Malaria is a common and serious tropical disease caused by a type of parasite (protozoan) transmitted to human beings by biting mosquitoes. There are four kinds of malaria that can infect humans: Plasmodium falciparum, P. vivax, P. ovale, and P. malariae.
Malaria is a public health problem in more than 100 countries; over 2 billion people live in malarious parts of the world. More than 90% of cases occur in tropical Africa, but it is also found in the Indian subcontinent, Southeast Asia, Central and South America, Hispaniola (Haiti and the Dominican Republic), the Middle East, and Oceania. For travellers and tourists, Africa south of the Sahara probably represents the area of greatest risk of malaria.