Malaria is a parasitic disease caused by genus Plasmodium. The parasite is spread by female Anopheles mosquitoes and five species of Plasmodium regularly infect humans:
- P. falciparum - most dangerous form, accountable for majority of deaths throughout the world
- P. ovale - a relapsing malaria
- P. vivax - a relapsing malaria
- P. malariae - least common type present in UK, may present with late recrudescence after many years
- Plasmodium knowlesi - very rarely imported at present, but capable of producing severe illness
Mixed infections with more than 1 species of malaria parasite are not commonly reported (11 in 2017).
In recent years, the incidence of P. vivax in UK travellers has dropped, but in regions where it is a problem, the risk of acquiring vivax malaria is year round.
Plasmodium species that infect humans:
P. falciparum malaria is the most severe being characterised by paroxysms of chills, sweats and haemolysis. Cerebral malaria is a potentially fatal complication.
Protective factors against malaria include sickle cell trait; HLA-B53 positive (1).
Malaria may also be transmitted by blood transfusion and transplacentally. Another possible means of transmission is via so-called 'airport malaria' where infected mosquitoes have been transported by air.
Rarely malaria can occur in people without a travel history which is known as "cryptic" malaria (2).
Malaria is a statutorily notifiable disease in England and Wales (1).
It is not endemic in the UK (1,2)
- (1) Public Health England. Guidelines for malaria prevention in travellers from the UK 2019
- (2) Health protection agency. Malaria