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Giardia and Cryptosporidium?
The information below is taken directly from the Pennsylvania Department of Environmental
Resources. While these protozoa can be a serious problem as an infectious agent, please read the most often asked questions listed below BEFORE you decide either you have a problem or wish to expend the considerable sum of money necessary for analysis
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What are Giardia and Cryptosporidium?
Giardia and Cryptosporidium are widespread intestinal parasites that cause
diarrheal illnesses in people and some wild and domesticated animals. They are not bacteria or viruses, but protozoa with complex life cycles. Giardia and Cryptosporidium exist in a cyst form, very much like a
microscopic egg. When even a few cysts are consumed, they enter the small intestine, where they ex-cyst or "hatch" and can multiply into millions of protozoa. These organisms complete their life cycle
within the intestine after which they may again form a resistant Giardia cyst or Cryptosporidium oocyst.
Sometimes, infected people or animals excrete them back into the environment, but all the cysts and oocysts are in "suspended
animation" and cannot multiply or move about.
What illnesses do they cause?
As few as 10 cysts can cause "giardiasis," a flu-like illness with symptoms involving persistent
diarrhea, nausea, abdominal cramps, weight loss and sometimes dehydration. The symptoms of "cryptosporidiosis" are similar to those of giardiasis, although the number of oocysts needed to induce this
illness is still uncertain. Typically, the symptoms appear within one week after the ingestion of cysts or oocysts. Both illnesses are usually acute, lasting 10 to 14 days, but they can become chronic and last up to
one or two months. Individuals with weakened immune systems (i.e., those with AIDS, people receiving treatment for certain cancers, organ transplant recipients, etc.) are especially susceptible, as well as the
elderly, infants, and malnourished children. Although cryptosporidiosis can be fatal for people with weakened immune systems, most people recover from these diseases within a short time. Not all individuals are
symptomatic - that is, a number of carriers excrete cysts or oocysts for months or years without knowing they have a disease.
How are people infected?
Giardia and Cryptosporidium are strictly gastrointestinal organisms, meaning that they cannot be transmitted through a cut in the
skin or by touching the blood of an infected individual. Cysts and oocysts are commonly transmitted from the environment to humans through inadequately or improperly treated drinking water. They may also be acquired
by eating contaminated food or by personal contact with an infected person or animal. Children are particularly susceptible since they may ingest these protozoa through the fecal-oral route, such as playing with
toys of an infected child and then putting their own hands or toys in their mouth.
How prevalent are giardiasis and cryptosporidiosis?
At one time, Pennsylvania was among the leaders nationally in the number of recorded waterborne disease
outbreaks. Since 1979, eight documented giardiasis outbreaks and one cryptosporidiosis outbreak have occurred, though it is possible that many other illnesses may have been confused with the "common flu"
or misdiagnosed as some other illness. Overall, more than 600,000 people in the Commonwealth have been affected by boil water advisories that were issued as a direct result of drinking water contamination or
giardiasis and cryptosporidiosis outbreaks. At the national level, the most notable outbreak in Milwaukee, Wisconsin, in 1993 resulted in over 400,000 confirmed cases of cryptosporidiosis, including several deaths
that occurred among immune-compromised individuals. All of these outbreaks were attributed to inadequate treatment or improperly operated water treatment facilities.
Neither Giardia nor Cryptosporidium are "new" parasites, probably having been around for a long time. Techniques to identify these organisms and their associated
diseases have only been developed relatively recently, however. For example, Cryptosporidium wasn't recognized as an important cause of human diarrheal illness until 1982, while Giardia was first widely
recognized as a source of waterborne illness in the 1970s.
Do all water supplies contain Giardia and Cryptosporidium?
Most surface water sources either contain or are vulnerable to Giardia cyst and Cryptosporidium
oocyst contamination at one time or another. Since some people are carriers, cysts and oocysts may enter the water through treated and untreated sewage outfall. Of particular concern are those animals that live in
or near the water, since they are likely to deposit cysts and oocysts directly into drinking water supplies. Livestock are notorious carriers of Cryptosporidium, while beaver have been implicated as a carrier of
Giardia. Once in the water, both protozoan cysts remain capable of infecting a host for many months, especially in colder water where they are more resistant to natural die-off.
Since many animals are carriers of cysts and oocysts, you should never drink untreated water from even the clearest looking stream or river. Giardiasis became famous as the
"backpacker's disease" because so many unsuspecting hikers and backpackers often became ill after drinking water directly from clear, mountain streams.
You should also avoid untreated spring water--no matter how clean it looks--because cysts, oocysts, bacteria and viruses may contaminate the spring supply at any time.
A properly constructed well is an unlikely source of Giardia and Cryptosporidium because the natural filtering action of the soil removes cysts and oocysts before they
enter the ground water. Some wells, though, may involve a risk if they are improperly constructed and allow direct infiltration of surface water, or if they obtain water from aquifers that do not have sufficient
natural filtration.
How are cysts and oocysts removed from drinking water supplies?
Because many animals harbor these diseases, it is impossible to stop the introduction
of Giardia and Cryptosporidium into a surface-water supply. The only reliable long-term measure to protect consumers against waterborne diseases is a properly designed and operated filtration and disinfection
treatment plant.
Because Cryptosporidium is smaller and more resistant to disinfection than Giardia, it is particularly important that Pennsylvania's Safe Drinking Water Program
has taken a "multiple barrier" approach to protecting public water supplies. The first barrier is the protection of the source water quality to minimize contamination through pollution control laws and
local municipal action.
