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Malaria
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The Impact of Malaria, a Leading Cause of Death Worldwide
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On This Page:
Statistics | Geography | Who
Is Most Vulnerable | How Malaria Affects People's
Health | Areas Where Malaria Is
Not Endemic | Social And
Economic Toll
Statistics
Malaria is
one of the most severe public health problems worldwide. It is a leading
cause of death and disease
in many developing countries, where young children and pregnant women
are the groups most affected.
Leading
Causes of Death in Children Under Five Years of Age, Estimates
for 2000-2003
(Source:
World Health Organization, The World Health Report 2005)
|
Rank |
Cause |
Numbers
(thousands per year)
|
%
of all deaths
|
1
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Neonatal causes |
3,910
|
37
|
2
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Acute respiratory infections |
2,027
|
19
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3
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Diarrheal
diseases |
1,762
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17
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4
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Malaria |
853
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8
|
5
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Measles |
395
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4
|
6
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HIV/AIDS |
321
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3
|
7
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Injuries |
305
|
3
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Other
causes |
1,022
|
10
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Total |
10,596
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100.0
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According to the World Health Organization’s World
Malaria Report 2005:
- At the end of 2004, some 3.2 billion people lived in areas
at risk of malaria transmission in 107 countries and territories.
- Between 350 and 500 million clinical episodes of malaria occur every
year.
- At least one million deaths occur every year due to malaria.
- About
60% of the cases of malaria worldwide and more than 80% of the malaria
deaths worldwide occur in Africa south of the Sahara.
more:
Statistics and Malaria's Public Health Impact
Geography
Malaria occurs
mostly in poor, tropical and subtropical areas of the world (Geographic
Distribution). The area most affected is Africa south of the Sahara,
where an estimated 90% of the deaths due to malaria occur. This is due
to a combination of factors:
- A very
efficient mosquito vector (Anopheles gambiae) assures high transmission
- The predominant
parasite species is Plasmodium falciparum, which causes the most
severe form of malaria
- Local
weather conditions often allow transmission to occur year round
- Scarce
resources and socio-economic instability hinder efficient malaria control
activities.
In
other areas of the world malaria is a less prominent cause of deaths,
but can cause substantial disease and incapacitation, especially in rural
areas of some countries in South America and Southeast Asia.
Who
Is
Most Vulnerable
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Pregnant woman having a blood smear taken at an antenatal clinic at the Maela Camp in Thailand near the Myanmar border. Pregnant women are at increased risk of malaria. Image contributed by the Shoklo Malaria Research Unit, Mae Sot, Thailand.
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Persons most
vulnerable are those with no or little protective immunity against the
disease. In areas with high transmission (such as Africa south of the
Sahara), the most vulnerable groups are:
- Young
children, who have not yet developed immunity to malaria
- Pregnant
women, whose immunity is decreased by pregnancy, especially during
the first and second pregnancies
- Travelers
or migrants coming from areas with little or no malaria transmission,
who lack immunity.
In areas
with lower transmission (such as Latin America and Asia), residents are
less frequently infected. Many persons may reach adult age without having
built protective immunity and are thus susceptible to the disease.
How
Malaria Affects People's Health
Malaria
can affect a person's health in various ways.
- People
who have developed protective immunity (through past infections, as
is the case with most adults in high transmission areas) may be infected
but not made ill by the parasites they carry
- In
most cases, malaria causes fever, chills, headache, muscle ache, vomiting,
malaise and other flu-like symptoms, which can be very incapacitating
- Some
persons infected with Plasmodium falciparum can develop complications
such as brain disease (cerebral malaria), severe anemia, and kidney
failure. These severe forms occur more frequently in people with little
protective immunity, and can result in death or life-long neurologic
impairment
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Child
being transfused in Kinshasa, DR Congo. Malaria is the principal
cause of severe anemia, necessitating transfusion, in children
in DR Congo.
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- People
subjected to frequent malaria infections (such as young children and
pregnant women in high transmission areas) can develop anemia due to
frequent destruction of the red blood cells by the malaria parasites.
Severely anemic patients might receive blood transfusions which, in
developing countries, can expose them to HIV and other bloodborne diseases
- Babies
born to women who had malaria during their pregnancy are more often
born with a low birth weight or prematurely, which decreases their chances
of survival during early life
- In
developing countries, the harmful effects of malaria may combine with
those of other highly prevalent diseases and conditions, such as malnutrition,
HIV/AIDS, and anemia of all causes. Such combinations can have severe
results, especially if they occur repeatedly.
See
also: Clinical
Features
See
also: Interaction of HIV and Malaria slide set
Areas
Where Malaria Is Not Endemic
In
countries where malaria transmission has never existed or has been eliminated,
such as the United States, the great majority of cases occur in returning
travelers or in migrants arriving from areas where malaria is transmitted
("imported" malaria). However malaria remains a health threat
for people who live in these countries:
- Most
patients have no protective immunity, and when they get malaria they
can develop a rapidly severe, even fatal disease
- Health-care
providers are unfamiliar with malaria, and this can cause delayed or
incorrect diagnosis and treatment of the disease
- Under
certain conditions, malaria patients can transmit parasites to local
mosquitoes, which can in turn infect local residents. Left unchecked,
this course of events can re-introduce malaria in a previously malaria-free
area.
See
also: Areas
Where Malaria Is No Longer Endemic
Social
and Economic Toll
Malaria
imposes substantial costs to both individuals and governments.
Costs to individuals and their families include: purchase of drugs for
treating malaria at home; expenses for travel to, and treatment at, dispensaries
and clinics; lost days of work; absence from school; expenses for preventive
measures; expenses for burial in case of deaths.
Costs to governments include: maintenance of health facilities; purchase
of drugs and supplies; public health interventions against malaria,
such as insecticide spraying or distribution of insecticide-treated
bed nets; lost days of work with resulting loss of income; and lost
opportunities for joint economic ventures and tourism.
Such
costs can add substantially to the economic burden of malaria on endemic
countries and impede their economic growth. It has been estimated in a
retrospective analysis that economic growth per year of countries with
intensive malaria was 1.3% lower than that of countries without malaria.
more:
Social and Economic Impact
Page last modified : September
13,
2004
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
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