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Malaria

Malaria


Malaria parasites have been with us since the beginning of time, and
fossils of mosquitoes up to thirty million years old show that malaria's vector
has existed for just as long.   The parasites causing malaria are highly specific,
with man as the only host and mosquitoes as the only vector.   Every year,
300,000,000 people are affected by malaria, and while less than one percent of
these people die, there are still an estimated 1,500,000 deaths per year.   While
Malaria was one of the first infectious diseases to be treated successfully with
a drug, scientist are still looking for a cure or at least a vaccination today
(Cann, 1996).   Though many people are aware that malaria is a disease, they are
unaware that it is life threatening, kills over a million people each year, and
is a very elusive target for antimalarial drugs (Treatment of Malaria, 1996).
Being a very specific disease, malaria is caused by only four protozoal
parasites:   Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and
Plasmodium malariae.   Not only is the disease specific, but the parasites are
too, with only 60 of 380 species of female Anopheles mosquitoes as vectors.
With the exception of Plasmodia Malariae which may affect other primates, all
parasites of malaria have only one host, Homo sapiens.   Because some mosquitoes
contain substances toxic to Plasmodium in their cells, not all species of
mosquitoes are vectors of Plasmodium.   Although very specific, malaria still
causes disruption of over three hundred million people worldwide each year (Cann,
1996).
The life cycle of the parasite causing malaria exists between two
organisms, humans and the Anopheles mosquito.   When a female mosquito bites a
human, she injects an anticoagulant saliva which keeps the human bleeding and
ensures an even flowing meal for her.   When the vector injects her saliva into
the human, it also injects ten percent of her sporozoite load.   Once in the
bloodstream, the Plasmodium travel to the liver...