Malaria is a tropical disease passed on to humans by mosquitoes, and is present in over 100 countries.

Malaria predominantly affects countries in Africa, south and central America, Asia, and the middle east. The disease is particularly widespread in sub-Saharan Africa, where over 90% of malaria-related deaths occur. There are a number of reasons for the geographic spread of malaria which are outlined below.

• Climate - the Anopheles mosquito species that carries the malaria disease lives in hot, humid climates. However, these mosquitoes cannot survive cold winters, so therefore areas with significant seasonal changes are less prone to malaria.
• Prevention and treatment - those living in developing countries may have poor access to preventative measures, treatments and medical supplies.
• Rural areas - people living in urban areas do not tend to get malaria as often as those who live in rural areas because they are less likely to come into contact with mosquitoes.
• Drainage - poorer drainage, in rural areas, also increases the risk of malaria as mosquitoes breed in stagnant water.

Almost two thirds of all cases of malaria-related deaths occur among the poorest 20% of the world's population.

In 1998, the World Health Organization (WHO), UNICEF, World Bank and the United Nations Development Program (UNDP), joined forces to fund the Roll Back Malaria program. Roll Back Malaria aims to halve malaria-related deaths by 2010.

There are two general types of malaria: benign and malignant. Benign malaria is milder and relatively easy to treat. Malignant malaria can be very severe, and is sometimes fatal. If malignant malaria is suspected, immediate medical attention is required.