Cryptosporidium: the public concern
CRYPTOSPORIDIOSIS (krip-to-spo-rid-e-ó-sis) (Fact Sheet)
CRYPTOSPORIDIUM (UK)
CRYPTOSPORIDIUM - FREQUENTLY ASKED QUESTIONS
Drinking Water Contamination by Dumps and Landfills
Volatile Organic Chemical Contaminants

Volatile Organic Chemical Contaminants

Following is a brief description of the volatile organic contaminates regulated in Florida.

 

Benzene

This chemical is used as a solvent and degreaser of metals. It is also a major component of gasoline. Drinking water contamination generally results from leaking underground gasoline and petroleum tanks or improper waste disposal. This chemical has been associated with significantly increased risks of leukemia among certain industrial workers who were exposed to relatively large amounts of this chemical during their working careers. This chemical has also been shown to cause cancer in laboratory animals when the animals are exposed at high levels over their lifetimes. Chemicals that cause increased risk of cancer among exposed industrial workers and in laboratory animals also may increase the risk of cancer in humans who are exposed at lower levels over long periods of time. The enforceable drinking water standard for benzene has been set by DEP at 0.001 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in humans and laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

Carbon tetrachloride (Tetrachloromethane)

This chemical was once a popular household cleaning fluid. It generally gets into drinking water by improper waste disposal. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed at lower levels over long periods of time. The enforceable drinking water standard for carbon tetrachloride has been set by DEP at 0.003 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

Dichloromethane

This organic chemical is a widely used solvent. It is used in the manufacture of paint remover, as a metal degreaser and as an aerosol propellant. It generally gets into drinking water after improper discharge of waste disposal. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed over long periods of time. EPA has set the drinking water standard for dichloromethane at 0.005 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe with respect to dichloromethane.

 

Ortho-dichlorobenzene

This organic chemical is used as a solvent in the production of pesticides and dyes. It generally gets into water by improper waste disposal. This has been shown to damage the liver, kidneys and the blood cells of laboratory animals such as rats and mice exposed to high levels during their lifetimes. Some industrial workers who were exposed to relatively large amounts of this chemical during working careers also suffered damage to the liver, nervous system, and circulatory system. EPA has set the drinking water standard for o-dichlorobenzene at 0.6 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to o-dichlorobenzene.

 

Para-dichlorobenzene

This chemical is a component of deodorizers, moth balls and pesticides. It generally gets into drinking water by improper waste disposal. This chemical has been shown to cause liver and kidney damage in laboratory animals such as rats and mice when the animals are exposed to high levels over their lifetimes. Chemicals which cause adverse effects in laboratory animals also may cause adverse health effects in humans who are exposed at lower levels over long periods of time. EPA has set the enforceable drinking water standard for para-dichlorobenzene at 0.075 part per million (ppm) to reduce the risk of these adverse health effects which have been observed in laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

1,2-Dichloroethane

This chemical is used as a cleaning fluid for fats, oils, waxes, and resins. It generally gets into drinking water from improper waste disposal. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed at lower levels over long periods of time. The enforceable drinking water standard for l,2-dichloroethane has been set by DEP at 0.003 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

1,1-Dichloroethylene (l,l-Dichloroethene)

This chemical is used in industry and is found in drinking water as a result of the breakdown of related solvents. The solvents are used as cleaners and degreasers of metals and generally get into drinking water by improper waste disposal. This chemical has been shown to cause liver and kidney damage in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals which cause adverse effects in laboratory animals also may cause adverse health effects in humans who are exposed at lower levels over long periods of time. EPA has set the enforceable drinking water standard for l,l-dichloroethene at 0.007 part per million (ppm) to reduce the risk of these adverse health effects which have been observed in laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

Cis-1,2-Dichloroethylene

This organic chemical is used as a solvent and intermediate in chemical production. It generally gets into water by improper waste disposal. This chemical has been shown to damage the liver, nervous system, and circulatory system of laboratory animals such as rats and mice when exposed at high levels over their lifetimes. Some humans who were exposed to relatively large amounts of this chemical also suffered damage to the nervous system. EPA has set the drinking water standard for cis-1,2-dichloroethylene at 0.07 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water which meets the EPA standard is associated with little to none of this risk and is considered safe with respect to cis-1,2-dichloroethylene.

