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.

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.

• Suspect it regardless of whether they took prophylaxis.

• Suspect it 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.

• 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.

• Roughly 9 in 10 had taken no chemoprophylaxis.

In the surgery:

• Suspect it and arrange a same-day blood film.

• Recognise severe malaria and call 999.

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.

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. • 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

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