Malaria is a tropical disease spread by night-biting mosquitoes. When a mosquito infected with malaria parasites (plasmodia) bites you, it injects the parasites into your body. It only takes a single mosquito bite for you to become infected.

Symptoms can develop as quickly as eight days after being bitten. However, in some cases the parasites can stay inactive in the body and symptoms may not develop for up to a year.

Any type of malaria is dangerous but malaria caused by the falciparum parasite is the most serious. It can develop very rapidly and lead to severe illness and death.

When travelling to high-risk areas, be aware of the symptoms of malaria, such as fever. Seek immediate medical attention if you experience any symptoms, even several months after your trip.

Global incidence

Malaria is a huge worldwide problem. The World Health Organization (WHO) estimates that there were 243 million cases and nearly 1 million deaths from malaria in 2008. Most deaths occur in African countries close to the equator and below the Sahara desert (Sub-Saharan Africa).

Many babies and children die from malaria. WHO estimates that a child dies of malaria every 30 seconds.

Malaria in Irish travellers abroad

Thre were over 61 cases of malaria reported in Ireland in 2011. Most of the malaria imported to Ireland is caused by the falciparum parasite and is acquired in Africa.

Most Irish travellers abroad who catch malaria either do not take any malaria tablets or do not take the right tablets for the part of the world they visit. It is important to visit a travel health clinic or GP surgery for prevention advice before going to an area where there is malaria. For detailed information on malaria visit

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Where malaria occurs

Malaria is found in tropical regions of the world:

  • large areas of Africa and Asia
  • Central and South America
  • Haiti and the Dominican Republic
  • parts of the Middle East and Far East
  • some Pacific islands, such as Papua New Guinea

Although malaria is not present in Ireland, isolated outbreaks have been reported in England, particularly by airport workers and people who have contact with imported goods.

Symptoms of malaria usually appear 10-15 days after you are bitten. However, depending on the type of parasite you are infected with, it can take a year for symptoms to show.

Symptoms of malaria are similar to flu symptoms and include:

  • a high temperature (fever) of 38°C (100.4F) or above
  • sweats and chills
  • generally feeling unwell
  • muscle pains
  • headaches
  • cough
  • diarrhoea

With some types of malaria, fevers occur in 48-hour cycles. You feel cold at first with shivering that lasts up to an hour. You then develop a fever that lasts for two to six hours, followed by extreme sweating.

Falciparum malaria

Falciparum malaria is the most serious type of malaria and can develop very quickly into a severe, life-threatening illness.

Symptoms can develop as quickly as eight days after you are bitten. Without treatment, you rapidly develop complications, such as breathing problems, fits, liver failure and shock (see Complications of malaria). The most serious complication occurs when the falciparum parasite gets into the brain's blood vessels. This can lead to a coma and death.

It is important to seek medical help as soon as possible if you experience any of the symptoms of malaria, even if it is several months after your travels.



A fever is when you have a high body temperature (over 38C or 100.4F).


An ache is a constant dull pain in a part of the body.


Diarrhoea is the passing of frequent watery stools when you go to the toilet.


Nausea is when you feel like you are going to be sick.


The liver is the largest organ inside the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy.


The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

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Malaria is caused by a parasite (an organism that lives and feeds off another organism) known as plasmodium. There are many different types of plasmodium, but only five cause malaria in humans:

  • Plasmodium falciparum is mostly found in Africa. It is responsible for the majority of malaria deaths worldwide.
  • Plasmodium vivax is found mainly in Asia and Latin America. This parasite produces less severe symptoms than plasmodium falciparum, but can stay in the liver for up to three years, which can result in relapses of the condition.
  • Plasmodium ovale is usually found in Africa. Relatively uncommon, this parasite can stay in your blood for several years without producing any symptoms.
  • Plasmodium malariae is relatively rare. Usually, it is only found in West Africa.
  • Plasmodium knowlesi is extremely rare. It is found in parts of Southeast Asia.

