Environmental Engineering Reference
In-Depth Information
between humans and the reservoir introduce the pathogen into human populations.
Wild animals and farm animals can be reservoirs for human disease.
To eliminate or reduce the incidence of insectbome diseases, it is necessary
to control the environment and reservoirs and the vectors. This would include
control of water and food, carriers of disease agents, and the protection of per-
sons and domestic animals from the disease (immunization). Where possible and
practical, the reservoirs and vectors of disease should be destroyed and the envi-
ronment made unfavorable for their propagation. Theoretically, the destruction
of one link in the chain of infection should be sufficient Actually, efforts should
be exerted simultaneously toward elimination and control of all the links, since
complete elimination of one link is rarely possible and protection against many
diseases is difficult, if not impossible, even under ideal conditions. The amount
of personnel, funds, and equipment available will frequently determine the action
taken to secure the maximum results or return on the investment made.
In developing countries, insecticide-treated bed nets have been distributed and
shown to effectively reduce malaria transmission. Including screens on windows
in the design of buildings is a relatively simple means of preventing mosquito
bites and disease transmission. In addition to such structural changes, preventative
anti-malarial medications are sometimes given to individual travelers venturing
from areas of no or low malarial endemnicity to areas of higher risk. However,
this intervention is not an option in parts of the world where malaria is endemic,
due to rapidly developing resistance to the drugs. In certain regions, a sleeping
adult may be bitten hundreds of times a night by mosquitoes; if even a small
proportion of the insects carry the malarial parasite, the risk of transmission
is high. Therefore, reducing mosquito populations can result in a decrease in
malarial transmission, as well as better quality of life.
Environmental Control of Infectious Diseases
Environmental interventions for preventing the spread of infectious diseases have
long been a central component of public health, with a storied history starting
long before the development of medications and vaccines. Malaria eradication in
North America was achieved largely through environmental interventions, such as
draining swamps and spraying insecticides. Large-scale engineering projects also
require public health support. The Panama Canal could not have been built without
research conducted by the military on protecting workers from yellow fever.
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Traditionally, clean drinking water (often referred to as
potable
water, water that
is clean enough, in terms of microorganisms and chemicals, that it could be used for
drinking), has been the primary concern of environmental and sanitary engineering,
in the realm of infectious disease transmission. Related to this is proper treatment
of sewage and other hazardous wastes. Water quality is covered in great detail in
Chapter 4. However, there are other areas of environmental engineering that can
play a crucial role in preventing the spread of infectious diseases.
The International Rice Research Institute (IRRI), based in the Philippines, has
conducted extensive research into implementable environmentally oriented prac-
tices for reducing malaria transmission in developing countries. Since mosquitoes
