Why Is There Concern about Its

Presence in Drinking Water?

known to infect humans and many animal species. The

and infection can occur by consumption of contaminated

food or water, ingestion of contaminated recreational water,

or through contact with feces of infected persons or

both because it has become more widespread and

because of evidence that there are potential life-threatening

consequences of infection in the growing population of

This parasite is most often found in surface water,

although ground water can also be contaminated. Studies

have shown that up to 97% of U.S. surface waters may be

rains cause runoff of animal waste or when contaminated

wastewater is discharged by inefficient or improperly

operated wastewater treatment plants. Conventional water

treatment systems are not completely effective in removing

chlorine and filtration units can allow infectious oocysts to

The number of confirmed cases of cryptosporidiosis

attributable to drinking water contamination is low, largely

because of case underreporting by patients and by physicians.

Studies show that many physicians are unaware of

cryptosporidiosis and unfamiliar with its symptoms, and

The largest outbreak in U.S. history occurred in 1993 when

at least 400,000 people in Milwaukee became ill after drinking

54 deaths were attributed to the outbreak, primarily involving

results in a self-limiting diarrhea. Infection may result in

gastrointestinal illness after 2 to 10 days with watery diarrhea,

headache, abdominal cramps, nausea, vomiting, and lowgrade

fever. In healthy persons, symptoms normally disappear

within 1 to 2 weeks. However, persons with compromised

immune systems (e.g., persons with HIV/AIDS, cancer

patients, and transplant patients) may experience persistent

infection that may lead to severe, if not life-threatening,

intestinal tract, though the parasite has been found in the

lungs, liver, pancreas, bile ducts and gall bladder of AIDS

currently no established therapeutic drug for the treatment

of cryptosporidiosis, although paromomycin and

In 1999, the U.S. Environmental Protection Agency (EPA)

requirements for drinking water systems. More recently,

a Federal Advisory Committee recommended that EPA

treatment requirements in upcoming rules, to be

promulgated by May 2002.

be tested. Standard ova and parasite tests do not

specifically requested.

health department.

contracted and the symptoms of infection. Advise them

to wash hands with soap after using the toilet and before

handling food. Patients should also be advised to avoid

drinking water directly from lakes or rivers.

point of use filters may be appropriate. Patients should

look for filters labeled as “Absolute 1 micron” or a reverse

osmosis filter. To find out if a particular filter removes

independent testing and certification group (refer to

contact information provided below). Filters that are tested

and certified by NSF Standard 53 for cyst removal or cyst

According to EPA and CDC, heating water at a rolling boil

should be stored in a clean container with a lid and refrigerated.

standardized and often does not provide the consumer

with information needed to choose safe water. Individuals

should select a bottled water supplier only after careful

research. Bottled water treated by distillation or reverse

of waterborne disease, by becoming involved in local efforts

to prevent contamination of sources of drinking water. See

on how to become involved in these advocacy efforts.