|
How People Get Malaria (Transmission)
How is
malaria transmitted?
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.
I live in
the United States, where there is no malaria. Can I still get
malaria?
You will
be most at risk if you travel to countries where malaria is
endemic ("malaria-risk areas"). However, a few cases of
malaria occur every year in the United States in people who
have not left the country. Fortunately, these are very rare
occurrences. Malaria may be transmitted through blood
transfusions, organ transplants, shared use of needle or
syringes, or by local transmission (see
Introduced malaria
above). A few cases of congenital malaria are reported each
year; infected mothers pass the parasite to their fetus during
pregnancy or delivery. Malaria remains a public health concern
in the United States even though the disease has been
eradicated in this country.
|