Malaria is a very serious infection which you can catch from a bite from an infected mosquito. The most common symptoms are high temperature (fever) and a flu-like illness. The symptoms of malaria can occur even up to a year after travelling in an area in which malaria is present. Prompt treatment for malaria is essential, as without treatment it can be fatal. This leaflet gives general information about malaria and its treatment.
What is malaria?
Malaria is a serious infection. It is common in tropical countries such as parts of Africa, Asia and South America. It is caused by a parasite called plasmodium. A parasite is an organism that lives on an animal and feeds from it. The parasite is passed to humans from a mosquito bite.
There are five main types of plasmodium that cause the disease. These are called Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium knowlesi. Plasmodium falciparum is usually the most serious. Occasionally people have infection with more than one type.
Symptoms of malaria
Symptoms may include:
- A very high temperature (fever). There may be sweats or shivering. This is a common symptom but a normal temperature does not rule out the possibility of malaria.
- Loss of appetite.
- Tummy upsets such as feeling or being sick, having diarrhoea or tummy pains.
- Sore throat.
- Feeling out of breath.
- Joint or muscle pains.
Symptoms usually occur between one to eight weeks after the initial mosquito bite. (This is the incubation period.) However, in some cases, depending on the type of plasmodium causing the infection, it can take up to a year before any symptoms start to show. The illness may start off with nonspecific flu-like symptoms.
There are two general types of malaria: uncomplicated and severe (complicated). Severe or complicated malaria is more serious and difficult to treat, and is more likely to be life-threatening.
Any of the symptoms above may occur. The fever in most people has no specific pattern and may present 1-2 days after the symptoms start. If the malarial infection becomes established then symptoms can come in cycles, occurring every 2-3 days.
Severe (complicated) malaria
The more severe condition occurs when complications develop. It is most commonly caused by Plasmodium falciparum. It usually begins with similar symptoms to uncomplicated malaria, but serious problems in various body organs or systems develop, including:
- Cerebral malaria: the brain or nervous system is affected. There may be lower levels of consciousness, coma or fits (seizures).
- Kidney or liver problems.
- Serious breathing problems.
- Low sugar levels.
- Very low blood pressure.
- Abnormalities of blood clotting.
Note: pregnant women are at particular risk of severe symptoms and should, ideally, not go to risk areas. This is because your immune system can be weaker during pregnancy. If you are pregnant and have malaria, you may pass the infection on to your baby.
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How common is malaria?
It was estimated that worldwide there were 219 million cases and 435,000 deaths from malaria in 2017.
The disease is uncommon in the UK. It is very rare to 'catch' malaria in the UK as the mosquitoes which transmit it cannot thrive in the UK climate. People who have or develop malaria in the UK have usually been bitten by an infected mosquito in another country. This is called imported malaria., Most infections diagnosed in the UK occur in travellers returning to the UK (rather than visitors coming to the UK). A total of 1,792 cases of imported malaria (and six deaths from the infection) were reported in the UK in 2017. Most cases were caused by Plasmodium falciparum.
Areas where malaria is common are in the tropical or subtropical parts of the world. This includes most of Africa, Asia, and significant parts of South America. It is not generally a risk in Western Europe, the USA, Australia or New Zealand.
The risk of getting the disease is greatest if you do not take your antimalarial medication or do not take it properly. People who take last-minute holidays and also those visiting friends or relatives abroad have been shown to be the least likely to take their antimalarial medication.
Note: malaria can kill people very quickly if it is not diagnosed promptly. If you feel unwell and have recently visited an area known to be affected, you should seek prompt medical advice, even if you have taken your antimalarial medication correctly.
How is malaria transmitted?
The plasmodium parasite is usually transmitted by a particular species of mosquito, which is the anopheles mosquito. If a female anopheles mosquito bites a person who is infected with malaria, the infected mosquito can then carry the plasmodium parasite and spread it to others when it bites and feeds from other people's blood.
When the plasmodium parasite enters your blood, it travels to your liver and then re-enters the bloodstream where it can invade your red blood cells. Eventually, these infected red blood cells burst which leads to them releasing even more of the tiny parasites into your blood. These infected red blood cells tend to burst every 48-72 hours. Each time they burst, you may experience an episode of chills, high temperature (fever) and sweating.
How is malaria diagnosed?
If you think you may have malaria then you need to seek medical advice without delay. If you have travelled to an area in which there is malaria in the previous year then you may be at risk of this disease, even if you took antimalarial medication when you were abroad. Usually your doctor will immediately refer you to a hospital or Infectious Disease Unit for rapid testing if this is the suspected diagnosis.
Your doctor will perform a blood test. The blood sample will be sent to the laboratory and will be examined for the presence of the plasmodium parasite. The type of plasmodium causing the infection will also be determined. If the first blood test is negative but your doctor suspects you have malaria then you may be asked to have another blood test taken a couple of days later.
If malaria is promptly diagnosed and treated, most people make a full recovery. Treatment is with antimalarial medicines. A number of these are available including:
- Artemisinin combination therapy (ACT) This is usually artemether-lumefantrine (Riamet®) or dihydroartemisinin-piperaquine (Eurartesim®).
- Quinine with doxycycline.
- Atovaquone-proguanil (Malarone®).
The type of medicine prescribed and the duration of treatment can vary from person to person. It depends on various factors such as:
- The type of plasmodium infection that you have.
- If you have taken any antimalarial medication when you were travelling.
- The severity of your symptoms.
If your symptoms are mild then you will be treated at home. However, if you have the Plasmodium falciparum type or are pregnant then it is very likely you will be treated and monitored in hospital. This would also be needed if there are complications, or for children or elderly people.
Some people are given more than one type of medication or an alternative medication if they develop side-effects to a medication. Resistance to antimalarial medicines has become a problem. This means that newer medicines or a combination of medicines may be given.
If the first antimalarial medicine that you are prescribed fails to improve your symptoms, you may have to try a variety of other medicines as part of your treatment. You may find that your treatment for malaria leaves you feeling very weak and tired for several weeks afterwards.
Other advice after a diagnosis of malaria:
- Your infection will be reported to Public Health England as it is a notifiable disease, meaning doctors are obliged to report all cases.
- You should warn any others who were with you (if you caught malaria whilst travelling) to urgently report any symptoms of illness to a health care professional.
- After treatment, it is possible to have a relapse. If this occurs you may require further treatment.
- Having had malaria does not make you immune from getting it again so you would still need to take precautions if you are travelling to areas where malaria is known to be found.
- You cannot donate blood for some time after having this disease. If you donate blood regularly, inform the blood donation service of your diagnosis.
How can malaria be prevented?
There are a number of things that can protect you from malaria. See the separate leaflet called Malaria Prevention.
Further reading and references
Malaria; NICE CKS, November 2021 (UK access only)
Guidelines for malaria prevention in travellers from the UK 2018; Public Health England Annual report, January 2019
World Malaria Report 2018; World Health Organization, November 2018
Malaria: guidance, data and analysis; Public Health England
Malaria imported into the United Kingdom: 2017; Public Health England
Lalloo DG, Shingadia D, Bell DJ, et al; UK malaria treatment guidelines 2016. J Infect. 2016 Jun72(6):635-649. doi: 10.1016/j.jinf.2016.02.001. Epub 2016 Feb 12.