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Malaria
Katie Jeon
•
Malaria, one of the common diseases,
is caused by protozoan parasites of
the genus Plasmodium (phylum
Apicomplexa). In humans, malaria is
caused by P.falciparum, P.malariae,
P.ovale, and P.vivax. Malaria is
found in tropical and subtropical
climates, mostly Africa, South
America, the Middle East, India, and
all of the southeast Asia, because
Malaria-carrying mosquitoes,
Anopheles mosquitoes, require
temperatures of more than 68
degrees Fahrenheit. The Anopheles
mosquitoes actively multiply and
spread the disease in the rainy
season. In drier areas, outbreaks of
malaria can be predicted with
reasonable accuracy by mapping
rainfall.
Symptoms of Malaria
• The usual symptoms
characteristic of malaria
include flu-like illness with
fever, chills, muscle aches,
and headache. Some
patients develop nausea,
vomiting, cough, and diarrhea.
Cycles of chills, fever, and
sweating that repeat every
one, two, or three days are
typical. There can sometimes
be vomiting, diarrhea,
coughing, and yellowing
(jaundice) of the skin and
whites of the eyes due to
destruction of red blood
cells and liver cells.
• People with severe P.
falciparum malaria can
develop bleeding problems,
shock, liver or kidney
failure, central nervous
system problems, coma, and
can die from the infection
or its complications.
Cerebral malaria (coma, or
altered mental status or
seizures) can occur with
severe P. falciparum
infection. It is lethal if not
treated quickly; even with
treatment, about 15%-20%
die.
How is Malaria spread?
•
Malaria is transmitted to humans when an infected Anopheles mosquito
bites a person and injects the malaria parasites (sporozoites) into the
blood through the bloodstream to the liver, mature. Sporozioites in the
mosquito’s saliva enter the bloodstream and migrate to the liver.
Within 30 minutes of being introduced into the human host, they infect
the liver, multiplying asexually and asymptomatically for a period of 615days. They escape the liver into the blood and infect red blood cells.
Within the red blood cells, the parasites asexually multiply further and
periodically break out of their hosts to invade fresh red blood cells.
Usually, the parasite is relatively protected from attack by the body’s
immune system. However, the P.falciparum parasite displays adhesive
proteins on the surface of the infected blood cells, causing the blood
cells to stick to the walls of small blood, to avoid being destroyed in
the spleen. So the immune system can not destroy the red blood cell
surface adhesive proteins because of their extreme diversity. That is
why the P. falciparum is the most severe type among four Malarias.
Where the term comes from
• The term malaria originates
from Medieval Italian: mala
aria — "bad air" in 1740 by H.
Walpole when describing the
disease; and the disease was
formerly called ague or
marsh fever due to its
association with swamps. The
term was shortened to
"malaria" in the 20th century.
C. Laveran in 1880 was the
first to identify the
parasites in human blood.