 

Trans-1,2-Dichloroethylene

This organic chemical is used as a solvent and intermediate in chemical production. It generally gets into water by improper waste disposal. This chemical has been shown to damage the liver, nervous system, and the circulatory system of laboratory animals such as rats and mice when exposed at high levels over their lifetimes. Some humans who were exposed to relatively large amounts of this chemical also suffered damage to the nervous system. EPA has set drinking water standard for trans-1,2-dichloroethylene at 0.1 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to trans-1,2-dichloroethylene.

 

1,2-Dichloropropane

This organic chemical is used as a solvent and pesticide. When soil and climatic conditions are favorable, 1,2-dichloropropane may get into drinking water by run-off into surface water or by leaching into ground water. It may also get into drinking water through improper waste disposal. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed over long periods of time. EPA has set the drinking water standard for 1,2-dichloropropane at 0.005 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to 1,2-dichloropropane.

 

Ethylbenzene

This organic chemical is a major component of gasoline. It generally gets into water by improper waste disposal or leaking gasoline tanks. This chemical has been shown to damage the kidneys, liver, and nervous system of laboratory animals such as rats exposed to high levels during their lifetimes. EPA has set the drinking water standard for ethylbenzene at 0.7 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to ethylbenzene.

 

Monochlorobenzene

This organic chemical is used as a solvent. It generally gets into water by improper waste disposal. This chemical has been shown to damage the liver, kidneys and nervous system of laboratory animals such as rats and mice exposed to high levels during their lifetimes. EPA has set the drinking water standard for monochlorobenzene at 0.1 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to monochlorobenzene.

 

Styrene

This organic chemical is commonly used to make plastics and is sometimes a component of resins used for drinking water treatment. Styrene may get into drinking water from improper waste disposal. This chemical has been shown to damage the liver and nervous system in laboratory animals when exposed at high levels during their lifetimes. EPA has set the drinking water standard for styrene at 0.1 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to styrene.

 

Tetrachloroethylene

This organic chemical has been a popular solvent, particularly for dry cleaning. It generally gets into drinking water by improper waste disposal. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed over long periods of time. DEP has set the drinking water standard for tetrachloroethylene at 0.003 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. Drinking water that meets this standard is associated with little to none of this risk and is considered safe with respect to tetrachloroethylene.

 

Toluene

This organic chemical is used as a solvent and in the manufacture of gasoline for airplanes. It generally gets into water by improper waste disposal or leaking underground storage tanks. This chemical has been shown to damage the kidneys, nervous system, and circulatory system of laboratory animals such as rats and mice exposed to high levels during their lifetimes. Some industrial workers who were exposed to relatively large amounts of this chemical during working careers also suffered damage to the liver, kidneys and nervous system. EPA has set the drinking water standard for toluene at 1 part per million (ppm) to protect against the risk of adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to toluene.

 

1,2,4-Trichlorobenzene

This organic chemical is used as a dye carrier and as a precursor in herbicide manufacture. It generally gets into drinking water by discharges from industrial activities. This chemical has been shown to cause damage to several organs, including the adrenal glands. EPA has set the drinking water standard for 1,2,4-trichlorobenzene at 0.07 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water which meets the EPA standard is associated with little to none of this risk and should be considered safe with respect to 1,2,4-trichlorobenzene.

 

1,1,1-Trichloroethane

This chemical is used as a cleaner and degreaser of metals. It generally gets into drinking water by improper waste disposal. This chemical has been shown to damage the liver, nervous system and circulatory system of laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Some industrial workers who were exposed to relatively large amounts of this chemical during their working careers also suffered damage to the liver, nervous system and circulatory system. Chemicals which cause adverse effects among exposed industrial workers and in laboratory animals also may cause adverse health effects in humans who are exposed at lower levels over long periods of time. EPA has set the enforceable drinking water standard for l,l,l-trichloroethane has been set at 0.2 part per million (ppm) to protect against the risk of these adverse health effects which have been observed in humans and laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

1,1,2-Trichloroethane

This organic chemical is an intermediate in the production of 1,1,-dichloroethylene. It generally gets into water by industrial discharge of wastes. This chemical has been shown to damage the kidneys and liver of laboratory animals such as rats exposed to high levels during their lifetimes. EPA has set the drinking water standard for 1,1,2-trichloroethane at 0.005 part per million (ppm) to protect against the risk of these adverse health effects. Drinking water which meets the EPA standard is associated with little to none of this risk and should be considered safe with respect to 1,1,2-trichloroethane.

