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25 April every year: Raising awareness of malaria as
a curable and preventable disease. The aim of World Malaria Day is to
provide education and understanding of malaria as a global scourge that
is preventable and a disease that is curable.
Malaria is caused by a parasite called Plasmodium. There are 5 species
of Plasmodium which infect humans:
Plasmodium vivax
Plasmodium falciparum
Plasmodium malariae
Plasmodium ovale
Plasmodium knowlesi which is less common.
Of these, Plasmodium falciparum infection is the most severe and can
cause death in up to 10% of cases. It can be rapidly fatal. Pregnant
women and children are especially at risk. Other types of malaria are
less severe, but still may cause death.
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How malaria is spread
The parasite is transmitted to humans by the bite of infected female
Anopheles species mosquitoes.
The parasites multiply in the liver and the bloodstream of the infected
person. The parasite may be taken up by another mosquito when it bites
an infected person. The mosquito is then infected for the duration of
its life and can infect other humans when it bites them.
Occasionally malaria is transmitted by blood transfusion. For this
reason, people who have travelled to countries where malaria occurs may
be deferred from giving blood for a short period. Malaria can also be
transmitted from a mother to her fetus.
Malaria occurs in most tropical and sub-tropical
areas of the world, including:
Africa
Central and South America
Asia (including southeast Asia)
Papua New Guinea
western Pacific islands.
Over 600,000 people living in these countries die from malaria each
year. Many thousands of tourists also get malaria during their travels
to countries where malaria is present. Tourists often get severe illness
because they have had no previous exposure to malaria and have no
resistance to the disease.
Signs and symptoms
Symptoms of malaria may include:
fever, which may come and go, or may be constant
chills
profuse sweating
malaise (feeling of unwellness)
muscle and joint pain
headache
confusion
nausea
loss of appetite
diarrhoea
abdominal pain
cough
anemia.
Plasmodium falciparum may cause cerebral malaria, a serious complication
resulting from inflammation of the brain that may cause coma.
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Diagnosis
Diagnosis is made by a blood test – sometimes it is necessary to repeat
the test a number of times, as the parasites can be difficult to detect.
Incubation period
(time between becoming infected and developing symptoms)
Varies with the type:
P. falciparum: 9 to 14 days
P . vivax: 12 to18 days but some strains may have an incubation period
of 8 to 10 months or longer
P. ovale: 12 to 18 days
P. malariae: 18 to 40 days
P. knowlesi 9 to 12 days.
These periods are approximate and may be longer if the person has been
taking drugs taken to prevent infection.
Infectious period
(time during which an infected person can infect others)
Direct person-to-person spread does not occur.
A person remains infectious to mosquitoes as long as the parasites are
present in the blood. This may be several years if adequate treatment is
not given. Parasites disappear from the blood within a few days of
commencing appropriate treatment. Mosquitoes remain infected for life.
Treatment
Specific antimalarial treatment is available and must always be started
as soon as malaria is diagnosed. There is increasing resistance to
currently available drugs and treatment should be carried out by an
infectious diseases specialist or other expert in the field.
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Prevention
Exclusion from childcare, preschool, school or work is not necessary but
cases should avoid being bitten by mosquitoes while they are unwell.
Travellers to areas with malaria are usually advised to take
preventative anti-malarial drugs.
There is no vaccine to prevent human infection by this parasite.
Personal protection and the environmental management of mosquitoes are
important in preventing illness. See Fight the Bite for tips to on how
to protect yourself.
Travel in countries where there is malaria
Extensive international programs are undertaken in malarious countries
to try to control this disease. For travellers, the following advice is
given:
See a travel medicine expert before you go to get specific advice for
the places you will be visiting.
Always take malaria prophylaxis drugs exactly as prescribed and take the
full course. Be aware of their potential side effects.
Protect yourself from mosquito bites. Travel medical centres have good
information on how to do this.
Be aware that no preventive measures are 100% effective, so always seek
medical attention immediately if you develop a fever while travelling
in, or after return from, a country where malaria occurs.
Always give your doctor the information about your travel if you become
sick.
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