One of the world’s most common diseases, malaria affects over 200 million people and causes up to three million deaths each year. Previously extremely widespread, the disease is now largely confined to Africa, Asia and Latin America.

Malaria is caused by protozoan parasites of the genus Plasmodium. There are four species of Plasmodium causing human malaria: P. falciparum, P. vivax, P. malariae and P. ovale. These parasites, which share their life cycle with mosquitoes, are injected into the human bloodstream by the bite of female Anopheles mosquitoes. Direct transmission from one human to another can also be caused via the transfusion of infected blood. Of the four species, P. falciparum is the most common and virulent strain, causing most malaria-related deaths worldwide. P. vivax is a particular problem in South-east Asia and South America.

In nonendemic areas, malaria is one of the most important imported diseases. For this reason most blood transfusion services have a policy of deferring ‘at-risk’ donors to minimise the risk of transfusion-transmitted infection. With the introduction of a suitable screening test Australia and the UK have retained between >40 000 and >60 000 donations annually by early re-admittance of donors.