How the parasite is spread

The plasmodium parasite is spread by female anopheles mosquitoes. If a mosquito bites a person infected with malaria, it can then carry the parasite and spread it to other people after it has developed in the mosquito.

When the parasite enters your blood through a bite, it travels straight to your liver. It develops there and then re-enters your bloodstream and invades your red blood cells. Once in the red blood cells, the parasites grow and multiply. Eventually, the infected red blood cells burst and release even more parasites into your blood.

The infected cells usually burst every 48-72 hours. Each time this happens, you will experience an attack of chills, fever and sweating.

The female mosquitoes usually bite between dusk and dawn and are known as night-biting mosquitoes.

Pregnancy and malaria

If you are pregnant, the physical changes in your body make you more attractive to biting mosquitoes. If you catch malaria while you are pregnant, you are at risk of developing severe malaria and there is a higher risk of miscarriage and stillbirth. Your baby is also more likely to be born too early. Both you and your baby are more likely to die of complications of malaria.

The World Health Organization (WHO) advises all pregnant women to avoid travelling to malarial regions.



Malignant is a term used to describe a life-threatening or worsening condition. In the case of tumours, malignant means cancerous.


Benign refers to a condition that should not become life threatening. In relation to tumours, benign means not cancerous.


The liver is the largest organ inside the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy.


Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.


A fever is when you have a high body temperature (over 38C or 100.4F).

Immune system

The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

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If you are abroad and start showing symptoms that could be malaria, go to the nearest doctor or hospital as quickly as possible. You will usually need to give a blood sample so the doctor can check for parasites.

If you start showing symptoms when you are back home, tell your GP or hospital doctor without delay. Your doctor will ask about your symptoms and look at your travel history. You must tell them you have been to an area with a risk of malaria, including brief stopovers.

A blood test for malaria should be taken, usually by your local hospital rather than your GP surgery. A small amount of blood is taken and mixed with a special solution before being looked at under a microscope. This test will be able to confirm if you have malaria parasites in your blood and what type of parasite is causing your malaria.

You will receive your results on the same day and, if you have malaria, must start treatment straight away.

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Malaria can be a very serious illness and is potentially fatal. The falciparum parasite causes the most severe malaria symptoms and the most deaths.


The destruction of red blood cells by the malaria parasite can cause severe anaemia. This is a condition where the red blood cells are unable to carry enough oxygen, which leaves you feeling drowsy, weak and faint.

Cerebral malaria

In some rare cases of malaria, the infected red blood cells can block the small blood vessels leading to the brain, stopping blood flow and leading to a shortage of oxygen. This is known as cerebral malaria.

Cerebral malaria can cause your brain to swell and, in some cases, may lead to permanent brain damage. It can also cause you to have a seizure or fall into a coma.

Other complications

Other complications of a severe case of malaria can include:

  • breathing problems (such as fluid in your lungs)
  • liver failure and jaundice (a yellow discolouration of the skin)
  • shock (sudden drop in blood flow)
  • spontaneous bleeding
  • abnormally low blood sugar
  • kidney failure
  • swelling and rupturing of the spleen
  • dehydration

Complications of severe malaria can appear within hours or days of your first symptoms, so it is important to get urgent medical help as soon as you think you have malaria.

Malaria is usually more severe in pregnant women, babies, young children and older people.



Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Blood vessels

Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.


The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.


A coma is a sleep-like state when someone is unconscious for a long time.


Dehydration is an excessive loss of fluids and minerals from the body.


The liver is the largest organ inside the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy.


Jaundice is a condition that causes yellowing of the skin and the whites of the eyes, brought on by liver problems.


Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.

