|
Usually,
people get malaria by being bitten by an infected
female Anopheles mosquito. Only Anopheles mosquitoes
can transmit malaria and they must have been infected
through a previous blood meal taken on an infected
person.
When a mosquito
bites, a small amount of blood is taken in which
contains the microscopic malaria parasites. The
parasite grows and matures in the mosquito's gut
for a week or more, then travels to the mosquito's
salivary glands. When the mosquito next takes
a blood meal, these parasites mix with the saliva
and are injected into the bite.
Once in the blood,
the parasites travel to the liver and enter liver
cells to grow and multiply. During this "incubation
period", the infected person has no symptoms.
After as few as 8 days or as long as several months,
the parasites leave the liver cells and enter
red blood cells. Once in the cells, they continue
to grow and multiply. After they mature, the infected
red blood cells rupture, freeing the parasites
to attack and enter other red blood cells. Toxins
released when the red cells burst are what cause
the typical fever, chills, and flu-like malaria
symptoms.
If a mosquito bites
this infected person and ingests certain types
of malaria parasites ("gametocytes"),
the cycle of transmission continues.
Because the malaria
parasite is found in red blood cells, malaria
can also be transmitted through blood transfusion,
organ transplant, or the shared use of needles
or syringes contaminated with blood. Malaria may
also be transmitted from a mother to her fetus
before or during delivery ("congenital"
malaria).
Malaria is
not transmitted from person to person like a cold
or the flu. You cannot get malaria from casual
contact with malaria-infected people.
|