P H Y S I C I A N S F O R S O C I A L R E S P O N S I B I L I T Y
D R I N K I N G W A T E R F A C T S H E E T # 13
What Health Care Providers Should Know
Contaminants Cause Diarrhea?
A wide variety of waterborne viruses, bacteria, and parasites
can cause acute diarrhea. These include Cryptosporidia,
Salmonella, Shigella, Campylobacter jejuni, rotavirus, E. coli
O157:H7 and other pathogenic E. coli species, Giardia, and
the caliciviruses (i.e., Norwalk and Norwalk-like viruses).
Much of the time, the etiology of waterborne disease
outbreaks in the U.S. is unknown. In most cases, it is thought
that the illness is viral in nature, most likely caused by
caliciviruses (1,2). The reported cases of waterborne disease
probably represent only a small fraction of the outbreaks
that actually occur in the U.S. every year. It is very difficult
to connect individual cases of gastroenteritis, and most
waterborne diseases are not tracked by the Centers for
Disease Control and Prevention (2). Typical stool sampling
does not include many common pathogens, such as
Cryptosporidium, and viral agents are often difficult to detect
in clinical samples (2). See PSR’s fact sheets on Cryptosporidium
and E. coli for more information.
Who is Most Susceptible to Diarrhea Caused
by Contaminants in Drinking Water?
In the U.S. and other developed countries, drinking water
disinfection has dramatically reduced gastrointestinal infections
from such waterborne pathogens as cholera and typhoid.
However, waterborne disease still occurs, usually because of
a breach in the water treatment system or because pathogens
that are insensitive to disinfection, like Cryptosporidia, enter
the water supply. Certain populations are at greater risk of
diarrheal disease from waterborne pathogens. These include
the elderly, infants and young children, and individuals with
severely weakened immune systems, such as AIDS patients,
patients undergoing certain types of chemotherapy, and those
who have recently received organ tran