Environmental Engineering Reference
In-Depth Information
and 58 outbreaks, respectively. Untreated groundwater and treatment deficiencies
were the major causes.
56
Drinking water contaminated with sewage is the principal cause of water-
borne diseases. The diseases that usually come to mind in this connection are
bacterial and viral gastroenteritis, giardiasis, hepatitis A, shigellosis, and typhoid
and paratyphoid fevers. However, nearly one-half of outbreaks involving drink-
ing water in the United States between the years 1971 to 2002 were described
as gastroenteritis of unknown origin.
18
Protozoa, bacteria, and viruses were the
causative agents in 19, 14, and 8 percent of outbreaks, respectively, and chemicals
were responsible for 12 percent percent. A breakdown of the various diseases of
drinking water for eight decades in the United States can be found in Table 1.6.
16
Modern day globalization presents a concern for the monitoring and control
of infectious diseases. Human transport and interaction on an international scale
along with transport of animals and food items enhances the threat of disease
transmission. The United States must be vigilant in recognizing the risk for its
citizens in contracting infectious diseases or becoming carriers as a result of
travel to countries having lower standards of environmental health.
57
Because of the supervision given public water supplies and control over a
lessening number of typhoid carriers, the incidence of typhoid fever has been
reduced to a low residual level. Occasional outbreaks, due mostly to carriers,
remind us that the disease is still a potential threat. During the period 1967 - 1972,
Salmonella typhi
was isolated from 3661 individuals in the United States and,
coincidentally, the number of travel-associated cases of typhoid fever rose yearly
by 270%; a phenomenon believed connected in some way to Mexico.
57
Although
the incidence of typhoid fever cases has decreased from approximately 1.9 per
million to 1.3 per million travelers to Mexico between 1985 and 1994, of all
states reporting cases of typhoid fever to the Typhoid Fever Surveillance System
for the period between 1985 and 1994, California and Texas ranked one and two,
respectively, with California accounting for 44% of the 2443 cases recorded.
58
United States residents with Hispanic names were found to be at higher risk of
contracting typhoid fever than were others in the population.
57
In effect, glob-
alization is likely to influence the level of endemic infectious diseases in the
United States and, as noted by Mermin et al
58
, will be interconnected to the inci-
dence of infectious diseases in other countries of the world, thus underscoring
the importance of achieving high standards of environmental hygiene worldwide.
The outbreaks reported below are also instructive. In 1940 some 35,000 cases
of gastroenteritis and 6 cases of typhoid fever resulted when about 5 million
gallons of untreated, grossly polluted Genesee River water were accidentally
pumped into the Rochester, New York, public water supply distribution system.
A valved cross-connection between the public water supply and the polluted
Genesee River firefighting supply had been unintentionally opened. In order to
maintain the proper high pressure in the fire supply, the fire pumps were placed in
operation and hence river water entered the potable public water supply system.
The check valve was also inoperative.
