Malaria
Classification and external resources
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 Plasmodium falciparum ring-forms and gametocytes in human blood. |
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Malaria is a mosquito-borne infectious
disease caused by a eukaryotic protist of the
genus Plasmodium. It is
widespread in tropical and
subtropical regions, including parts of the Americas (22
countries), Asia, and Africa. Each year,
there are more than 250 million cases of malaria,[1] killing
between one and three million people, the majority of whom are young children
in sub-Saharan
Africa.[2] Ninety
percent of malaria-related deaths occur in sub-Saharan Africa. Malaria is
commonly associated with poverty, and can indeed be a cause of poverty[3] and a major
hindrance to economic
development.
Five species
of the plasmodium parasite can infect humans: the most serious forms of the
disease are caused by Plasmodium falciparum. Malaria
caused by Plasmodium vivax, Plasmodium
ovale and Plasmodium
malariae causes milder disease in humans that is not generally fatal. A fifth
species, Plasmodium
knowlesi, is a zoonosis that causes
malaria in macaques but can
also infect humans.[4][5]
Malaria is
naturally transmitted by the bite of a female Anopheles mosquito. When a
mosquito bites an infected person, a small amount of blood is taken, which
contains malaria parasites. These develop within the mosquito, and about one
week later, when the mosquito takes its next blood meal, the parasites are
injected with the mosquito's saliva into the person being bitten. After a
period of between two weeks and several months (occasionally years) spent in
the liver, the malaria parasites start to multiply within red blood cells, causing
symptoms that include fever, and headache. In severe
cases the disease worsens leading to hallucinations, coma, and death.
A wide
variety of antimalarial
drugs are
available to treat malaria. In the last 5 years, treatment of P. falciparum
infections in endemic countries
has been transformed by the use of combinations of drugs containing an artemisinin derivative.
Severe malaria is treated with intravenous or intramuscular quinine or, increasingly,
the artemisinin derivative
artesunate.[6] Several
drugs are also available to prevent malaria in travellers to malaria-endemic countries (prophylaxis).
Resistance has developed to several antimalarial drugs, most notably chloroquine.[7]
Malaria
transmission can be reduced by preventing mosquito bites by distribution of
inexpensive mosquito nets and insect
repellents, or by mosquito-control measures such as spraying insecticides inside
houses and draining standing water where mosquitoes lay their eggs.
Although many are under development, the challenge
of producing a widely available vaccine that provides a high level of protection for a
sustained period is still to be met. - Friskila Damaris Silitonga, SKEP, NS, MPH
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