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Malaria (Plasmodium falciparum, vivax, ovale, malariae, knowlesi)
Fever after travel to a malaria area is malaria until proven otherwise — get it checked today, not tomorrow.
Also known as: malaria · marsh fever · falciparum malaria · plasmodium infection · fever in the returning traveller
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
Malaria is caused by single-celled parasites, the plasmodia, transmitted by the night-time bite of the Anopheles mosquito. Hundreds of millions of people fall ill worldwide each year; Switzerland sees a few hundred cases annually, almost all after travel, most often to sub-Saharan Africa. The most important sentence first: fever after a stay in a malaria area is malaria until proven otherwise and must be investigated immediately — even months after returning. Falciparum malaria can become life-threatening within hours. The symptoms are unspecific and are often mistaken for flu: fever, chills, headache and aching limbs, nausea, diarrhoea, exhaustion. The textbook fever in a fixed rhythm is usually absent in precisely the most dangerous form. Diagnosis uses a blood smear under the microscope and a rapid test; a negative test does not rule malaria out and is repeated after twenty-four hours, over several days if suspicion remains. Treatment is medical and depends on the parasite species, the country visited and the severity. Prevention means combining measures: mosquito protection in the evening and at night, because Anopheles bites after dark, an impregnated bed net, long light-coloured clothing, an effective repellent on the skin — and, depending on the region, drug prophylaxis decided in a travel medicine consultation before departure. For travellers it is the drug prophylaxis that is decided in the consultation — matched to the region, the length of the trip and personal tolerance. Herbal remedies have not been studied as malaria prophylaxis. The fever most often appears within the first four months after the return; for two of the parasites, more than twelve months is also possible.
See a doctor or emergency department the same day and actively mention the trip — even if it was months ago. Do not wait until tomorrow.
Four to six weeks ahead. There it is decided, based on country, season, route and health, whether prophylaxis is needed.
Anopheles bites at dusk and through the night. Those are the hours that decide protection, not the afternoon by the pool.
No holes, tucked under the mattress. Where air conditioning or window screens are missing, this is the single best night-time protection.
Light, loose long-sleeved clothing in the evening, repellent on all exposed skin, applied after sunscreen and reapplied regularly.
It only works if taken without gaps, including the specified days after returning. The travel clinic settles the details.
Which agent fits depends on the destination and is settled in the travel medicine consultation. Herbal remedies have not been studied for this purpose.
Note country and dates and mention them at every medical visit in the following year. That detail often points the way faster than any test.
A single negative smear rules nothing out. With fever after a malaria area it is repeated after twenty-four hours, until three are negative.
Prophylaxis kills no mosquitoes — it kills the parasites transmitted despite protection, and so must be continued after returning: atovaquone-proguanil for seven days, doxycycline and mefloquine for four weeks. Stopping on landing is the most common mistake. No drug protects completely; the net and evening cover stay part of the protection. Fever after a tropical stay counts as malaria until proven otherwise — for up to a year afterwards.
The dangerous form usually breaks out seven to thirty days after the bite, but with incomplete prophylaxis can come months later; other forms up to a year and beyond. A rapid test and a blood film settle it within hours — and with suspicion one does not wait until morning, because the state can change within a day. The parasite multiplies in cycles of forty-eight or seventy-two hours; hence the fever pattern that gave intermittent fever its name.
Any fever from day seven in a malaria area and up to months after return counts as malaria until proven otherwise.
Headache and aching limbs, chills, weariness. It is this very resemblance that gets malaria recognised too late.
Nausea, vomiting, belly pain and diarrhoea are common. The regular alternating fever from the textbooks is often absent entirely.
When many red cells are destroyed, anaemia, a yellowish look and dark urine appear — a sign of a severe course.
These point to severe malaria and mean immediate hospital admission. Do not wait, call 144.
Early on there may be too few parasites in the blood. If suspicion remains, the test is repeated after twenty-four hours.
The proof is made under the microscope, in a stained blood film. With a suspicion a negative result is repeated after twenty-four hours — negative once does not mean ruled out.
Low platelets with fever after a stay in the tropics are one of the most reliable early hints of all.
Low blood sugar is among the dangerous companions of a severe course, especially in children and in pregnancy.
Rises through the breakdown of red cells. Yellow eyes with fever after the tropics are a sign of a severe course and tolerate no delay.
Fever, sweating and faster breathing clearly raise the need. Drinking enough keeps the mucus thin and the circulation steady — in children and older people it is the most important point of all.
Where blood is lost regularly the store empties long before the haemoglobin falls. Ferritin shows this earlier than the blood count — and refilling takes months, not weeks.
With low levels airway infections occur somewhat more often; correcting a deficiency makes sense, a high single dose during the infection does not act on it.
Clearly improves the uptake of plant iron. A glass of orange juice or some pepper with the iron-rich meal does more than the choice of preparation.
Needed by the defence cells. For lozenges at the start of a cold there are hints of a slightly shortened duration; at a high dose over months zinc lowers copper.
Clearly effective with proven deficiency, useless without. Take only with a documented deficiency — excess is harmful.
Clearly worthwhile and well studied when deficient; fewer data for the wider uses. Fat-soluble — check blood levels at high doses.
In the severe form low blood sugar is one of the most dangerous accompaniments — especially in children and in pregnancy, and further worsened by quinine. This is why the sugar is measured closely there.
The anaemia arises twice over: the pathogen destroys red cells, and the inflammation at the same time dampens their formation. This is why the blood count recovers more slowly after treatment than one expects.
In pregnancy malaria runs more severely, and the placenta is a favoured site for the pathogen. That is the reason travel to malaria areas is advised against in this time.
During an attack blood sugar can fall, especially in children. Enough fluid and regular small meals belong to the treatment — the antimalarials remain the main thing.
No food and no supplement protects against malaria. With fever after a stay in the tropics assessment counts in hours, not days — that comes before anything else.
AWMF 042-001 · S1 · 2025-09 — in force
Diagnostik und Therapie der Malaria
checked 2026-09