Malaria - the disease

Published by Bupa's Health Information Team, March 2010.

This factsheet is for people who have malaria, or who would like information about it.

Malaria is an infectious disease found in tropical areas such as Sub-Saharan Africa, Central and South America, the Indian subcontinent, South East Asia and the Pacific islands (these are known as malarious regions). It's caused by a parasite called Plasmodium, which is passed to people through bites from mosquitoes carrying the parasite.

About malaria

There are two categories of malaria.

• Malignant malaria causes symptoms within three months of infection and can be mild or severe. It's caused by one type of malaria parasite, Plasmodium falciparum.
• Benign malaria is mild but may have a dormant stage of up to a year and can cause relapses. This is caused by the other three types of malaria parasite.

Around 2,000 people a year in the UK get infected with malaria when abroad.

Symptoms of malaria

The first symptoms of malaria are like having the flu. You may have:

• a headache
• aching muscles
• tummy ache, diarrhoea and vomiting, especially in children
• weakness or lack of energy

A day or so later, your temperature may rise. Some people have malaria attacks with three stages: shivering, hotness, and sweating. You may feel or be sick during the hot phase.

Symptoms can appear any time from six days after you are bitten by a mosquito carrying the malaria parasite. The time it takes your symptoms to appear - the incubation period - can vary with the type of parasite that the mosquito was carrying.

• If a mosquito carrying the P. falciparum parasite bites you, symptoms usually appear within three months of the bite, and most commonly start between seven and 30 days.
• If a mosquito carrying the P. vivax, P. ovale or P. malariae parasite bites you, symptoms can appear a year or more after the bite. This is because the parasite can lay dormant in your liver and become active months later. These parasites may also cause you to have repeat symptoms.

If you have an illness with a fever and have travelled to a malarious region within the last year, you should visit your GP. You can still catch malaria even if you have taken antimalarial medicines correctly.

Complications of malaria

If you get infected with P. falciparum, your malaria can progress to a more severe form (also called complicated malaria). Complications can affect your brain, kidneys, blood and lungs. They can develop within hours or days of your first malaria symptoms and can be fatal within 24 hours.

Symptoms of severe malaria can include:

• jaundice - yellow skin and eyeballs
• difficulty breathing
• feeling light-headed or shaky (symptoms of low blood sugar)
• bleeding - eg under the skin (showing as pin pricks or bruises) or from the nose or gums
• pale or bluish skin
• fast heart beat
• fast breathing
• fits
• loss of consciousness

It's important to seek urgent medical advice if you suspect you have severe malaria. Always tell your doctor where you have travelled. Complications are likely to be more severe in pregnant women, children and the elderly.

Causes of malaria

Malaria is caused by infection with a parasite called Plasmodium that is passed to people through mosquito bites.

Malaria parasite

You can catch malaria if a female of the Anopheles mosquito bites someone carrying the malaria parasite and then bites you, passing the parasite on to you.

There are four different types of Plasmodium parasite.

• Plasmodium falciparum - this is the only parasite that causes malignant malaria. It causes the most severe symptoms and results in the most fatalities.
• Plasmodium vivax - this causes benign malaria with less severe symptoms than P. falciparum. P. vivax can stay in your liver for years and can lead to a relapse.
• Plasmodium ovale - this causes benign malaria and can stay in your blood and liver for many years without causing symptoms.
• Plasmodium malariae - this causes benign malaria and is relatively rare.

About three-quarters of UK travellers who get malaria are infected with P. falciparum. Most of the other people are infected by P. vivax, and just a few are infected with the other two species. You can get infected with more than one type of Plasmodium parasite.

Each parasite causes a slightly different type of illness.

Parasite lifecycle

The malaria parasite passes through your blood into your liver, where it grows and develops.

After it has completed its development, it travels back into your bloodstream and eventually 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 you about your symptoms and examine you. He or she will ask about your medical history and will need to know which countries or regions you have visited within the last year, including any stopovers.

Your doctor will do a blood test to see if you have malaria. This may need to be repeated as the levels of malaria parasite in your blood can vary. For example, if you have taken antimalarial medicines, the levels of parasite may be too low to detect. Repeating the test can help to confirm if you have malaria.

Treatment of malaria

There are a number of medicines that can treat malaria if you start taking them soon after your symptoms appear. 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.

Some of the medicines that are used to treat malaria are the same ones used to help prevent the infection. But if you have taken a medicine to prevent malaria, you can't take the same one again as treatment. So it's important to tell your doctor about any medicines you have taken. It might help to take the packaging along with you if you can.

Medicines

Treating mild to moderate P. falciparum malaria
There are three main treatments for mild to moderate P. falciparum malaria. All are equally effective.

The standard treatment for mild P. falciparum malaria in the UK is quinine tablets followed by a second medicine, which may be:

• doxycycline - for most adults.
• clindamycin - for pregnant women and children
• sulfadoxine with pyrimethamine (Fansidar)

Common side-effects of quinine include feeling sick and ringing in your ears (tinnitus), but these should stop when you stop taking it. Side-effects from the other medicines listed above can include skin rashes, tummy pain and fever.

Alternative medicines for mild P. falciparum malaria are artemether with lumefantrine (Riamet) or atovaquone with proguanil (Malarone). These treatments can also cause side-effects such as feeling sick, vomiting and abdominal pain but are generally given for a shorter time.

If you have P. falciparum malaria, you will usually need to stay in hospital for at least 24 hours for monitoring. This is because it can rapidly progress to a more severe infection.

Treating severe P. falciparum malaria
The standard treatment for severe P. falciparum malaria is quinine directly into your bloodstream (intravenous). Once you're well enough, you can have the rest of your treatment as tablets.

If you have severe P. falciparum malaria, you need to be monitored carefully and treated for any complications. The severity of malaria usually depends on the number of red blood cells infected with P. falciparum.

Treating other forms of malaria
The standard treatment for non-P. falciparum malaria is chloroquine tablets (eg Avloclor, Malarivon, Nivaquine). You can take chloroquine if you're pregnant. Side-effects of chloroquine can include vomiting, diarrhoea, tummy pains and itching.

If you have malaria caused by P. vivax and P. ovale, you will need longer-term treatment to stop the infection coming back, because parasites can stay in your liver. Primaquine is the usual medicine. Side-effects of primaquine can include vomiting, diarrhoea and tummy pains. It isn't suitable for everyone, for example you can't take it if you are pregnant.

If your illness is mild, you will probably be able to take your medicines at home. However, you will need to go to hospital if you develop complications or need medication through an intravenous drip.

Complementary medicines

There is no scientific proof that any herbal and homeopathic remedies can prevent or treat malaria and they aren't licensed for these uses. It may put you at risk if you rely on these remedies to prevent or treat malaria.

Special considerations

Acquired immunity

If you're born in a malarious area, you may develop immunity to the infection. But this only lasts for six to 12 months after you leave. After this, you will need to take antimalarial medicines if you return to a malarious area.

If you're pregnant

Complications of malaria are more likely if you are pregnant. Malaria in pregnancy is also associated with miscarriages or stillbirths.

If you have malaria and are pregnant, you will need to be treated with quinine. Evidence shows that quinine is safe in pregnancy, although it can increase the risk of low blood sugar and can cause labour. Your doctor will monitor you and your baby for any signs of complications. You may need to have your baby early if this is safest for you and your baby.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.