Environmental Engineering Reference
In-Depth Information
therefore, would be expected to be of higher concentration in pipes of lower ele-
vation than those of higher elevation. Interestingly, in 1866 a cholera epidemic
occurred in the Whitechapel area of London that was traced to water supplied by
the East London Water Company whose source was the River Lea. William Farr
pronounced, “Only a very robust scientific witness would have dared to drink a
glass of the waters of the [river] Lea,” on which note Farr's notions that air, not
water, was the cause of London's infamous cholera epidemics came to an end.
42
Snow was immersed in the study of anesthesiaology in his final days and died
from complications of a stroke at the age of 45; quite possibly brought on by his
self-committed experimentation with chloroform, ether, and other noxious agents
in the quest for useful anesthetics. Epidemics of cholera persisted in London
after Snow's death. The poor water quality of the Thames is evident from the
account of a large pleasure craft that capsized on a Sunday afternoon in the mid
1800s with its passengers thrown into the river; no one drowned, but most died
of cholera within a few weeks, thereafter.
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In still another instance, Robert Koch (1843 - 1910), an eminent German physi-
cian, unaware of Pacini's earlier discovery, observed the cholera bacillus under
similar pathological conditions in Alexandria, Egypt, in 1883.
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In 1884, Koch
succeeded in isolating and culturing the organism from the stools of advanced
cholera patients in Calcutta, India. Closer to home in 1892, Koch investigated
the incidence of cholera in two adjacent cities in Germany that pumped drink-
ing water out of the Elbe River. Hamburg pumped water from a point upstream
and Altona, a suburb, took water downstream from the city sewer outfalls, but
the outbreak occurred in Hamburg upstream. However, the water in Altona was
filtered through a slow sand filter, whereas the water in Hamburg was not. Koch
isolated
Vibrio cholerae
from the polluted Elbe River, proving the relationship
between polluted water and disease. There were 8,605 deaths in Hamburg, a
death rate of 1,342 per 100,000. The death rate in Altona was 234 per 100,000.
Water treatment, specifically the application of a disinfectant, notably chlo-
rine, has practically eliminated cholera, typhoid, and dysentery in developed
areas of the world. The conquest of these and other waterborne diseases parallels
the development of microbiology and sanitary engineering, as well as immu-
nization; water treatment, including chlorination, proper excreta, and wastewater
disposal; and education in hygiene and public health. However, waterborne dis-
eases still occur with viral gastroenteritis (nonspecific gastroenteritis being more
common), infectious hepatitis A, giardiasis, and cryptosporidiosis. As noted else-
where, absence of potable water and latrines is associated with high diarrheal
illness and mortality rates among children under five in developing countries.
The major concerns in developed countries today are the chronic and degenera-
tive diseases, including those associated with the ingestion of trace amounts of
toxic organic and inorganic chemicals, but it is also essential that the safeguards
found effective in preventing waterborne diseases be maintained and strengthened
to prevent their recurrence.
Waterborne Disease Outbreaks
Given the vulnerability of surface waters
to pollution, it may be surprising to learn that in every decade since 1920,