 

Trichloroethylene (Trichloroethene)

This chemical is a common metal cleaning and dry cleaning fluid. It generally gets into drinking water by improper waste disposal. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed at lower levels over long periods of time. The enforceable drinking water standard for trichloroethene has been set by DEP at 0.003 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

 

Vinyl chloride

This chemical is used in industry and is found in drinking water as a result of the breakdown of related solvents. The solvents are used as cleaners and degreasers of metals and generally get into drinking water by improper waste disposal. This chemical has been associated with significantly increased risks of cancer among certain industrial workers who were exposed to relatively large amounts of this chemical during their working careers. This chemical has also been shown to cause cancer in laboratory animals when the animals are exposed at high levels over their lifetimes. Chemicals that cause increased risk of cancer among exposed industrial workers and in laboratory animals also may increase the risk of cancer in humans who are exposed at lower levels over long periods of time. The enforceable drinking water standard for vinyl chloride has been set by DEP at 0.001 part per million (ppm) to reduce the risk of cancer or other adverse health effects which have been observed in humans and laboratory animals. Drinking water which meets this standard is associated with little to none of this risk and should be considered safe.

Xylenes

These organic chemicals are used in the manufacture of gasoline for airplanes and as solvents for pesticides, and as cleaners and degreasers of metals. They usually get into water by improper waste disposal. These chemicals have been shown to damage the liver, kidneys and nervous system of laboratory animals such as rats and dogs exposed to high levels during their lifetimes. Some humans who were exposed to relatively large amounts of these chemicals also suffered damage to the nervous system. EPA has set the drinking water standard for xylenes at 10 parts per million (ppm) to protect against the risk of these adverse health effects. Drinking water that meets the EPA standard is associated with little to none of this risk and is considered safe with respect to xylenes. 

Drinking Water Contamination by Dumps and Landfills

Dumps and landfills are not entirely synonymous and a distinction should be made. A dump is defined as, " a site used to dispose of solid wastes without environmental controls." (4). The term 'landfill' is replacing 'dump' due to the modernization of our solid waste facilities. Landfill is defined as a "facility in which solid waste from municipal and/or industrial sources is disposed; sanitary landfills are those that are operated in accordance with environmental protection standards." (2) This distinction is very important because it allows us to distinguish between two different eras and practices. Even so, some modernized landfills are poorly engineered or located in an environmentally unsound areas. The upgrade of waste disposal sites from dumps to environmentally sound solid waste disposal systems was mandated by a set of hazardous waste amendments passed in 1986. Landfills are now regulated at one of three class levels depending on the nature of solid or hazardous waste accepted.

Well designed landfills should not cause water quality problems because leachate problems are anticipated and controlled.  Return to the top

CRYPTOSPORIDIUM - FREQUENTLY ASKED QUESTIONS 

Q What is Cryptosporidium and how is it transmitted?
A Cryptosporidium is a microscopic parasite that is found in the feces of infected humans or animals. Humans are infected when they ingest contaminated water or food, or touch contaminated objects, then touch their mouth before washing their hands well. Cryptospoidiosis, the disease caused by Crytosporidium, is a common cause of diarrhea among people with AIDS. 

Q What are the symptoms? 
A Symptoms of Cryptosporidium infection in persons with normal immune systems include diarrhea that lasts one to two weeks, often accompanied by abdominal cramps, fatigue, nausea, vomiting, and low-grade fever. People usually develop symptoms two to 10 days after ingesting the parasite. In persons with weakened immune systems, Cryptosporidiosis can be chronic and life threatening. 

Q Who is at risk for severe Cryptosporidiosis? 
A People at risk for severe Cryptosporidiosis include people with AIDS, people who have cancer, or organ or bone marrow or transplant patients who are taking drugs that suppress the immune system, and people who are born with genetically weakened immune systems. 

Q Why is Cryptosporidium a problem in drinking water? 
A Cryptosporidium is a problem because most water from lakes, rivers and streams contain some of the microscopic parasite. Most communities get their water from these "surface" sources, rather than from underground sources such as wells. Cryptosporidium is highly resistant to chlorine and other disinfectants, which are used to kill bacteria and viruses in drinking water. In addition, Cryptosporidium is so small that the type of filters used in conventional municipal water treatment does not easily remove it from the water. 
Over half of the tested public water supplies that use surface water have been found to have small amounts of Cryptosporidium in the water sent to homes and businesses. 

