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Malaria - the disease

Key points

  • Malaria is a serious disease that is passed on by infected mosquitoes.
  • The first symptoms of malaria are usually fever and a headache.
  • It’s very important to see a doctor if you develop symptoms after being in a malaria zone.
  • Malaria can be treated with medicines but it’s important to start these as soon as possible.

What should I do if I think I have malaria?

If you develop a fever within a week or more of arriving in a country where malaria is present, see a doctor or a health professional within 24 hours. If you get any illness that you think could be malaria within a year of returning from an area where malaria is common, see your GP as soon as possible.

Malaria is an infectious disease that is caused by a parasite called Plasmodium. You get it from the bite of a type of female mosquito that carries the parasite.

About malaria

Malaria is an infection that can cause serious illness and may be life-threatening. You get malaria from the bite of a type of infected female mosquito called Anopheles. They carry a parasite called Plasmodium, which is carried to your liver and then infects your red blood cells.

Malaria is common in tropical areas including sub-Saharan Africa, Central and South America, the Indian subcontinent, South East Asia and the Pacific Islands. You can’t catch malaria in the UK. However, about 1,500 people are treated for it in the UK each year having become infected while abroad.

Illustration showing the distribution of malaria throughout the world

Symptoms of malaria

It usually takes between seven and 30 days for the symptoms of malaria to develop but it can take longer. This is called the incubation period. It’s more likely to take longer if you’re infected with one of the less severe types of malaria. It may take up to a year before you have any symptoms. The incubation period can also vary depending on whether or not you have taken any medicines to prevent malaria. You can still catch malaria even if you have taken antimalarial medicines correctly.

The first symptoms of malaria are similar to those of flu. You may have:

  • a fever
  • a headache
  • aching muscles
  • a tummy ache, diarrhoea and vomiting – especially in children
  • a lack of energy
  • loss of appetite
  • a cough

It’s rare but some people have malaria attacks that happen every two or three days and last between six and 10 hours. These have three stages: feeling cold and shivering; fever and headaches; sweating and tiredness.

If you have an illness with a fever and have travelled to a region with malaria within the last year, visit a doctor. Always tell him or her where you have travelled. The symptoms of malaria can get worse very quickly and therefore it’s important to get immediate treatment.

Complications of malaria

Malaria can progress to a more severe form (also called complicated malaria). This is more likely if you’re infected with Plasmodium falciparum. Complications can affect your brain, kidneys, blood and lungs. They can develop within hours or days of your first symptoms and can be fatal within 24 hours. This is a medical emergency.

Symptoms of severe malaria can include:

• jaundice – yellowing of your skin or the whites of your eyes
• fluid on your lungs – this is called pulmonary oedema and can lead to difficulty breathing
• low blood sugar (hypoglycaemia) – this can make you feel light-headed or shaky
• bleeding
• pale skin
• fits
• loss of consciousness

Severe malaria is more likely in:

• pregnant women
• children under the age of five
• elderly people
• people who have a weakened immune system, such as those with HIV/AIDS

Causes of malaria

Malaria is caused by an infection with a parasite called Plasmodium that is passed to people through mosquito bites. Mosquitoes aren’t affected by the parasite.

Malaria parasite

You can catch malaria if a female Anopheles mosquito bites someone carrying the malaria parasite and then bites you. The parasite is passed on to you in infected blood. This type of mosquito is most active at dusk and during the night. Therefore, if you’re out at these times, it’s important to cover up with loose-fitting clothes with long sleeves, long trousers and socks.

There are four main types of Plasmodium parasite that infect humans. These are Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae. Of these, Plasmodium falciparum is the most severe form and causes most deaths from malaria. The other three types can stay in your body for a long time and may cause your symptoms to come back months or years later.

About seven out of 10 UK travellers who get malaria are infected with Plasmodium falciparum. You can be infected with more than one type of Plasmodium parasite but this is uncommon. Each parasite can cause slightly different symptoms.

Parasite lifecycle

The malaria parasite is carried in your blood to your liver where it grows and develops.

After it has completed its development, the parasite leaves your liver and travels back into your bloodstream. It then enters and attacks your red blood cells, which you need to carry oxygen around your body. You will then get symptoms of malaria.

Diagnosis of malaria

Your doctor will ask about your symptoms and examine you. He or she will ask you about which countries or regions you have visited within the last year. It’s very important that you tell him or her if you have travelled abroad. This includes any stopovers you have had.

Malaria is a medical emergency and needs to be treated as soon as possible. If your doctor suspects that you have malaria, he or she may do a blood test. Alternatively, if it’s not possible to get the results within four hours, you may be referred to hospital for the test. This is to find out what type of parasite you have been infected with and how much there is in your blood. If your blood test is negative, you will still need to have two further blood tests over one to three days. This is because the levels of parasite in your blood can vary. For example, if you have taken antimalarial medicines, the levels of parasite may be too low to detect.

