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Malaria is an infectious disease that is spread by mosquitoes, in particular female
mosquitoes of the genus Anopheles. Malaria is a disease that is found in hundreds of
different countries around the world and over 3 billion people are at risk from the
disease.
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Note this slide is animated
Malaria is caused by a eukaryotic protist, a single celled organism. The parasite belongs
to a genus known as Plasmodium. The image shows a false coloured micrograph
showing one of the life stages of the parasite (shown in blue) inside human red blood
cells.
Four species of Plasmodium infect humans:
• Plasmodium falciparum
• Plasmodium vivax
• Plasmodium malariae
• Plasmodium ovale
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Plasmodium falciparum and Plasmodium vivax are the parasites that cause the most
cases of malaria worldwide. (Other two species are greyed out.)
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Plasmodium falciparum can cause serious complications and can be fatal if untreated. It
is responsible for the most deaths due to malaria. (Plasmodium vivax is greyed out)
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Plasmodium has a complex life cycle. Part of it takes place inside a human host and part of it
takes places inside a mosquito vector.
There are essentially five key stages to the Plasmodium life cycle:
1. The Anopheles mosquito bites a human injecting the Plasmodium parasite which enters the
humans blood. At this stage the parasite is in a form known as a sporozoite, which is long
and thin and is capable of moving in between and within cells.
2. The parasite travels in the blood until it reaches the liver. At this point the parasite
recognises and invades liver cells where it remains for around 10 days. In the liver it
undergoes a transformation into thousands of new parasites known as a merozoites. These
newly formed merozoites are released into the bloodstream.
3. The merozoites invade red blood cells and then reproduce. Each merozoite enters a red
blood cell and once inside it grows and divides asexually to form up to 20 new merozoites.
These burst out of the cell and invade neighbouring red blood cells. This whole process takes
approximately 48 hours.
4. Some parasites do not form merozoites but develop into a sexual stage of the lifecycle called
gametocytes. These are taken up by a mosquito when they feed on an infected human.
5. Once inside the mosquito gut the gametocytes change into mature gametes (eggs and
sperm) which fuse and develop into an ookinete. The ookinete burrows through the lining of
the mosquito’s gut wall where it forms an oocyst in which tens of thousands of sporozoites
are formed. They burst out of the oocyst and travel to the salivary gland of the mosquito
where the cycles begins again.
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Stage 1 : Transmission to human
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Stage 2: Liver stage
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Stage 3: Red blood cell stage
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Stage 4: Transmission to mosquito
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Stage 5: Mosquito stages
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According to the World Health Organization, there were 225 million cases of malaria
worldwide and 781,000 deaths in 2009. Although this is a lot, these numbers have
decreased from 233 million cases and nearly 1 million deaths in 2000.
The majority of malaria deaths are due to the Plasmodium falciparum parasite and are in
children under the age of five in Africa.
Pregnant woman are also vulnerable to malaria as they have lower natural immunity to
the disease. If they are infected with malaria when pregnant this can have a serious
impact on their unborn child. Pregnant women with malaria are susceptible to:
• placental infections (a build up of parasites in the placenta) that can lead to
miscarriage
• death of newborns due to premature birth or low birth weight.
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Pregnant women and children under the age of five are most vulnerable to malaria
infections. This is because they have a lower natural immunity to the disease compared
to others in the community.
Adults can also be affected by malaria, however if they have lived in the same area for a
long period of time they are likely to build up some immunity to the parasite. This does
not mean that they are not infected but may mean they have less severe symptoms.
People who travel from malaria free areas to malaria endemic areas are also at risk of
contracting the disease. Holiday makers and immigrant workers can be vulnerable to
infections as they have no immunity to the disease. Drugs are available that can be given
to these people to kill the parasite if they become infected.
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This map shows areas where Plasmodium falciparum is endemic around the world. You
can see that the highest levels of malaria are between the Tropics of Cancer and
Capricorn.