The second barrier--the most effective method of protecting a drinking water system from disease-causing organisms--is a well-operated filtration plant. In themselves, the
filtration plants also provide multiple barriers of public health protection, including chemical treatment, filtration and disinfection. Highly skilled operators at these plants must ensure that each process is
optimized. Finally, distribution system pipes and storage facilities must be in good repair to protect the water from re-contamination.
Can I have my water tested for Giardia and Cryptosporidium?
Several specialized laboratories in Pennsylvania are
capable of examining water samples for cysts and oocysts, but laboratory tests are very expensive for the private homeowner. Giardia cysts are extremely small; they are 10 times smaller than the smallest object that
can be seen with the naked eye, and Cryptospordium oocysts are even smaller. Although several hundred gallons of water must be examined, protozoan cysts may not be present at the place or time of sampling, or they
may even escape detection in the sample. Therefore, testing will not prove the absence of Giardia or Cryptosporidium; it can only prove the presence of such organisms. Furthermore, the test cannot accurately
determine the number of protozoa in a water supply or provide an assessment of potential infectivity.
What if I suspect or know that my water is contaminated?
A rapid boil of your drinking water for one full minute will destroy all Giardia cysts and Cryptosporidiumo ocysts. You should boil all water that you will use for drinking and cooking. A hot water heater may not kill all cysts, so as a precaution, use boiled water to wash vegetables or other food that requires washing. Also, because chlorine is ineffective against Cryptosporidium and must contact Giardia for at least 60 minutes in colder water, devices such as low temperature chemical sanitizers are not reliable for inactivating either organism.
As to washing clothing, it is unlikely that cysts or oocysts will be transferred from clothes to your mouth. Bathing is also safe in contaminated water, provided that the
water is not consumed. You should take special precautions when bathing small children and infants since they commonly ingest bath water. You should be careful not to use ice or brush your teeth with contaminated
water.
Several cartridge type filters, commonly called point-of-use filters, are currently available for household use, and some portable filters are available for backpackers,
campers and travelers. The manufacturers' data provided with these devices must explicitly state whether they are capable of removing cysts. The National Sanitation Foundation approves several point-of-use
devices capable of removing particles less than one micron in diameter (NSF Standard 42, Particulate Reduction, Class I), reverse osmosis filtration devices (NSF Standard 58), and cyst reduction devices (NSF
Standard 53); all of these will remove Giardia cysts and Cryptosporidium oocysts from drinking water. The installation and maintenance requirements of these devices must be strictly followed to ensure proper
operation. A word of caution is advised here because sales claims on point-of-use filters may not always provide the consumer with accurate information. Call your local Better Business Bureau or consumer protection agency to check for complaints against a particular product.
Also, bottled water permitted by the Department of Environmental Protection (DEP) originating from protected wells or springs is less likely to contain protozoan cysts.
DEP-permitted bottled water vending machines (in a supermarket, for example) approved by the National Automatic Merchandising Association and containing any of the above NSF-approved devices are considered safe;
however, consumers should use clean containers to prevent contamination.
What if I suspect that I have giardiasis or cryptosporidiosis?
During the illness, a physician can sometimes confirm giardiasis by examining stool samples
and accordingly prescribe medication to eliminate the Giardia parasite from the intestines. Some individuals will not be "cured" without the medication, although there is evidence that many people develop
resistance to giardiasis or even cure themselves. In other words, symptoms may subside without treatment, but if you have contracted giardiasis at some point in your life, you may be a carrier and infect others with
whom you have contact.
Although a physician can diagnose cryptosporidiosis in stool samples, a cure has not yet been found. Treatment of the symptoms is possible with antidiarrheal drugs, which
may lessen the severity in most healthy people. Like those with giardiasis, individuals with cryptosporidiosis may also cure themselves. Because cryptosporidiosis can be fatal in immune-compromised individuals, it
is extremely important to prevent an infection. Therefore, those with compromised immune systems may want to take additional precautions such as regularly boiling all tap water for drinking and cooking; avoiding
unpasteurized milk products; refraining from unsafe sex practices; and washing hands after using the toilet, after contact with infected people or animals, and before handling food.
What is being done to protect Pennsylvania residents from waterborne diseases?
The Department of Environmental Protection regularly conducts inspections at
Pennsylvania's public water systems to ensure that operators have the knowledge and equipment to optimize the performance of their facilities and protect public health. When a health risk is identified, all
municipal and private water suppliers immediately take steps to protect consumers, such as issuing boil water advisories or increasing chlorine doses. The supplier is then required to seek long-term alternatives,
such as a new source of water or a well-operated water treatment plant to remove the pathogens. DEP regulations require strict measures to filter all surface drinking water sources and to properly operate water
filtration plants. The department also evaluates and closely monitors surface-water filtration plants to ensure that Giardia and Cryptospordium are removed from the source water. In addition, the department has
initiated special training programs for many of Pennsylvania's small water system operators so they can do a better job of providing safe drinking water.
For More Information
You may contact the Laboratory. Cedar Grove will be glad to assist in your questions. Hoerver, if you wish to contact
the Pennsylvania Department of Environmental Resources immediately or directly, use the information below.
Pennsylvania Department of Environmental ResourcesContact:
Phil Consonery, Phone Number (717) 772-4018
Email CONSONERY.PHIL@a1.dep.state.pa.us
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