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Antimalarial medicine for prevention

If you are travelling to an area with a risk of malaria, your doctor will recommend you take antimalarial tablets to prevent you from becoming infected. The antimalarial tablets that you are prescribed will be based on the following factors:

  • where you are going
  • medical history, including any drug allergies
  • relevant family medical history
  • current medicines
  • any problems with antimalarial medicines in the past
  • your age
  • whether you are pregnant 

Sometimes, you need to take a short trial course of antimalarial tablets before you go. This is to check that you do not experience any side effects or reactions. If you do, alternative antimalarials can be prescribed before you leave.

Long-term travel

If you are planning to go away for more than six months, you are considered a long-term traveller.
When travelling to areas where there is a risk of malaria, always consider taking antimalarial medicine. If you are travelling to different places, you may only need to take antimalarials for part of your trip.

Discuss your options at a specialist travel health clinic or your GP surgery as soon as possible.

Antimalarial medicine for treatment

With prompt diagnosis and treatment, most people make a full recovery from malaria. If you have been diagnosed with malaria, your treatment must start as soon as possible.

Malaria can be treated using the same antimalarial medicines taken to prevent malaria. However, if you have taken a preventive anti-malarial medicine, your doctor should not give you the same one to treat your malaria. Therefore, it is important you tell your doctor what tablets you took to prevent malaria.

The antimalarial medicine that you are prescribed and the length of your treatment depend on:

  • the type of malaria you have
  • how bad your symptoms are
  • where you caught malaria
  • if you took antimalarial tablets
  • whether you are pregnant
  • your age

Your doctor will check the most recent advice and recommend the right treatment for you. They may recommend a combination of different medicines to overcome strains of malaria that have become drug-resistant.

Often, antimalarial treatment is given as tablets or capsules. If you are very ill, you will be admitted to hospital and treatment is usually given through a drip into a vein in your arm.

Treatment for malaria can leave you feeling very weak and tired for several weeks.

Emergency standby treatment

This is a course of medicine that can be taken for malaria symptoms if you cannot reach a doctor while you are travelling overseas.

Research has shown that emergency standby treatment is often used incorrectly. It should only be considered for travellers who are going to be in very remote areas away from medical help.

It is not a substitute for taking the right malaria prevention tablets. Your doctor should get advice from a travel health specialist before prescribing emergency standby treatment.

Types of antimalarial drugs

There are five medicines used to prevent malaria.

Atovaquone plus proguanil (also known as Malarone)

  • Prevention: the adult dose is one adult-strength tablet a day. Child dosage is also once a day, but the amount depends on the child's weight. It should be started just one or two days before your trip, taken all the time that you are in a risk area and for seven days after you get back.
  • Recommendations: lack of research means that this drug is not usually recommended for pregnant or breastfeeding women. It is also not advised for people with severe kidney problems.
  • Possible side effects: intestinal upset, headaches, skin rash and mouth ulcers.
  • Other factors: it is more expensive than other antimalarials so may be more suitable for use on short trips.

Chloroquine (also known as Avloclor tablets and Nivaquine syrup)

  • Prevention: the adult dosage is two tablets taken once a week. Child dosage is also once a week but the amount depends on the child's weight. Nivaquine is available in a syrup for small children. It must be started one week before you travel, taken all the time you are in a risk area and for four weeks after you return.
  • Recommendations: it is not recommended for people with liver or kidney problems, psoriasis or epilepsy.
  • Possible side effects: bitter taste, nausea (which may be reduced by taking tablets after food), headache, skin itching in people of African descent and eye problems after years of continuous use.
  • Other factors: chloroquine is one of the oldest antimalarial medicines and many strains of malaria are now resistant to it.

Doxycycline (also known as Vibramycin-D)

  • Prevention: the dose is 100mg daily as a tablet or capsule. You should start the tablets two days before you travel, and take them all the time you are in a risk region and for four weeks after you return.
  • Recommendations: it is not suitable for pregnant or breastfeeding women, children under 12 (because of the risk of permanent tooth discolouration), people who are sensitive to tetracycline antibiotics or people with liver problems.
  • Possible side effects: sunburn due to light sensitivity, stomach upset, heartburn and thrush. It should always be taken with food, preferably when standing or sitting. Doxycycline initially reduces the effectiveness of combined hormone contraceptives, such as the pill or patches.
  • Other factors: if you take doxycycline for acne, this will provide protection against malaria, as long as you are taking an adequate dose (ask your GP). Doxycycline is relatively cheap.