Q How can I tell if there is Cryptosporidium in my drinking water? 
A You cannot tell without expensive, special tests. These tests are not very good for home use, and are not always reliable. 

Q Is there a cure for Cryptosporidium infection? 
A No. Some drugs, such as paromomycin (Par-o-mo-my-sin), may reduce the symptoms of Cryptosporiodosis, but no drug now known can cure it. Diarrhea can cause dehydration. People with diarrhea should contact their health care provider who may recommend an oral rehydration therapy mix. 

Q Should I take extra protective measures? 
A It depends on your health and your drinking water. If you have AIDS, if you have cancer or if you have had an organ or bone marrow transplant and are taking drugs that weaken your immune system, or if you were born with a genetically weakened immune system, you may want to take extra measures. You should talk to your health care provider regarding the level of your risk and on how to reduce it. 
If you have a healthy immune system, you are at less risk for Cryptosporidiosis, but you may want to consider the quality of your drinking water. Unfortunately, assessing the risk of Cryptosporidium infection from your drinking water is not easy. Tests for Cryptosporidium in public water supplies are not easy to interpret. A positive test does not necessarily mean there is a risk, and a negative test does not necessarily mean there is no risk. If your drinking water comes from surface source (lake, stream, river) that is unfiltered, or one that is located downstream from a sewage treatment facility or runoff from farming, your water may be at increased risk of containing Cryptosporidium. Q What can immuno-suppressed people do to avoid infection with Cryptosporidium? A Avoid sexual practices that may result in exposure to feces. 
Avoid drinking water directly from lakes, rivers, ponds or streams. 
Avoid swimming in lakes, rivers, streams, ponds, public swimming pools or recreational parks. 
Avoid working with diaper-aged children. 
Avoid contact with feces of all animals, particularly young farm animals such as calves. Always wash hands thoroughly: 

• after any contact with animals; 
• after any contact with soil (e.g. gardening); 
• after changing diapers; and 
• before eating, or preparing food. 

Q Can I take a shower or bath? 
A Yes, but avoid swallowing any water. 

Q Can I use ice cubes already frozen?
A No. Discard all ice cubes because they may contain Cryptosporidium. Make new ice cubes with boiled, filtered or bottled water. 

Q Can I brush my teeth with tap water? 
A No. Use boiled, filtered or bottled water. 

Q Is drinking water the only source of the parasite that causes Cryptosporidiosis? 
A No, there are many other sources. For example, foods, such as unwashed fruits and vegetables, especially from a foreign country, swimming pools, recreational water and pets are common sources. (day care centres, nursing homes mentioned) 
Q I have a filter on my tap. Is my water safe to drink? 
A Not all available home water filters remove Cryptosporidium. Look for labels that say:

• Reverse osmosis treated
• Filtered through an absolute 1 micron or smaller filter
• 1 micron absolute
• NSF Standard 53 certified for cyst removal/reduction

• Water processed by method effective against Cryptosporidium
• Reverse Osmosis Treated
• Filtered through an absolute 1 micron or smaller filter
• Distilled
• "1 micron absolute" 

So what is the public concern about? Cryptosporidium means 'hidden spore'; transmitted readily by water systems, the organism is named after the ease with which it can escape detection in samples. Without a cure, it has earned a worldwide reputation as a serious threat to public health. 

First detected in Europe only as recently as the 1980s, Cryptosporidium has often struck communities, which had until then enjoyed safe water with apparently high standards of filtration. In 1987, Cryptosporidium hit Carrollton, a university town in rural Georgia, USA. Thirteen thousand people out of a total population of 65,000, many of them students, fell ill with diarrhoea, stomach cramps and vomiting. The authorities discovered that every household on the water supply system received contaminated water, yet the town's filtration system complied fully with national filtration standards. In 1993 the City of Milwaukee, Wisconsin, suffered on an even bigger scale. 400,000 residents fell ill through contamination of the water system with four thousand residents hospitalised at an estimated cost of $54 million. There have also been over a dozen outbreaks reported in the United Kingdom. 

