The malaria parasite is a microscopic organism called a Plasmodium and it belongs to the group of tiny organisms known as protozoans. There are four types of plasmodium: P. falciparum (the most dangerous), P. vivax, P. ovale and P. malariae. The species of mosquito that carries the malaria parasites is the Anopheles mosquito.

These parasites enter the host's bloodstream when bitten by an infected mosquito and then migrate to the liver where they multiply before returning back into the bloodstream to invade the red blood cells. The parasites continue to multiply inside the red cells until they burst releasing large numbers of free parasites into the blood plasma causing the characteristic fever associated with the disease. This phase of the disease occurs in cycles of approximately 48 hours.

The free parasites are then able to infect any mosquito that feeds on the host's blood during this phase. The cycle then continues as the parasites multiply inside the mosquito and eventually invade its salivary glands. (see the plasmodium life cycle below).

Malaria occurs in over 100 countries and more than 40% of the people in the world are at risk. Large areas of Central and South America, Hispaniola (Haiti and the Dominican Republic), Africa, the Middle East, the Indian subcontinent, Southeast Asia, and Oceania are considered malaria-risk areas.

The World Health Organisation estimates that each year 300-500 million cases of malaria occur worldwide and more than two million people die of malaria.

Symptoms of malaria include fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhoea may also occur. Malaria may cause anaemia and jaundice (yellow colouring of the skin and eyes) because of the loss of red blood cells. Infection with one type of malaria, P. falciparum, if not promptly treated, may cause kidney failure, seizures, mental confusion, coma, and death.

For most people, symptoms begin 10 days to 4 weeks after infection, although a person may feel ill as early as 8 days or up to 1 year later. Two kinds of malaria, P. vivax and P. ovale, can relapse; some parasites can rest in the liver for several months up to 4 years after a person is bitten by an infected mosquito . When these parasites come out of hibernation and begin invading red blood cells, the person will become sick.

Any traveller who becomes ill with a fever or flu-like illness while travelling and up to one year after returning home should immediately seek professional medical care. You should tell your GP that you have been travelling in a malaria-risk area.

Malaria can be cured with prescription drugs. The type of drugs and length of treatment depend on which kind of malaria is diagnosed, where the patient was infected, the age of the patient, and how severely ill the patient was at start of treatment.