Mefloquine (also known as Lariam)

  • Prevention: the adult dose is one tablet weekly. Child dosage is also once a week but the amount will depend on the child's weight. It should be started three weeks before you go and taken all the time you are in the risk region and for four weeks after you get back.
  • Recommendations: it is not recommended if you have epilepsy, seizures, depression or psychiatric problems, or if a close relative has any of these conditions. It is not usually recommended for people with severe heart or liver problems.
  • Possible side effects: dizziness, headache, sleep disturbances (insomnia and vivid dreams) and psychiatric reactions (anxiety, depression, panic attacks and hallucinations). It is very important to tell your doctor about any previous psychiatric problems, including mild depression. You should not take this medication if you have a seizure disorder.
  • Other factors: if you have not taken mefloquine before, it is recommended that you do a three-week trial before you travel to see if you develop any side effects.

Proguanil (also known as Paludrine)

  • Prevention: the adult dosage is two proguanil tablets each day (usually taken with two tablets of chloroquine once a week, on the same day each week). Child dosage is also proguanil daily and chloroquine once a week, but the amount will depend on the child's weight. You should start taking it one week before travel and continue all the time you are in a risk area and for four weeks after you return.
  • Recommendations: proguanil should be used with caution if you are taking a medicine to prevent blood clots (an anticoagulant, such as warfarin) or if you have kidney problems.
  • Possible side effects: mouth ulcers, diarrhoea, nausea and anorexia.
  • Other factors: the major disadvantage of taking proguanil and chloroquine is that resistance has developed in many areas, so the drugs are no longer effective.

Taking antimalarials during pregnancy

If you are pregnant, avoid travelling to areas where there is a risk of malaria. Pregnant women have an increased risk of developing severe malaria and it is more dangerous for them and their baby.

If you feel you must travel to malaria risk areas while pregnant, it is important to take the right antimalarial medicine. Some of the drugs used to prevent and treat malaria are unsuitable as they may cause side effects for you and your baby.

  • Chloroquine and proguanil are safe to use at any stage of your pregnancy without harm to you or your baby. It is recommended that you take a 5mg folic acid supplement while you are taking proguanil. Chloroquine alone or the combination with proguanil does not offer enough protection in many regions, including Africa.
  • Mefloquine (Larium) is not usually prescribed in pregnancy. However, if travel is unavoidable, it can be considered for countries with a high risk of malaria.
  • Doxycycline is never recommended for pregnant or breastfeeding women  in Ireland as it could harm the baby.
  • Atovaquone and proguanil (Malarone) is generally not recommended as there is only limited research on use of this drug in pregnancy. If the risk of malaria is high, it can be taken if mefloquine is not suitable.

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Finish your course of tablets

Malaria parasites can stay inactive in your blood and suddenly reawaken, so it is important that you complete your course of antimalarial tablets.

Check with your GP or pharmacist exactly how long you should take your medicine.

The risk of malaria for people travelling to affected areas is significant, so it is important to take precautions to prevent it. Most of the malaria imported to the UK is caused by plasmodium falciparum and is acquired in Africa.

Many cases of malaria can be prevented by the ABCD approach:

  • Awareness of risk: know your risk of malaria.
  • Bite prevention: avoid bites as much as possible.
  • Chemoprophylaxis: take the right antimalarial tablets.
  • Diagnosis: get immediate medical help for symptoms.

Awareness of the risks

You can check whether you need to take preventative malaria treatment for the country that you are visiting by looking at the or websites.

Visit your GP or local travel clinic for advice on malaria and other health risks as soon as you know that you are going to be travelling.