What worries health authorities is Cryptosporidium's resistance to many traditional treatments including chlorination, rendering much of the treatment process irrelevant. A single-celled organism, it has many attributes of the 'nightmare bug' -it is difficult to detect, able to live for long periods in cold dark reservoirs and pipes, strikes large numbers of people and presents a threat to life for the elderly, very young and immuno-compromised. 

It is unclear how it is able to survive chlorination although it is believed that its protective 'oocyst' membrane plays a role. One theory is that the organism might use a pump mechanism to expel toxins from its inside before they cause it harm. Whatever its defence, it is effective: a study by the US Environmental Protection Agency suggested that Cryptosporidium could even live on Chlorine products. 

Although difficult to detect it is still relatively rare in most well maintained public water systems. The greatest danger is to people who use private water supplies. These supplies are, of course, tested. Research* in the United Kingdom suggests effective screening requires very frequent analysis of water samples. With less advanced filtration systems in private water supplies, the organism is able to pass easily, often escaping detection by hiding in the biofilm of the water system. 

By 1992 cases of Cryptosporidium in the United States had reached the same level as those of Giardia, until then the most common microbial contaminant in water supplies. Cases in Europe also increased. With Cryptosporidium's apparent resistance to disinfection and its ability to slip through any but the best kept filtration systems, the onus is on health agencies and water suppliers to invest in effective detection systems. As a contaminant of the water supply, the organism has the potential to infect large numbers of people particularly where water supplies serve densely populated urban areas. It is the scale of potential harm that puts Cryptosporidium in the first league of emerging pathogens. 

Cryptosporidium in Water Supplies 
Cryptosporidium is a very small protozoan parasite of the Coccidia genus. It has a worldwide distribution and is found in a large number of hosts including birds, fish and mammals. The organism can cause an unpleasant, self-limiting, gastrointestinal illness in humans. Two thirds of people who contract the illness (Cryptosporidiosis) are children. 

The 1989, in the United Kingdom, an outbreak in Swindon was the first time the country's public health authorities became aware of the potential scale of the problem. Cryptosporidium is excreted in huge numbers and is capable of surviving for long periods in the environment. It can also be passed on as a secondary infection as it requires a low infective dose of less than 100 organisms. The volume of water sample required to screen the water supply has to be large, often as much as 20 litres. With such a small number of organisms diffused in a large volume of water, it is easy to see how the organisms escape detection. 

Health Action
Following the first series of major outbreaks, governments and their water suppliers had to find answers to many questions. Most research since however, has not provided simple answers. Tests have shown that source protection allied to attention to detail during treatment is the best method to reduce Cryptosporidium numbers in supply water. There is no known safe level for treated water and no health related standard for water quality looks forthcoming. 

Private Water Supplies 
This is where the greatest risks lie. Many private water supplies have little source protection and no treatment. What treatment is available is genera>

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What is cryptosporidiosis?

 Cryptosporidiosis is a disease caused by the parasite Cryptosporidium parvum, which as late as 1976 was not known to cause disease in humans. Until 1993, when over 400,000 people in Milwaukee, Wisconsin, became ill with diarrhea after drinking water contaminated with the parasite, few people had heard of either cryptosporidiosis or the single-celled intestinal protozoon that causes it.

Since the Milwaukee outbreak, concern about the safety of drinking water in the United States has increased, and new attention has been focused on determining and reducing the risk for cryptosporidiosis from community and municipal water supplies.

How is cryptosporidiosis spread?

 Cryptosporidiosis is spread by putting something in the mouth that has been contaminated with the stool of an infected person or animal. In this way, people swallow the Cryptosporidium parasite, which is too small to be seen with the naked eye. A person can become infected by drinking contaminated water or eating raw or undercooked food contaminated with Cryptosporidium oocysts (an egg-like form of the parasite that is the infectious stage); direct contact with the droppings of infected animals or stool of infected humans; or hand-to-mouth transfer of oocysts from surfaces that may have become contaminated with microscopic amounts of stool from an infected person or animal.

What are the symptoms of cryptosporidiosis?

 Two to ten days after infection by the parasite, symptoms may appear. Although some persons may not have symptoms, others have watery diarrhea, headache, abdominal cramps, nausea, vomiting, and low-grade fever. These symptoms may lead to weight loss and dehydration.

In otherwise healthy persons, these symptoms usually last 1 to 2 weeks, at which time the immune system is able to stop the infection. In persons with suppressed immune systems, such as persons who have AIDS or recently have had an organ or bone marrow transplant, the infection may continue and become life-threatening.

