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Malaria - the disease

Published by Bupa's health information team, June 2008.

This factsheet is for people who have malaria, or who would like information about it. For information on how to prevent getting malaria, see Related topics.

Malaria is an infectious disease mainly 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 being bitten by a mosquito carrying a type of parasite called Plasmodium.

About malaria
Causes
Symptoms
Complications
Diagnosis
Treatment
Special considerations
Further information
Questions and answers
Related topics
Sources

About malaria

There are two categories of malaria.

Malignant malaria causes symptoms straight away 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 and can cause relapses. This is caused by the other types of malaria parasite (for more information, see Causes).

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

Causes

Malaria is caused by infection with a parasite called Plasmodium that is transmitted by mosquitos.

Malaria parasite

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

P. falciparum is responsible for about three-quarters of reported malaria cases. Most of the other cases of malaria are caused by P. vivax with just a few caused by the other two species. It's possible to 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.

Symptoms

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

a headache
aching muscles
tummy ache
weakness or lack of energy

A day or so later, your temperature may rise (up to 40°C) and you may have:

a fever
shivers
mild chills
a severe headache
a loss of appetite
vomiting
diarrhoea

Your symptoms can appear any time after you are bitten by a mosquito carrying the malaria parasite (for more information, see Causes). However, it takes at least six days for symptoms to appear.

The time it takes your symptoms to appear can vary with the type of parasite that the mosquito was carrying.

If you are bitten by a mosquito carrying the P. falciparum parasite, symptoms usually appear within three months of being bitten.
If you are bitten by a mosquito carrying the P. vivax, P. ovale or P. malariae parasite, symptoms can appear a year or more after being bitten. 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

If you get infected with P. falciparum your malaria can progress to a more severe form (also called complicated malaria). You may have symptoms including:

low blood sugar levels
severe anaemia
jaundice
fluid on your lungs (pulmonary oedema)
acute respiratory distress syndrome
kidney failure
spontaneous bleeding
state of shock (circulatory collapse)
fits (convulsions)
paralysis
coma

Severe malaria can affect your brain and central nervous system and can be fatal.

Symptoms of severe malaria can appear within hours or days of your first symptoms of malaria. It's important to seek urgent medical advice if you suspect you have severe malaria.

Complications are likely to be more severe in pregnant women, children and the elderly.

Diagnosis

Your GP will ask you about your symptoms and examine you. He or she may also 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 GP 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

There are a number of medicines that are effective if you start taking them soon after your symptoms appear. Resistance to certain medicines is a growing problem, so your GP will ask you which region you have visited and take this into account.

Some of the medicines for malaria can also help prevent malaria. If you have taken a preventive antimalarial medicine you should not take the same medicine to treat malaria. You should tell your GP about any medicines you have taken.

Medicines

Treating mild 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.

Doxycycline - used for most adults.
Clindamycin - used for pregnant women and children.
Sulphadoxine with pyrimethamine (Fansidar) - only used in certain circumstances because resistance to this treatment is high.

When taking quinine, you may get side-effects such as feeling sick and tinnitus (ringing in the ears) but these should stop when you stop taking it. If you take a second medicine, you may rarely get side-effects including skin rashes, tummy pain and fever, which can be caused by the medicines listed above.

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

Treating severe P. falciparum malaria

If you have severe P. falciparum malaria you will probably be admitted to hospital for monitoring. This is because it can rapidly progress to a more severe infection.

The standard treatment for severe P. falciparum malaria is quinine directly into your bloodstream (intravenous). Once you are well enough you will then be given oral medication.

Patients with severe P. falciparum malaria require careful monitoring and treatment for any complications that arise.

Treating other forms of malaria

The standard treatment for non-P. falciparum forms of malaria is oral chloroquine (eg Avloclor). Chloroquine is considered safe if you are pregnant but can cause vomiting, diarrhoea, abdominal pain and itching.

If you have malaria caused by P. vivax and P. ovale, you will need longer-term treatment to prevent relapse of infection caused by parasites in your liver (for more information, see Parasite lifecycle). Primaquine is the usual treatment and the dose depends on where you caught malaria. Primaquine can cause vomiting, diarrhoea and abdominal pain. It isn't suitable for everyone, for example if you are pregnant. Your doctor will be able to tell you if it's appropriate and advise you of alternative medicines if necessary.

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

Complementary medicines

The Health Protection Agency advises that herbal remedies have not been tested for their ability to prevent or treat malaria and aren't licensed for these uses. Nor is there scientific proof that homeopathic remedies are effective in either preventing or treating malaria. You should visit your GP if you have an illness with a fever and have travelled to a malarious region within the last year.

Special considerations

Acquired immunity

You may develop an immunity to malaria if you live in a malarious area. However, this only lasts for a period of months after leaving that area. After this, you will need to take antimalarial medicines if you return to a malarious area, in order to prevent infection.

If you are 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. Quinine is advised because its side-effect profile in pregnancy is known. It's generally safe, although it can increase the risk of low blood sugar and may cause you to go into labour. Your doctor will monitor you and your baby for any signs of complications and where necessary, an early delivery may be considered if you are near term.

Further information

Department of Health
020 7210 4850
www.dh.gov.uk