If you’re diagnosed with malaria, your doctor must tell the public health authorities. It’s important that anybody you travelled with also gets tested for malaria. He or she may be infected but not know as symptoms don’t always develop immediately.

Treatment of malaria

Malaria can be treated with medicines but it’s important that you start these as soon as possible. Your treatment will depend on a number of things including what type of malaria you have. Certain medicines don't work for malaria from some parts of the world – your doctor will ask where you have been and take this into account. The length of time that your treatment takes will vary depending on how severe your infection is.

Some medicines used to treat malaria are also used to help prevent the infection. However, if you have taken a medicine to prevent malaria, you can't take the same one again to treat it. Therefore, it's important to tell your doctor about any antimalarial medicines you have taken – if possible, take the medicine packaging to your appointment.


Treating mild P. falciparum malaria
If you have P. falciparum malaria, even if your symptoms are mild you will usually need to stay in hospital to be monitored. This is because malaria can rapidly progress and become more severe.

The three main treatments for mild P. falciparum malaria in the UK are:

  • quinine followed by a second medicine, usually doxycycline but sometimes clindamycin
  • artemether with lumefantrine (Riamet)
  • atovaquone with proguanil (Malarone)

Treating severe P. falciparum malaria
The standard treatment for severe P. falciparum malaria is quinine, which will be injected directly into your blood through a vein (intravenously). Once you're well enough, you can have the rest of your treatment as tablets that you swallow. If quinine isn’t effective, you may be given a medicine called artesunate. However, this can only be prescribed on a ‘named patient basis’. This means that although the medicine is licensed in some countries, it isn’t in the UK. However, your doctor may prescribe it for you if there is no alternative and the potential benefits are thought to outweigh the risks.

If you have severe P. falciparum malaria, you will be monitored carefully and treated for any complications.

Treating other types of malaria
If you have one of the three less severe types of malaria, you’re likely to be treated with chloroquine tablets (eg Avloclor, Malarivon or Nivaquine). It’s safe to take chloroquine if you're pregnant.

If you have malaria caused by P. vivax or P. ovale, you will need treatment to stop the infection coming back. This is because parasites can stay in your liver. You’re likely to be given primaquine after you finish taking chloroquine. If you’re pregnant, your doctor will usually advise that you wait until you have given birth before you take primaquine.

It’s likely that you will be able to take your medicines at home and won’t need to go into hospital. However, you will need to go to hospital if you develop complications or need to be given medicines intravenously.

Treating complications
If you’re diagnosed with severe malaria, your doctors will monitor you so that they can treat any complications quickly. Malaria can affect your kidneys, lungs and blood sugar level so it’s important to check these regularly.

Special considerations

Acquired immunity

If you're born in an area with malaria, you may develop some immunity to the infection. You won’t be completely protected but your risk of developing severe malaria may be reduced. However, if you leave the area, you will quickly lose this immunity. Therefore, you will need to take antimalarial medicines if you return or go to another area with malaria.

If you're pregnant

You’re at an increased risk of severe malaria and complications if you’re pregnant. You’re also more at risk of having a miscarriage or stillbirth or your baby being born prematurely if you get malaria while you’re pregnant. It’s rare, but if you get malaria, it’s possible to pass it on to your unborn baby.

If you’re pregnant, the safest option is to not travel to an area where there is malaria. If this isn’t possible, it’s very important that you take precautions to prevent yourself from getting bitten by mosquitoes and take antimalarial medicines. Make sure you tell your doctor that you’re pregnant as this will determine which medicines you’re given. It’s also important to ensure that if you do get malaria, the doctor treating you is aware that you’re pregnant.

G6PD deficiency

This is a genetic disorder but you may not know that you have it. If you’re prescribed an primaquine, you may need to have a blood test to check that you don’t have this condition. If you have G6PD deficiency and take primaquine, it can lead to you developing anaemia and other serious side-effects.

Prevention of malaria

If you’re going to an area where there is malaria, it’s very important that you take precautions to prevent the disease. The key to this is to protect yourself against being bitten by mosquitoes. Antimalarial medicines are also available but it’s important to remember that these aren’t completely effective. Therefore, it’s vital to take steps to prevent yourself from getting bitten. Make sure that you see your GP or a travel health clinic several weeks before you travel.

Malaria vaccine

At present there isn’t a vaccine to prevent malaria. However, over 20 possible vaccines are currently being studied. The most promising one is called RTS,S/AS01 and is being tested in a phase three clinical trial. This means that its safety and effectiveness have been assessed and it’s now being tested in comparison with the current best alternative. It’s being tested in two different age groups of children in a number of African countries.

The results have shown significant decreases in the number of children who get malaria, but further testing is needed. However, it’s hoped that by 2015 it may be possible for the World Health Organization to recommend that the vaccine is licensed for use.

Reviewed by Polly Kerr, Bupa Health Information Team, February 2014.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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  • Produced by Stephanie Hughes, Bupa Health Information Team, February 2012.