Giardia and Drinking Water
Barbara Liukkonen, Water Resources Education Coordinator, author and contact
Craig Hassel, Extension Specialist, Food and Nutrition, contact
Giardiasis is a gastrointestinal disease caused by a minute parasite often transmitted through water supplies. The parasite, giardia, passes through several life stages in humans and other warm-blooded animals, such as beaver, muskrat, or mink. When it is between parasitic stages, it forms a protective cyst. This protective cyst allows the giardia parasite to survive for long periods outside the animal host.
Symptoms of giardiasis include diarrhea or increased gas, nausea, loss of appetite, abdominal cramps, and bloating. Weight loss may occur from nausea and loss of appetite. These symptoms may appear a few days to a few weeks after exposure, and may last up to six weeks or recur intermittently over several months.
Although other diseases may have similar symptoms, you should suspect giardiasis if you have been drinking untreated water. Giardiasis is often undiagnosed, but may be indicated by ongoing or recurrent bouts of intestinal illness. The disease is generally not life-threatening and, with proper diagnosis and treatment, it is curable with medication.
Giardiasis is transmitted through contaminated water or through direct contact under unsanitary conditions. Giardiasis is known by other names such as a campers' or hikers' disease. It is caught by people drinking unpurified water. Today giardiasis is often transmitted between people "back home." This frequently occurs at day care centers, where the parasite may be passed by toddlers just being toilet trained or during diaper changing. Thorough hand-washing is the best defense against this form of transmittal.
Improper waste water treatment or a faulty septic system connection contaminates household water supplies. Giardiasis and other intestinal illnesses may be passed from family member to family member and on to guests through groundwater contamination.
Giardiasis is caught in the wilderness, and is in fact becoming more widespread. Several precautions limit your chances of contracting giardiasis while camping. Carry a safe water supply with you. If that is not possible take your water from near the center of a lake, not from near shore or from a stream. Although running water in a stream may look cleaner, it is actually more likely to be contaminated. Fill your container from as far under the water surface as possible. Then before drinking follow one of the steps below to purify it.
Boiling water for 3-5 minutes is the surest way to destroy the giardia cysts. Filters are often ineffective even if they say they remove giardia. The cysts are only about 6 microns (6 one-thousandths of a millimeter) in diameter and most filters have larger pore sizes than that.
If a filter is used, select one with a pore size of 1 micron or less. Charcoal filters are not effective in removing giardia, and some filters that do remove giardia may not remove bacteria and viruses that cause diarrhea.
Purification tablets may work if the package specifically states that they are effective against giardia. If you use purification tablets, it is critical that you follow the directions exactly, use enough chemical, and allow the water to stand the required amount of time for complete treatment. Insufficient exposure time will prevent complete elimination of the cysts. At this time chemical purification is not recommended as a way to kill the giardia parasite.
For information on water testing services, water treatment devices, and giardia in your drinking water, contact your community health service or your Minnesota Extension Service county office.
For additional information about giardia and drinking water, contact:
Barbara Liukkonen
Water Resources Education Coordinator
Water Resources Center
173 McNeal Hall
1985 Buford Ave.
Saint Paul, MN 55108
Phone: (612) 625-9256
Craig Hassel
University of Minnesota Extension
225 Food Science and Nutrition Bldg.
University of Minnesota
1334 Eckles Ave.,
St. Paul, MN 55108
Phone: (612) 624-7288
Minnesota Department of Health
Building:
Well Management Section
Environmental Health Division
Minnesota Department of Health
625 North Robert Street
St. Paul, MN 55155-2538
Mailing:
Well Management Section
Environmental Health Division
Minnesota Department of Health
P.O. Box 64975
St. Paul, MN 55164-0975
Phone: (651) 201-4600 |
