malaria

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)

Reference:

• (1) Public Health England. Guidelines for malaria prevention in travellers from the UK 2019
• (2) Health protection agency. Malaria

Last edited 12/2019 and last reviewed 10/2020