The following
are responses and summaries of various readings related to Human Health,
Disease, and the Environment.
Six Modern Plagues, Chapter
5: A Spring to Die For: Hantavirus
Hantavirus
pulmonary syndrome is a disease that has existed in the American Southwest
since, at the very least, the time of Columbus’s exploration. It invades the lungs of its victim and causes
them to drown in their own fluid. The
disease is transmitted by the urine or saliva of mice. When there is a great increase in the mouse
population of the area there is a proportionate increase in the number of
Hantavirus cases. This was especially
the case when in 1993 there was a great outbreak of the virus which has since
been attributed to the recent heavy rains caused by El Nino. Though the Navajo had knowledge of the
disease for centuries before, what emerged for the rest of Americans was “a
powerfully new, encompassing view of humans not as a stand-alone species but as
just one species among many in a web of climate, ecology, and intertwined
fates.” The spring of 1993, just as the
months before previous outbreaks, had seen a huge explosion of the mouse
population in nearby rural areas. The
abundance of mice thereafter ventured into the cities and residential areas
where the spread the disease to humans.
Chapter 6: A Virus from the Nile
For the
northern house mosquito, Culex pipiens, a
native of the mid Northeastern Atlantic United States, a drought is
heaven. After feeding the female
mosquito leaves her eggs in sewage, because sewage is teeming with nutrients. Birds are mosquitos’ prey of choice, though
they do occasionally feed on humans and other animals as well. With each new victim the virus(es) contained
within the mosquitoes’ bodies has a chance to move from the mosquito to a new
host. By a process known as
amplification the virus can, using mosquitoes as vectors, spread rapidly and
take root in millions of birds. August
and September of 1999 saw New York City receive its first cases of West Nile
Virus, but months before the first human cases it was obvious that something
was amok as hundreds of crows and other birds began turning up dead without
apparent explanation. Though many people
believed that the drought had directly caused the deaths, it would not have
done so in a controlled environment like the local zoo where captive birds fell
prey.
The
summer of 1998 was unusually hot in Israel, where thousands of white storks fly
through during their migration from Europe to Africa every year. This excess heat caused many of them to make
more lengthy stays than usual in the eastern Mediterranean nation. It is believed that these birds were the
reason for the reintroduction of West Nile Virus back into the ecosystem
there. It is then believed that either
an infected bird, mosquito, or human carried the virus to the United States and
likely to Kennedy Airport near Queens, New York. In only three years the virus had managed to
make its way all across the continental U.S. to California, with hundreds of
dead people and thousands of birds in its path.
Epilogue: SARS and Beyond
According
to the people who study epidemics it is only a matter of time until the next
great pandemic. Therefore it was not
really surprising when SARS, the severe acute respiratory syndrome, took off so
quickly in 2002. It was the first
disease to appear in the new century with epidemic possibilities. Most recently HIV/AIDS, Ebola hemorrhagic
fever, Lyme disease were the disease with outbreak potential. SARS began in Guangdong Province, China in
November 2002. It causes headaches,
muscle soreness, and dry coughs that quickly become pneumonia. China managed to keep the outbreak under
wraps until a man a doctor who had been in Guangdong traveled to Hong Kong
where he caused the infection of many other people of different
origination. The virus then spread with
its new hosts all throughout Southeast Asia but most surprisingly attached to a
Canadian couple who then infected hundreds in the Toronto area; dozens
died. Today contagious disease is able
to quickly spread across the globe due to the vast amount of daily
international travel and the global black market.
It
is believed that SARS evolved from a disease which previously afflicted another
species. There are two ways a virus, or
bacteria, may evolve. It can merge with
the genetic material of another organism or achieve a spontaneous genetic
mutation. Of the billions of possible
random mutations very few are actually beneficial. In the case of SARS, a mutation which was
beneficial to the virus, i.e. allowing it to infect humans, was the
result.
Life Support, Chapter 6: Global Climate Change and Health
The
global temperature is constantly increasing.
It appears that there are more and more greenhouse gases in the
atmosphere which are trapping additional amounts of heat within the surface of
the Earth causing the planet to heat.
Mans combustion of fossil fuels, destruction of the world’s forests,
irrigated agriculture, animal breeding, and manufacturing of cement seem to be
the primary causes of these gases. This
all pinnacled in the 1990s, the hottest decade in the last 1000 years. The global temperature is expected to rise
1.4 to 5.8 degrees C in the next 100 years.
Due to this violent and previously rare weather events like drought,
floods, and storms are going to become more likely and occur much more often
than before. This can be seen with El
Nino, which since the mid 70s has increased in frequency, magnitude and
duration.
The
change in climate is the perfect breeding ground for the growth of previously
controlled diseases. Cases of malaria and dengue fever are ever increasing in
Africa, Asia, and Latin America. Change
in climate will increase vector-borne disease, intestinal infections, and death
and injury caused by extreme weather events.
There will also be and increased
rate of death from familiar causes as well as the emergence of new infectious
diseases. Studies have shown the viral
maturation rates increase with an increase in temperature.
Readings above may have been drawn from the
following sources:
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