiasis including metronidazole and tinidazole. If the child is showing no symptoms, treatment is probably not necessary, but there are exceptions, consult with your doctor.
Now that we know the myriad of ways this common parasite can infect you, what preventive measures should you take? The Centers for Disease Control and Prevention recommend the following:
Practice good hygiene.
1. Wash hands thoroughly with soap and water.
a. After using the toilet and before handling or eating food, especially while having diarrhea.
b. After changing a diaper or assisting with toileting, especially if you are caring for diaper-aged children, even if you are wearing gloves.
c. After touching something that could be contaminated (such as a trash can, cleaning cloth, drain, or soil).
d. After handling animals or their toys, leashes, or feces.
2. Assist or visually supervise young children and other people you are caring for with hand washing as needed.
3. Protect others by not swimming if you are experiencing diarrhea and for 1 week after your diarrhea stops. This is essential for children in diapers.
4. Shower with soap and water before entering recreational water. Wash children thoroughly, especially their bottoms, with soap and water after they use the toilet or their diapers are changed and before they enter the water.
5. Keep Giardia and other germs out of pools, hot tubs, lakes, rivers, the ocean, etc. by taking the following steps:
Take children on frequent bathroom breaks or check their diapers often.
Change diapers in the bathroom or a diaper-changing area.
Avoid water that might be contaminated.
1. Do not drink untreated water from shallow wells, lakes, rivers, springs, ponds, and streams.
2. Do not drink untreated water or use ice made from untreated water during community-wide outbreaks of disease caused by contaminated drinking water.
3. Do not swallow recreational water.
4. Do not drink untreated water or use ice made from untreated drinking water in countries where the water supply might be unsafe.
Avoid food that might be contaminated.
1. Use safe, uncontaminated water to wash all food that is to be eaten raw.
2. Wash and/or peel all raw vegetables and fruits before eating.
3. Avoid eating uncooked foods when traveling in countries with minimal water treatment and sanitation systems.
And finally, avoid fecal exposure during sexual activity. This is especially important while experiencing diarrhea caused by giardiasis.
1. Use a barrier during oral-anal sex.
2. Wash hands immediately after handling a condom used during anal sex or after touching the anus or rectal area.
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