Malaria is caused by parasites, usually spread through bites from infected mosquitoes. Fever, chills and headache can occur, but these symptoms also have other causes. A health professional should assess suspected malaria and arrange parasite-based testing rather than assuming every fever is malaria. Prevention includes insecticide-treated nets and other measures that reduce mosquito exposure. Prompt assessment and appropriate treatment help prevent severe illness. Confusion, convulsions or breathing difficulty requires immediate emergency care; these examples are not exhaustive. The treated-net and traveller articles explain different prevention contexts. This overview does not select a medicine, prescribe a dose or interpret an individual test result.