Definition: Malaria is caused by a protozoan infection of red blood cells with one of four species
of the plasmodium: P falciparum, P vivax, P ovale, or P malariae. Clinically, malaria may present
in different ways, but it is usually characterised by fever (which may be swinging), tachycardia,
rigors, and sweating. Anaemia, hepatosplenomegaly, cerebral involvement, renal failure, and
shock may occur. Incidence/prevalence: Each year there are 300-500 million clinical cases of
malaria. About 40% of the world's population is at risk of acquiring the disease. Each year
25-30 million people from non-tropical countries visit areas in which malaria is endemic, of
whom between 10 000 and 30 000 contract malaria.
Aetiology/risk factors: Malaria is mainly a rural disease, requiring standing water nearby. It is
transmitted by bites from infected female anopheline mosquitoes, mainly at dusk and during
the night. In cities, mosquito bites are usually from female culicene mosquitoes, which are not
vectors of malaria. Malaria is resurgent in most tropical countries and the risk to travellers is
increasing.