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MALARIA
ILYSSA FISHER
For several years, I have had an interest in virology and the
spread and characteristics of various infectious diseases. Though it
makes sense not to possibly induce a state of panic by informing
individuals of illnesses that are not native to the area they live in
and that they are not likely to contract, I have always liked to
remain informed out of my own curiosity and interest. Thus, I have
decided to write about malaria.
Malaria kills more people than any communicable disease except for
tuberculosis. It is caused by four species of parasitic protozoa that
infect human red blood cells. Four different types of these protozoa
are known: protozoa falciparum, protozoa vivax, protozoa ovale, and
protozoa malariae. Protozoa falciparum is the most lethal of the four
and accounts for the majority of infections. Malaria parasites are
not able to survive unless they have both a mosquito and human host,
however the disease cannot be hosted by any kind of mosquito, only
those of the genus "anopheles".
Malaria is spread when the mosquito picks up the parasites from the
blood of an infected human when it feeds. The mosquito will first
recieve the malaria parasite from feeding on the blood of a person
who may not neccessarily show symptoms of the disease, but has the
parasites in their bloodstream. When the mosquito feeds again, these
parasites will be passed on to another human being. Symptoms of
malaria include fever, shivering, pain in the joints, headache,
repeated vomiting, generalized convulsions, and coma. If not treated,
the disease, especially that caused by protozoa falciparum, will
progress to severe malaria. Severe malaria generally results in
death.
Approximately 90% of of the world's malaria cases occur in
sub-Saharan Africa, including in high altitude areas such as Kenya's
highlands that were previously thought to have elevations too high
for the transmission of the disease. Malaria, however, is not unique
to Africa. There are a multitude of documented cases in Asia
annually, particularly in countries such as India, Bangladesh,
Vietnam, and Cambodia. Malaria has also been known to occur in
portions of Iran and the Middle East. Lower altitude regions of South
and Central America also have their share of annual malaria cases,
but control programs set up in those regions typically keep things
under control. Generally, North America, Europe, and the Carribean
have been highly successful in the control and elimination of
malaria, although isolated, rare cases of local transmission have
occured in Haiti, Turkey, and the Dominican Republic.
Medical treatment for malaria is available and the disease is curable
if promptly diagnosed and treated well. This is crucial because those
who have malaria parasites available for mosquitoes to feed on are
perpetuating the spread of the disease. However, if these people are
treated with the appropriate drugs, the parasites disappear from
their bloodstream. This helps to reduce the transmission of the
disease. Unfortunately, not everyone is responsive to drug treatments
for malaria and thus a variety of alternatives need to be available.
Not everyone with malaria parasites in their bloodstream shows the
symptoms of malaria and the disease itself is becoming resistant to
some of the drugs used to treat it.
Fortunately, there are also many non-medical options in the control
and treatment of malaria. Some methods have included the screening of
dwellings to prevent infected misquitos from entering the home, the
introduction of mosquito-eating fish to more bodies of water, and
surrounding beds with incesticide-treated netting. Anything which
reduces the likelyhood of mosquito presence can help.
One of the most highly successful methods for malaria control has
been DDT, a compound used to treat the walls of dwellings in areas
with high rates of malaria infection. DDT has been in use in malaria
control programs since the 1940's and has proved generally effective.
The most common use of DDT in preventing the spread of malaria is to
spray the backs of chairs and walls of a dwelling with the substance
to keep out adult mosquitos who enter the dwelling to feed on those
who live there. Though DDT treatments are still an effective way to
stop the spread of malaria, some mosquitos have become resistant to
the compound and therefore more methods of prevention must be
utilized.
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