ATLANTA- The Centers for Disease Control and Prevention
has released a statement advising people who are immunocompromised to consider
alternatives to untreated tap water. The CDC action, based on concern about
contamination with the Cryptosporidium parasite, marks the first time any
Federal government agency has issued such a blanket water quality warning.
The CDC advisory comes on the heels of a report from the Natural Resources
Defense Council (NRDC) which concluded that more than 45 million Americans
drink water from plants that have been contaminated with cryptosporidium.
The cryptosporidium protozoan was responsible for a mass outbreak of disease
that affected more than 400,000 people and killed over 100 in Milwaukee.
Another cryptosporidium outbreak has been linked to the deaths of 35 HIV-infected
individuals in Las Vegas.
A joint study by the CDC and the Environmental Protection Agency found
that more than half of the public water supplies that obtain raw water from
rivers, lakes, and streams have low levels of Cryptosporidium in the treated,
filtered water.
The parasite causes a variety of gastrointestinal symptoms in otherwise
healthy individuals who become infected, including diarrhea, cramps, fatigue,
nausea, and vomiting. Symptoms usually develop from five to ten days after
ingesting the oocysts. In people with impaired immune systems, infection
with cryptosporidium can cause severe, potentially fatal disease. There
is no effective treatment for the infection in immunocompromised patients.
The CDC advisory is principally aimed at people with compromised immune
systems including people with HIV infection and AIDS; those undergoing treatment
for cancer; and recipients of organ transplants. They are advised to consider
boiling municipal water, drinking bottled water or using certain microstraining
filters as a precaution against becoming exposed to the waterborne parasite.
According to the agency, bottled water from protected wells and springs,
properly monitored, and bottled water from municipal sources that have been
distilled or subject to reverse osmosis or to one micron absolute filtration
provide consumers reasonable assurance of the absence of cryptosporidium.
Cryptosporidium found in the feces of infected humans or young animals.
Infection can occur upon contact with oocysts, either by drinking contaminated
water or handling contaminated materials or touching people or animals that
have come into contact with the organism. The cyst is not killed by disinfectants
such as chlorination treatment, which is used by most water utilities.
"Only filtration systems capable of removing contaminants one micrometer
or less in diameter are effective in removing the cyst. Also, consumers
should carefully follow all manufacturers' instructions for proper product
use and maintenance," said Joseph Harrison, chief technical director
for the Water Quality Association (WQA) and a member of a CDC working group
on cryptosporidium and filtration systems.
These filtration systems are the only ones currently considered effective
at protecting against ingesting water borne cryptosporidium from drinking
water when used consistently at home and at work, he emphasized.
While drinking water appears to be the main source of infection in the
population at large, the organisms can also be contracted in polluted rivers
and lakes as well as in public swimming pools. A new as yet unpublished
study by the CDC suggests the organism can also be spread by sexual contact
or diaper changing, according to Dr. Dennis Juranek, parasitic diseases
division, CDC.
The Environmental Protection Agency is expected to enact new regulations
in December 1995 that will require a utility serving 10,000-plus people
to test its source water for cryptosporidium. Utilities will be required
to test the finished or treated water to determine if the cyst is being
removed during the treatment process, if initial tests reveal contamination
with cryptosporidium.
For information about water treatment and filtration systems, write the
Water Quality Association at WQA National Headquarters and Laboratory, 4151
Naperville Rd., Lisle, Ill., 60532, or call the EPA Safe Drinking Water
Hotline at 800-426-4791.
The CDC issued its warning in the 6/15/95 issue of its newsletter, the
Morbidity and Mortality Weekly Report.
