Malaria Dr Trisha Macnair Are you aware of the symptoms of one of the world's biggest killers? As travel increases to destinations where malaria occurs, it's important to take preventive measures and be alert to symptoms once you return.

In this article

What is it? What are the symptoms?

Who's affected? How can I prevent it?

Malaria is caused by an infection of the red blood cells with a tiny organism or parasite called a protozoa. There are four important species of the malaria protozoa (Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae) and each has a slightly different effect.

These organisms are carried from person to person by the Anopheles mosquito. When it bites an infected person, the mosquito sucks up blood containing the parasite, which may then be passed on to the mosquito's next victim.

The main symptom of malaria is a fever that occurs in regular episodes, with sweating and shivers (known as rigors), and exhaustion (because of anaemia). In some cases, it can affect the brain or kidneys.

Malaria occurs where the Anopheles mosquito breeds, predominantly in rural tropical areas. From a UK perspective, it's a threat to people travelling to malarial regions in Africa, the Middle East, Asia and central America.

Each year about 2,000 people return to the UK with malaria, and approximately 12 people a year die as a consequence of the disease.

Malaria is a major killer in many countries where resources for prevention, proper diagnosis and drug treatments are lacking. If diagnosed promptly, it can be easily treated but the symptoms can be vague and UK doctors may not immediately be thinking about tropical infections.

About 90 per cent of travellers who contract malaria do not become ill until after they return home. Only about 12 per cent of these will become seriously ill.

On average, symptoms develop ten days to four weeks after being bitten, but symptoms can appear up to a year later.

The most severe form of the disease is cerebral malaria, which is fatal in up to six per cent of adults, mainly because it's not diagnosed until it's too late.

Don't make the mistake of assuming you're safe from infection if you have previously lived in a malarial region - you may build up some immunity to the disease but this can be lost quickly. And if your children were born in the UK, they'll have no immunity at all.

If you're going to visit, travel through, or even just stop over in a malarial country you'll be at risk, even if you have lived there before.

By far the most important step is to avoid being bitten by mosquitoes by:

• Using effective insect repellent
• Wearing long sleeves and full-length trousers
• Staying in accommodation with screen doors and closing windows

Before you travel, check whether your holiday destination is affected by malaria. You can find your destination on the Scottish Centre for Infection & Environmental Health website.

Take the recommended antimalarial drugs. Generally speaking, these are taken from one week before you travel until one month after you return, but this can vary depending on the type of drug and the country you're visiting.

Even when taken exactly as advised, antimalarial drugs are not 100 per cent effective, so you should still take the other preventive measures listed above.

A major problem is the steady increase in malaria's resistance to drugs used in both prevention and treatment. Always talk to your doctor if you are worried - don't just stop taking antimalarials without getting medical advice.

If you develop symptoms, get help quickly - and don't forget to tell the doctor you've travelled to a malarial area.

Treatment is with antimalarial medication.

In the past decade, considerable progress has been made in the search for a malaria vaccine, and it's hoped one will be available within the next five to ten years.

This article was last medically reviewed by Dr Rob Hicks in May 2008