Malaria & Malaria prophylaxis

🔍 When to Suspect

A febrile illness with fever, sweats, chills, headache, and malaise in anyone who has travelled to a malaria-endemic area, up to a year or more after return

From the full topic in The Ocean Library: Malaria & Malaria prophylaxis

🧭 When to suspect

Malaria is a parasitic infection caused by Plasmodium species and transmitted by the bite of the female Anopheles mosquito. It is not acquired in the UK – every case is travel-associated, so the diagnosis begins and ends with a travel history. Five species infect humans, but P. falciparum accounts for around three-quarters of UK cases and is the one that kills, capable of progressing to cerebral and multi-organ disease and to death within 24 hours of the first symptom.

Suspect malaria in anyone with a fever, or a history of fever, who has returned from or previously visited a malaria-endemic area in the past year – regardless of whether they took prophylaxis, and even if their temperature is normal when you see them. The shortest incubation is 6 days; most falciparum presents within 3 months and almost all within 6 months, while P. vivax and P. ovale can relapse a year or more after travel.

This matters because malaria is common and rising: there were 2,106 UK cases and 6 deaths in 2023 – the highest total since 2001. Around three-quarters occurred in people visiting friends and relatives (VFR) in their country of origin, and roughly 9 in 10 had taken no chemoprophylaxis. The two primary-care skills are simple: suspect it and arrange a same-day blood film, and recognise severe malaria and call 999.

Species	Key features	UK relevance
P. falciparum	Severe, rapidly progressive; cerebral and multi-organ disease; can be fatal	~75% of cases; mainly West Africa; usually presents < 3 months
P. vivax	Relapsing (dormant liver stages); rarely fatal but can be severe	Mainly South Asia; may present > 1 year later
P. ovale	Relapsing (dormant liver stages); generally milder	Mainly West Africa; may present > 1 year later
P. malariae	Indolent; quartan fever; chronic nephropathy reported	Least common; can present many years after exposure
P. knowlesi	Zoonotic (macaques); can be severe and rapidly progressive	Rare import from Southeast Asia

🧠 Clinical pearl The typical UK malaria death is not an unlucky backpacker but a traveller of African or South Asian heritage visiting family, who took no prophylaxis because they grew up in the area and "never got ill there". Childhood semi-immunity wanes within 1–2 years of leaving an endemic country, so returning VFR travellers are fully susceptible again – and may under-perceive their risk. Target prevention advice at exactly this group.

Source: UKHSA Malaria Prevention Guidelines · UK malaria treatment guidelines 2016 · NaTHNaC

---