Malaria is a disease of the developing world affecting people in some of the poorest
countries, especially in sub‐Saharan Africa. It is considered a disease of poverty but is
also a major cause of poverty .
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These are images from four regions where malaria is found: Cambodia in South East Asia
(top left), Dar Es Salaam, Tanzania, Africa (top right) Shanty town in India, (bottom left),
a remote rural village in Peru, South America (bottom right).
Question to the students: Why do you think these areas have high levels of malaria?
What do they have in common?
• Warm climate (over 19‐20 °C) and heavy rainfall. Long rainy seasons can form areas
of standing water which are ideal mosquito breeding grounds.
• Poor housing and sanitation facilities. The houses in these areas don’t always have
windows or mesh screens to prevent mosquitoes and other biting insects entering
the house.
• Some are in rural areas, in close proximity to forest (except Dar es Salaam in
Tanzania) which provides ideal habitats for some mosquito species.
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Malaria causes significant economic losses, and can decrease gross domestic product
(GDP) by as much as 1.3% in countries with high levels of transmission. It is estimated
that malaria‐related health expenditure and lost productivity costs Africa’s economy
over $8 billion per year. It also deters foreign investment, tourism and trade. These
sustained annual economic losses have resulted in substantial differences in GDP
between countries with and without malaria, particularly in Africa.
Malaria disproportionately affects poor people who cannot afford treatment or have
limited access to health care. This traps families and communities in a vicious cycle of
poverty and disease which they are unable to break away from.
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Early diagnosis and treatment of malaria reduces disease and prevents deaths. It also
contributes to reducing malaria transmission. There are two ways malaria can be
diagnosed: Microscopy and rapid diagnostic tests (RDTs).
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Microscopy ‐ a blood sample is taken from the patient and is looked at under the
microscope. If parasites are visible within the blood smear they are diagnosed as having
malaria.
Question to the students: What are the limitations of microscopy?
The key limitation is that this method of diagnosis can only be used in laboratories
where there is electricity and trained medical staff.
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The second method of diagnosis is RDTs.
RDTs are quick tests that use a drop of blood from the finger tip to identify if the patient
has malaria. The tests are sensitive to antigens (proteins that are produced by the
parasite) that bind with a dye to form a coloured strip (a bit like a pregnancy test) to
indicate whether there are parasites in the blood. The image shows a test and you can
see two strips, one is the control strip and the other indicates a positive result.
An RDT takes just 15 minutes and can be used in rural communities by trained
community workers, making this a valuable and life saving diagnostic tool.
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Anti‐malarial drugs kill the parasite but do not prevent the patient from being re‐
infected. Early and effective treatment of malaria with anti‐malarial drugs can shorten
the duration of the infection and prevent further complications which could be fatal.
In many countries, anti‐malarial drugs can be purchased over the counter without
prescription from doctors or medical practioners. This can lead to inappropriate use of
the drugs, for example, if someone has a fever they may take anti‐malarial drugs when
malaria is not the cause of the fever. This uncontrolled use of single drug therapies, such
as chloroquine, in the past has led to parasites developing drug resistance. This causes
great problems as the drugs available to patients are ineffective and cannot be
prescribed to treat the disease.
A new compound known as artemisinin was found to be effective against malaria in the
1990s. It is now used in combination with other drugs particularly to deal with
Plasmodium falciparum infections. Artemisinin is recommended as first line treatment
for malaria by the World Health Organization.
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Protection against mosquito bites and controlling vector populations are effective
methods of preventing malaria transmission. Vector control in particular works to reduce
malaria transmission at a community level and can significantly reduce transmission
from very high levels to close to zero. For individuals, personal protection against
mosquito bites through the use of bed nets and insect repellents is the first line of
defense to prevent malaria.
Insecticide‐treated nets (ITNs) and long lasting insecticide impregnated nets (LLINs) offer
both a physical and chemical barrier to mosquitoes.
LLINs are the preferred form of insecticide treated nets for public health distribution
programmes and recommended by the World Health Organization as they can be
effective for 3‐5 years.
