Page 384 - Environment: The Science Behind the Stories

We are fighting disease with diverse
approaches

We have many ways to fight disease, but one of the most effec-
tive is to improve the basic living conditions of the world’s poor.
Besides providing food security (p. 264), this means ensuring
access to safe drinking water and improving sanitation by min-
imizing exposure to human waste, garbage, and wastewater. In
recent years, we have made slow but steady progress in provid-
ing adequate drinking water and sanitation to the world’s peo-
ple (Figure 14.6), which helps reduce the incidence of diseases,
such as cholera and dysentery, that are spread through drinking
water contaminated with human or animal feces.
Another important pursuit is to expand access to health
care. In developing nations, this includes opening clinics,
immunizing children against diseases, providing prenatal and
Figure 14.5 Disease can spread rapidly in our highly mobile, postnatal care for mothers and babies, and making generic and
internationalized world. The H1N1 swine flu outbreak in 2009–2010 inexpensive pharmaceuticals available.
showed how a strain of a fast-evolving infectious disease can Education campaigns play a vital role in rich and poor
quickly spread around the globe. As of 2013, over 18,000 people nations alike. Public service announcements and government
had died of this flu.

whose pathogens evolve rapidly, give rise to a variety of
strains, making it more likely that one may turn exceedingly 100
dangerous and threaten a global pandemic.
In addition to natural strains of diseases, there is growing 80
concern over bioterrorism, the intentional genetic manipula-
tion of a pathogenic organism to increase its virulence and/ 60
or transmission between humans. This issue received atten- Percent of population 40
tion in 2012 when, after much debate in the scientific com-
munity and security agencies, the journal Nature published a 20
study describing how scientists genetically engineered a strain
of H5N1 avian flu to make it more transmissible through the 0
air. Critics argued that the journal article provided a “recipe” 1990 1995 2000 2005 2010 2015
for creating a bioterror weapon, but supporters contended the (projected)
information would help governments track and better contain Year
virulent strains of H5N1 by providing information about the (a) Proportion of global population with access to improved
genetic factors in the virus that promote airborne transmission. drinking water
The changes we cause to our environment can also cause
diseases to spread. Human-induced global warming (Chapter 18) 100
is causing tropical diseases such as malaria, dengue, cholera,
and yellow fever to begin expanding into the temperate zones. 80
And habitat alteration can affect the abundance, distribution,
and movement of certain disease vectors. 60
To predict and prevent infectious disease, environmental Percent of population
health experts assess the complicated relationships among tech- 40 CHAPTER 14 • Envi R onm E n TA l H EA lTH A nd T o xi C ology
nology, land use, and ecology. Malaria, an infectious disease that 20
claims an estimated 650,000 lives each year, provides an exam-
ple. The microscopic protists (four species of Plasmodium) that 0
cause malaria depend on mosquitoes as a vector. These protists 1990 1995 2000 2005 2010 2015
can sexually reproduce only within a mosquito, and it is the mos- (projected)
quito that injects the protists into a human or other host. Thus, Year
the primary mode to control malaria has been to use insecticides (b) Proportion of global population with access to improved
such as dichlorodiphenyl-trichloroethane (DDT) to kill mosqui- sanitation
toes. People using insecticides and draining wetlands in broad- Figure 14.6 We are gradually providing access to sanitation
scale eradication projects have eliminated malaria from large and clean drinking water for the world’s people. The percent-
areas of the temperate world where it used to occur, such as the age of the global population with access to clean or “improved”
southern United States. However, human land disturbance that drinking water (a) and sanitary facilities (b) has increased in recent
creates pools of standing water in formerly well-drained areas decades. Data from World Health Organization, 2012. World health statistics
can boost mosquito populations and allow malaria to reinvade. 2012. WHO, Geneva, Switzerland. 383

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