What should you do if you suspect that you have cryptosporidiosis?

 See your physician. Since the routine stool examination used for most parasites usually fails to detect Cryptosporidium, a stool specimen should be examined using stains/tests available especially for this parasite. It is important for persons with a poorly functioning immune system to seek medical attention early in the course of their disease.

What is the treatment for cryptosporidiosis?

 No safe and effective cure is available for cryptosporidiosis.

 People who have normal immune systems improve without taking antibiotic or antiparasitic medications.

 The treatment recommended for this diarrheal illness is to drink plenty of fluids and to get extra rest. Physicians may prescribe medication to slow the diarrhea during recovery.

Who is at risk?

 Persons at increased risk for cryptosporidiosis include child care workers; diaper-aged children who attend child care centers; persons exposed to human feces by sexual contact; and caregivers who might come in direct contact with feces while caring for a person infected with cryptosporidiosis at home or in a medical facility. Once infected, persons with suppressed immune systems, such as cancer chemotherapy patients, are at risk for severe disease.

How can you prevent cryptosporidiosis?

• Avoid water or food that may be contaminated.
• Wash hands after using the toilet and before handling food.
• If you work in a child care center where you change diapers, be sure to wash your hands thoroughly with plenty of soap and warm water after every diaper change, even if you wear gloves.

HIV-infected persons should avoid drinking water directly from lakes or rivers; avoid unpasteurized milk or milk products; avoid exposure to calves and lambs and places where these animals are raised; wash hands after contact with pets; and wash hands after gardening or other contact with soil. Because any sexual activity that brings a person in contact with the feces of an infected partner greatly increases the risk for cryptosporidiosis, HIV-infected persons and AIDS patients should follow safer sex guidelines and avoid sexual practices that may result in contact with feces.

If you are a caregiver of cryptosporidiosis patients, wash hands after bathing patients, emptying bedpans, changing soiled linen, or otherwise coming in contact with the stools of patients.

If you have cryptosporidiosis, wash your hands often to prevent spreading the disease to other members of your household.
 
 

For more information on cryptosporidiosis, see the following sources:

Cordell RL, Addiss DG. Cryptosporidiosis in child care settings: a review of the literature and recommendations for prevention and control. Pediatr Infect Dis J. 1994;13(4):310-7.

Dubey JP, Speer CA, Fayer R. Cryptosporidiosis of man and animals. Boston: CRC Press, 1990.

LeChevallier MW, Norton WD, Lee RG. Giardia and Cryptosporidium spp. in filtered drinking water supplies. Appl Environ Microbiol 1991;57(9):2617-21.

MacKenzie WR, Hoxie NJ, Proctor ME, Gradus MS, Blair KA, Peterson DE, Kazmierczak JJ, Addiss DG, Fox KR, Rose JB, Davis JP. A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the filtered public water supply. N Engl J Med 1994; 331:161-7.

Rose JB, Gerba CP, and Jakubowski W. Survey of potable water supplies for Cryptosporidium and Giardia. Environmental Science and Technology 1991;25(8):1393-1400.

Smith PD, Quinn TC, Strober W, Janoff EN, Masur H. Gastrointestinal infections in AIDS. Ann Intern Med 1992;116:63-77.

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SUMMARY

The oocysts are usually transmitted by contaminated water, infected animals, person-to-person spread or contaminated food (C.parvum requires a host to multiply in, and cannot grow in foods or water). Water treatment plants cannot usually guarantee to remove all C.parvum from water because the oocysts are very small and resistant to chlorine. At pres>

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BACKGROUND

The organism was discovered early in the twentieth century but its importance was only realised in the 1970s by veterinary workers investigating the causes of scours in young farm animals. Many of the early human cases were noted in the 1980s as serious infections in severely immunocompromised patients including AIDS sufferers Now widely recognised as an enteric pathogen with a world-wide distribution, it is endemic in some areas. Infection rates are highest in developing countries and in children. Many animal species can be infected and C.parvum is readily passed from animals to humans. 

CRYPTOSPORIDIOSIS

Mature oocysts are excreted in faeces. Excretion may stop fairly promptly after the cessation of diarrhoea or it may continue at low levels for some weeks even after all symptoms of illness have gone. 