Bite avoidance

While you will not be able to avoid bites completely, the less you and your family are bitten, the less likely you are to catch malaria. Below are a number of things you can do to help prevent being bitten by mosquitoes:

  • Ideally, stay somewhere with effective air conditioning and screening on doors and windows. If this is not possible, try to stay somewhere with doors and windows that close.
  • If you are not sleeping in an air-conditioned room or if the air-conditioning is not effective, you must sleep under an intact mosquito net that has been treated with insecticide.
  • Use insect repellent on your skin and in sleeping environments. Remember to reapply frequently.
  • The most effective repellents contain diethyltoluamide (DEET) and are available in sprays, roll-ons, sticks and creams.
  • Wear light, loose-fitting trousers, rather than shorts, and shirts that have long sleeves. This is particularly important during early evening and at night, as this is the mosquito's preferred feeding time.

Garlic, vitamin B and ultrasound devices do not prevent bites.

Chemoprophylaxis: taking appropriate antimalarial tablets

Taking medicine to prevent catching malaria is essential for all travellers who are visiting areas with malaria. However, antimalarials are not 100% effective, so avoiding bites is also important.

Taking antimalarial medicine:

  • Make sure you get the right antimalarial tablets before you go.
  • You will have to pay for your antimalarials, so include the cost in your trip budget.
  • Follow the instructions included with your tablets carefully.
  • It is important that you continue to take your tablets after you return from your trip. This is to cover the incubation period of the disease.
  • Most tablets need to be taken for four weeks after you return, although atovaquone plus proguanil (Malarone) needs to be taken for only one week.

Talk to your doctor to make sure that you are prescribed a drug you can tolerate. You may be more at risk from side effects if you have:

  • epilepsy or any type of seizure
  • depression
  • heart problems
  • liver or kidney disease
  • porphyria (an inherited condition that causes sensitivity to sunlight)
  • psoriasis
  • psychiatric problems

You may also be more at risk from side effects if: 

  • your spleen has been removed or does not work properly
  • you take medicine (such as warfarin) to prevent blood clots
  • you are a woman using combined hormonal contraception, such as the pill or patches

If you have taken antimalarial medicine in the past, do not assume that it is suitable for future trips. The medicine you need to take depends on the strain of malaria carried by the mosquitoes and drug resistance in the region that you are travelling to.

Diagnosis: get prompt medical advice

If you become ill when you get back from travelling, even if you took the right malaria prevention tablets, you must see your GP or a hospital doctor straight away.

Tell the doctor that you have been exposed to malaria. It is important that you tell them which countries you have travelled to in the last 12 months, including brief stopovers.

Malaria can develop very quickly, so it is important to get medical advice, diagnosis and treatment as soon as possible if you think you may have malaria.


A disease is an illness or condition that interferes with normal body functions.

The sac-like organ of the digestive system. It helps digest food by churning it and mixing it with acids to break it down into smaller pieces.

Nausea is when you feel like you are going to be sick.

Diarrhoea is the passing of frequent watery stools when you go to the toilet.

An ulcer is a sore break in the skin or on the inside lining of the body.

Anxiety is an unpleasant feeling when you feel worried, uneasy or distressed about something that may or may not be about to happen.

Depression is when you have feelings of extreme sadness, despair or inadequacy that last for a long time.

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Is DEET safe?

The chemical DEET (diethyltoluamide) is commonly used in mosquito repellents.

It is not recommended for use on children aged under two months.

It is safe for older children, adults and pregnant women when used according to the manufacturer’s instructions:

  • Use on exposed skin.
  • Do not spray directly onto your face, but spray into your hands and pat onto your face.
  • Avoid contact with lips and eyes.
  • Wash hands after applying.
  • Do not apply to cuts, abrasions, broken or irritated skin.
  • Avoid sunscreen containing mosquito repellent.
  • Wash off repellent when you are no longer exposed to mosquitoes.

Content provided by NHS Choices and adapted for Ireland by the Health A-Z.

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