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How does Cryptosporidium affect public health?

* Cryptosporidium is a microscopic parasite contained in an oocyst that breaks open and releases sporozoites once it enters the gastrointestinal tract. These sporozoites invade the GI tract lining. causing a disease known as Cryptosporidiosis, the chief symptom of which is acute watery diarrhea. There is no known cure other than treatment of the symptoms.

* One of the primary sources of Cryptosporidium is drinking water or contact with recreational waters contaminated by domestic and wild animal feces or human wastewater. Contact with infected animals or individuals is another possible pathway. It can infiltrate drinking water systems from source water contaminated by sewer overflows, wastewater plants and agricultural operations, as well as treatment plant breakdowns.

* Cryptosporidiosis more severely affects those with depressed immune systems, such as AIDS and cancer patients, the very young, or the elderly. However, in instances where drinking water supplies become contaminated, widespread effects may occur in the general population.

How Are Water Systems Kept Free of Cryptosporidium?

* Because of its ubiquity in animals, the presence of Cryptosporidium oocysts is widespread in surface water sources as well as in some groundwater sources.

* Unfortunately, this parasite is resistant to the traditional disinfection methods alone. Filtration in conjunction with ozonation and chlorine, plus chloramines, is generally effective in removing or destroying it if such treatment occurs before the water is released for distribution.

* Testing in watershed areas can detect the presence of Cryptosporidium and alert water treatment authorities to take necessary preventive measures. Particle and turbidity readings can be used to evaluate filtration.

* If the water supply becomes contaminated, boil-water advisories are required to prevent or minimize infection among the population.

How Is the Public Being Protected from Cryptosporidium Infection?

* Current approaches in monitoring do not guarantee protection from Cryptosporidium in drinking water. Health professionals, water treatment specialists, environmental experts, and government regulators have been examining methods to improve the prevention, detection, and treatment of Cryptosporidium in water sources. Cooperative efforts among these entities will enhance their ability to contain future outbreaks of Cryptosporidium related illness.

* Additional research is proceeding on the health effects of Cryptosporidium, which are still incompletely understood.

* The Environmental Protection Agency has proposed new regulations for water disinfectants and disinfectant by-products as well as for surface water treatment, in an attempt to improve monitoring, testing, and treatment for both chemical and microbial contaminants. More research and regulatory flexibility is being sought to balance the relative risks between these two threats to drinking water supplies.

* Drinking water suppliers are attempting to develop and implement the most effective detection and treatment methods for dealing with Cryptosporidium. Multi-barrier techniques, including source water protection, followed by filtration and disinfection in the treatment plant, plus a distribution system disinfectant residual, are considered the best approach.

Reprinted with permission from Drinking Water & Health, Vol. 2, Issue 3, Spring 1995.
COPYRIGHT 1995 National Environmental Health Association
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1995, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
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Publication:Journal of Environmental Health
Date:Sep 1, 1995
Previous Article:CDC, EPA issue drinking water guidance for people with weakened immune systems.
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