"Crypto" Detected, Hazards Studied

Researchers and water quality regulators are paying increased attention to cryptosporidium, a potentially deadly parasite commonly occurring in untreated surface water. Cryptosporidium, nicknamed "crypto," recently attracted attention in Arizona when the parasite was found in Phoenix's and Mesa's treated drinking water supplies.

The Phoenix water department found minute specimens of crypto in tests at two water-treatment plants during the past three months. Follow-up tests of the same batch of water found no traces of the parasite. State officials say the slight traces are no cause for alarm.

The low level occurrence of crypto reported in Arizona does not pose the serious health hazard that the occurrence of the parasite did in Milwaukee and Las Vegas. Crypto killed 100 people and left hundreds of thousands sick in Milwaukee, and last year it contributed to the deaths of 19 AIDS patients in Las Vegas.

Even low-levels are a cause for concern, however. Chuck Gerba of the University of Arizona's Department of Soil and Water Science, says, "At those low levels you probably are not going to see an outbreak. But you may get low-level transmission throughout the community. And so it has to be looked at more from that standpoint." Gerba's UA lab developed the first method for detecting crypto in water.

Arizona Department of Health Services spokesman Jeff Davis said no cases of cryptosporidiosis have been reported in Arizona this year. Seven unrelated cases were reported last year, with four in Maricopa County, and one each in Pima, Apache and Yavapai counties.

Gerba questions the accuracy of such reports providing statistics of numbers infected by the parasite. "They say there were only three cases in Phoenix last year. But, in reality, only six people may have been tested all year."

The effects of crypto at this level are difficult to trace because of the diseases's rather lengthy incubation period of seven days. Few cases, therefore, are properly diagnosed. Most infected people assume their nausea and diarrhea are from something they ate the day before.

The parasite comes from the feces of wild and domestic animals and is found in up to 87 percent of untreated water supplies. Rain runoff carries the parasite to surface water supplies. Gerba estimates that crypto is in about one third of the country's finished drinking water supplies.

The parasite causes severe diarrhea and nausea. Healthy individuals recover in about 10 days, but the virus can be deadly for children, the elderly or anyone with a weak immune system, such as those affected by AIDS.

Phoenix and Mesa are testing for crypto even though it is not required. A rule scheduled to go into effect next year will require water utilities servicing more than 10,000 to sample their raw water. If a certain level of crypto is detected, then they are to sample their finished water for 18 months.

The EPA once thought only heavily contaminated water threatened human health. In a recent New England Journal of Medicine, however, researchers from the University of Texas reported that crypto is far more infectious that previously thought.

In response to the NEJM article, Carol Browner, EPA administrator, called for further research on the parasite and ways of detecting it. She mentioned that Congress is scheduled to vote later this year on the reauthorization of the Safe Drinking Water Act, amid speculation the law will be made less restrictive.