The parasite is transmitted by the faecal oral route and infection may be acquired in a number of ways: 

-- from contaminated water
-- from animals, particularly lambs and calves, but also pets
-- from person to person contact
-- from contaminated raw foods, e.g. raw meat, unpasteurised milk, fruit and vegetables 

Farmyard manure may contain high numbers of cryptosporidial oocysts and consequently water may be contaminated by manure or slurry washed off fields into rivers; vegetable crops may be contaminated by direct manuring of the fields in which they are grown. Well managed and stored manure and slurry is effective in reducing infectivity through raised temperature and ammonia levels. 

OUTBREAKS

The largest recognised outbreak was in Milwaukee USA in l993 when it was estimated that some 400,000 people may have been affected by contaminated drinking water In the UK there have been several outbreaks associated with farm visits and some well-publicised water-borne outbreaks. There were about 500 confirmed cases in the Spring of 1989 in the Swindon area; a contaminated reservoir was implicated. In the Summer of 1995 there were over 500 confirmed cases in Devon and drinking water was the suspected source. 

LIFE CYCLE

Oocysts mostly sporulate within the gut and two types are produced. The thin-walled type releases more sporozoites in the gut (auto infection) and the thick-walled types are excreted in faeces in a fully infective form. They do not need any further maturation, unlike many other Coccidian protozoa. 

RESISTANCE OF OOCYSTS

Oocysts are remarkably resistant to many common disinfectants, including chlorine-based compounds Very high concentrations of disinfectant may be effective, but such levels are not practical for water treatment. 

WATER TREATMENT

In view of this, both English and American public health authorities have recently (1995) advised severely immunocompromised people to boil drinking water in order to reduce the chance of acquiring waterborne cryptosporidiosis. (Bottled water is not guaranteed free of C.parvum) . It is sufficient simply to bring water to the boil to eliminate C.parvum. 

It should be stressed that to be effective the guidance must be followed consistently for all water used for drinking or for washing foods intended for consumption without cooking. 

FOOD

There is a potential danger that infected food handlers could contaminate food; people with symptoms must not handle foods and advice should be taken on when they can restart such work (usually at least 48 hours after symptoms resolve). Personal hygiene is very important with this illness because the infective dose is so low. 

DETECTION

Organisms in water samples can be concentrated by filtration followed by centrifugation. Deposits are then usually examined microscopically and immunofluorescent methods are now available. Newer methods include concentration by flocculation and detection by flow cytometry prior to microscopic examination. 

Identification of viable and non-viable oocysts from environmental and faecal samples relies upon direct microscopy and differential staining techniques, but this requires considerable expertise. Cryptosporidiosis is diagnosed after oocysts have bean detected in faecal samples. ELISA methods may be used for serodiagnosis. 

Further reading

DoE DOH, Cryptosporidium in Water Supplies, Second Report of the Group of Experts, HMSO, 1995, ISBN 0 11 753136 7 

DoE DoH, Cryptosporidium in Water Supplies, HMSO, 1990, ISBN 0 11 75Z322 4

Glossary

Oocyst: an encysted zygote. 

Sporozoite: a motile cell produced in the oocyst by mitotic division. 

Merozoite: a motile, uninucleate cell arising from asexual division. 

The Institute of Food Science & Technology (IFST) is the independent professional qualifying body for food scientists and technologists. It is totally independent of government, of industry, and of any lobbying groups or special interest groups. Its professional members are elected by virtue of their academic qualifications and their relevant experience, and their signed undertaking to comply with the Institute's ethical Code of Professional Conduct. They are elected solely in their personal capacities and in no way representing organisations where they may be employed. They work in a variety of areas, including universities and other centres of higher education , research institutions, food and related industries, consultancy, food law enforcement authorities, and in government departments and agencies. The nature of the Institute and the mixture of these backgrounds on the working groups drafting IFST Position Statements, and on the two Committees responsible for finalising and approving them, ensure that the contents are entirely objective. 

IFST recognises that research is constantly bringing new knowledge. However, collectively the profession is the repository of existing knowledge in its field. It includes researchers expanding the boundaries of knowledge and experts seeking to apply it for the public benefit. 

Its purposes are 

1. to serve the public interest by furthering the application of science and technology to all aspects of the supply of safe, wholesome, nutritious and attractive food, nationally and internationally; 
2. to advance the standing of food science and technology, both as a subject and as a profession; 
3. to assist members in their career and personal development within the profession; 
4. to uphold professional standards of competence and integrity.