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BACKGROUND REPORT MARCH 19, 2009
Malaria
Malaria is a parasitic disease
transmitted between humans by the bite of an infected Anopheles mosquito.
The disease causes flu-like symptoms and attacks of fever and chills.
Malaria is curable, but if
left untreated it disrupts the blood supply to vital organs and becomes
deadly.
Malaria has been virtually eradicated in countries with temperate climates,
but is still prevalent in tropical and subtropical countries. About
40 percent of the world's population lives in areas where there is
a risk of contracting malaria.
Each year there are about 250
million malaria cases and 880,000 deaths, according to World Health
Organization statistics. It is particularly deadly for children in Africa,
where one in every five childhood deaths is caused by malaria.
Beyond the human toll, malaria
wreaks significant economic havoc where it is prevalent, decreasing
gross domestic product by as much as 1.3 percent in countries with high
levels of transmission.
When a mosquito bites a person infected with malaria, it ingests a form
of the parasite, which then completes part of its life cycle inside
the mosquito and moves to the bug's salivary glands. When the now-infected
mosquito bites another human, it injects the parasite into the bloodstream.
In humans, the parasites migrate
to the liver, where they mature and release another form of parasites
that enter the bloodstream and infect red blood cells, multiplying inside
and rupturing the blood cells.
The classic symptoms of malaria are fever, chills, sweating, headaches
and muscles pains. Other symptoms of malaria can include vomiting and
diarrhea. Severe complications can include cerebral malaria, anemia
from the destruction of red blood cells or liver and kidney failure.
Malaria becomes life-threatening by disrupting the supply of blood to
vital organs.
There is currently no effective
vaccine for malaria. In countries where the disease is endemic, malaria
prevention methods are focused on reducing transmission of the disease
by the parasite infected mosquitoes. The two main interventions are
indoor residual spraying of the walls of homes with insecticides, and
the use of insecticide-treated mosquito nets, a cost-effective method
of protecting people while they sleep.
Other methods of control include
reducing standing water where mosquitoes could breed.
Most of the malaria medications used to treat the disease can also be
used to prevent it. Anti-malaria medications can provide some protection,
and travelers to countries with known malaria problems often take preventive
courses of malaria drugs. but people on the medications can still
become infected. Parasite resistance to commonly used anti-malaria drugs
has spread quickly, complicating efforts to prevent and treat the disease.
Early diagnosis and prompt treatment can shorten the duration of the
malaria infection and prevent further complications and a majority of
deaths.
The most used medications to fight malaria attack the parasites in the
blood. They include chloroquine, sulfadoxine-pyrimethamine, mefloquine,
atovaquone-proguanil (Malarone), quinine, doxycycline and artemisin
derivatives.
The spread of parasitic resistance to some of the most conventional
and affordable malaria drugs, such as chloroquine and sulfadoxine-pyrimethamine,
has undermined efforts to control the disease.
The best available treatment for malaria, according to the World Health
Organization, is a combination of drugs called artemisinin-based combination
therapies, or ACTs. There is little documented resistance to artemisinins.
When used in combination with other drugs, they can slow the development
of resistance to those drugs as well.
Sources: The World Health Organization,
the CDC, the Mayo Clinic, National Institute of Health and U.S. National
Library of Medicine.
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