Explanation

Plasmodium falciparum antigen: what is measured?

Plasmodium falciparum is the malaria parasite that causes the most severe form of the disease and is responsible for most of the cases reported in the Netherlands. The rapid test looks in a drop of blood for a protein (antigen) that this species makes, usually the protein HRP2. The test gives a result quickly and is part of the same examination as looking at a thick blood smear under the microscope, which according to the LCI guideline (RIVM) on malaria is the standard test and also shows how many red blood cells are infected.

What can it detect?

A current infection with Plasmodium falciparum, the species that can become life-threatening within a few days

Result

What does the result mean?

Positive result

A protein of Plasmodium falciparum was found, which fits a current infection. This form of malaria can quickly become severe: without treatment, severe anemia, kidney problems, breathing problems, or confusion and loss of consciousness can develop within a few days. The first symptoms usually appear from 7 days after the mosquito bite: fever, chills, headache, muscle pain and a flu-like feeling. The laboratory also examines a thick blood smear, because the share of infected red blood cells is taken into account when choosing the treatment. The HRP2 protein can remain detectable for a few weeks after successful treatment.

Negative result

No protein of Plasmodium falciparum was found. This does not rule out malaria. According to the LCI guideline (RIVM), depending on the region, the rapid test misses 10 to 40 and sometimes up to 80 in 100 cases of this species, partly because some strains do not make the HRP2 protein. Early in the illness, when there are few parasites in the blood, the test can also be negative. With fever after a stay in a malaria area, microscopic examination of a thick blood smear remains necessary, repeated if needed.

After an abnormal result

Fever during or after a stay in an area where malaria occurs is an emergency and should be assessed by a doctor the same day; you do not wait for the result of a self-ordered test. A negative rapid test does not rule out malaria: if the suspicion persists, microscopic examination of a thick blood smear follows, repeated after one to two days if needed. With a positive result, the doctor starts treatment as soon as possible and assesses whether hospital admission is needed. Malaria is notifiable (group C): a confirmed infection is reported to the GGD (municipal public health service) within one working day.

Reliability

How reliable is the test?

The rapid test is a quick addition to, and not a replacement for, the microscopic examination of a thick blood smear; according to the LCI guideline (RIVM) on malaria, the latter is the standard test. The rapid test is more sensitive for Plasmodium falciparum than for the other species, but the guideline states that, depending on geographic origin, 10 to 40 percent and sometimes up to 80 percent of cases are missed. A negative result should therefore not be used to rule out malaria. The test also says nothing about the share of infected red blood cells, while that determines the severity.

What can affect the result?

Strains of Plasmodium falciparum that do not make the HRP2 protein give a negative result, even with a severe infection.
Early in the illness, when there are few parasites in the blood, the test can be negative.
The HRP2 protein can remain detectable for weeks after successful treatment; a positive result then does not necessarily mean an active infection.
The test says nothing about the share of infected red blood cells; this is determined with microscopy and is taken into account when assessing severity.

Who it is for

Who is the test useful for?

Useful for

Intended for people with fever or flu-like symptoms during or shortly after a stay in an area where malaria occurs, especially sub-Saharan Africa. Symptoms caused by this species usually start from 7 days after the mosquito bite and almost always appear within a few months of returning. Without a stay in a malaria area, the test has no meaning.

How common is it?

Between 2014 and 2024, 72 to 343 cases of malaria were reported in the Netherlands each year; in 2023 there were 249 and in 2024 there were 217. About 90 in 100 reports concern an infection acquired in Africa, often during a visit to family or friends. Malaria is not transmitted in the Netherlands itself. Plasmodium falciparum is the main cause.

RIVM/LCI guideline on malaria (reports 2014 to 2024)

Drawbacks and risks

A negative rapid test can give false reassurance; with this species, delaying treatment can become life-threatening within a few days.
The HRP2 protein remains detectable for weeks after treatment, so a positive result can lead to unnecessary worry or unnecessary re-treatment.

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