Indoor residual spraying (IRS) with insecticides is an extremely effective way to rapidly
reduce malaria transmission. It can be effective for 3‐6 months, depending on the
insecticide used and the type of surface on which it is sprayed. DDT can be effective for
9‐12 months in some cases.
Drugs can also be used to prevent malaria. For travellers, malaria can be prevented
through chemoprophylaxis, taking drugs that suppress the blood stage of malaria
infections, thereby preventing malaria disease.
Pregnant women are also offered anti‐malarial drugs during their pregnancy. This is
known as Intermittent Preventive Treatment in pregnancy (IPTp). This practice aims to
reduce the possible complications during pregnancy such as severe anaemia and
placental infections which can threaten the life of the mother and child.
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The Malaria Challenge is a multimedia resource which can provide you with information
on the lifecycle of the malaria parasite and how the disease can be treated and
prevented. It includes videos, animations and interviews with malaria researchers to give
an insight into the many different issues surrounding this topic. This information can be
used to find out more about malaria and enable students to take part in a discussion
based activity.
Use the following slide(s) to introduce the discussion activity you have decided to run.
Hide the two slides that are not relevant to the activity that you decide to run, e.g. if you
are running the Big Debate, hide slides 15 and 16.
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In this activity each group will randomly select a stage of the malaria life cycle.
All members of the group must research the particular lifecycle stage they have been
allocated using the Malaria Challenge resource. You should identify the stage’s relevance
in the disease lifecycle and the prevention interventions that specifically target it.
Then as a group discuss the advantages and disadvantages of the prevention
interventions and how effective they could be at eradicating malaria.
By the end of this discussion each member of the group should be clear on the issues
surrounding the malaria stage and its prevention interventions. They are now “experts”
and should have each completed a worksheet with key points from the group
discussions.
The next stage is to form new groups with an “expert” from each malaria stage. In these
newly formed groups each person will take it in turns to put forward their thoughts and
findings on their particular stage of the malaria lifecycle. After this, as a group, put
together an argument for the three best methods or techniques to eradicate malaria
which the spokesperson(s) will present to the rest of the class.
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Form “expert” groups to discuss the best methods to eradicate malaria.
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Feedback your thoughts to the class.
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Before starting the discussion the group should nominate the following roles:
• Spokesperson(s): the person or persons who will speak on behalf of the group
during the feedback session
• Scribe: the person responsible for taking notes on all the discussion and completing
the group worksheet
• Financier: the person responsible for doing the calculations and ensuring that the
available funds are correctly allocated and the group doesn’t overspend!
The first stage of the discussion process is to consider funding principles, a set of
considerations or guidelines to help the group in their decision making. Ideas for funding
principles include:
• Should you only fund projects in malaria endemic countries?
• Should the project have to use innovative technology?
• Will the project have a large scale impact?
• Should a project you fund further advances in the understanding of malaria?
• Should a project you fund further advances in the treatment of malaria?
As a group discuss each of the funding applications in turn, discussing their advantages
and disadvantages. Once a decision has been made place the card in a yes, no or maybe
pile. The scribe should complete the group worksheet with the assistance of the
financier.
Note: They do not have to spend all of the money. If they do not think all of the projects
should receive funding, then they can leave surplus funds.
Once they have completed their worksheet, the spokesperson should prepare to feed
back their decisions to the rest of the class with explanations as to why they chose those
particular projects.
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In this activity the students will be playing the role of malaria programme managers for a
community in a malaria endemic area. These regions are Cambodia, Uganda, Tanzania
and Brazil.
In groups they must assess the situation facing their allocated community and propose a
strategy that will work towards eliminating malaria from the region.
The groups must present their proposal to the rest of the class and summarise their
reasons for suggesting this strategy.
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These discussion guidelines apply to all of the activities, make sure these guidelines are
followed during the activity. Everyone should contribute to the discussion and no one
should be excluded.
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