papers may help remind everyone of the need for care-
ful monitoring of food preparation.
Some foods meant to be eaten raw or briefly
cooked, such as fruit or rare beef, do carry a small risk.
Consumers should realize that food is not sterile, that
meat, for example, is contaminated with the animals’
intestinal bacteria during slaughtering. Meat should
be thoroughly cooked. Fruit and vegetables should be
washed or peeled before being eaten raw. (Food-borne
diseases, also called food poisoning, are included in
the tables of diseases that appear at the end of this
chapter.)
Finally, the safety of our food may depend on some-
thing we often take for granted: our refrigerators. For
example, a Thanksgiving turkey that was carved for
dinner at 3 P.M. and left on the kitchen counter until
midnight probably should not be used for turkey sand-
wiches the next day. Although we have to rely on oth-
ers to ensure that commercially prepared food will be
safe, once food reaches our homes, all we really need
(besides the refrigerator) is our common sense.
Water
When we turn on a faucet to get a glass of water, we
usually do not wonder whether the water is safe to
drink. It usually is. Having a reliable supply of clean
drinking water depends on two things: diverting
human sewage away from water supplies and chlori-
nating water intended for human consumption.
Large cities have sewer systems for the collection of
wastewater and its subsequent treatment in sewage
plants. Once treated, however, the sludge (solid, par-
ticulate matter) from these plants must be disposed of.
This is becoming more of a problem simply because
there is so much sewage sludge (because there are so
many of us). Although the sludge is largely free of
pathogens, it ought not to be put in landfills, and
because ocean dumping is being prohibited in many
coastal areas, this is a problem that will be with us for
a long time.
Drinking water for cities and towns is usually chlo-
rinated. The added chlorine kills virtually all bacteria
that may be present. The importance of chlorination
is shown by a 1978 outbreak of enteritis (diarrhea)
in a Vermont town of 10,000 people. The chlorina-
tion process malfunctioned for 2 days, and 2000 of the
town’s inhabitants became ill. (The bacterium
was Campylobacter, a common intestinal inhabitant of
animals.)
You may now be wondering if all those bottled
spring waters are safe to drink. The answer, in general,
is yes, because the bottling companies do not wish to
make people ill and put themselves out of business.
Some bottled waters, however, do have higher mold
spore counts than does chlorinated tap water. Usually
these molds are not harmful when ingested; they are
destroyed by the hydrochloric acid in gastric juice.
In much of North America, nearly everyone has
easy access to safe drinking water. We might remind
ourselves once in a while that our water will not give
us typhoid, dysentery, or cholera. These diseases are
still very common in other parts of the world, where
the nearest river or stream is the laundry, the sewer,
and the source of drinking water. The World Health
Organization (WHO) estimates that more than 2.5
billion people do not have basic sanitation, and more
than 1 billion do not have dependable access to clean
water to drink.Emerging Diseases
and Biological Weapons
The term emerging diseasesmay be a bit misleading,
because some of the pathogens are not really new.
What has happened is that we have become aware of
them. A good example of this is Lyme disease. Lyme
disease in the United States was named for the town in
Connecticut where a cluster of cases was discovered in
the 1970s. When the causative bacteria were later
found and the disease fully characterized, health offi-
cials realized that the disease had been described in
Scandinavia in the early years of the 20th century.
Lyme disease was not a new disease after all, merely a
newly encountered disease for Americans.
Other emerging diseases are those caused by the
Ebola and Marburg viruses, by Hantavirus, West Nile
virus, and the SARS (severe acute respiratory syn-
drome) virus, by certain strains of E. coli, and by antibi-
otic-resistant strains of enterococci. The tasks of public
health officials are to keep track of all cases of these
diseases and to educate medical personnel about them.
Anthrax is no longer in the news, as it was in the
autumn of 2001 when spores were sent through the
U.S. mail. As of 2006, no other instances of the use of
biological weapons have been reported, though use of
the smallpox virus as a weapon remains a concern.
Public health officials had hoped that improvements
to public health policies and procedures that were
spurred by the use of anthrax as a weapon would not506 An Introduction to Microbiology and Human Disease