Malaria Antigen (Rapid Test)
A quick finger-prick or blood-draw test that looks for proteins from malaria parasites. In the US, a positive or negative result is followed up with a blood smear.
AI-verified against cited sources. Awaiting expert reviewAlso called RDT, Malaria RDT, HRP2LOINC 70569-9
What it is
Malaria is caused by parasites that infect red blood cells and are passed on by mosquito bites. Rapid tests look for proteins (antigens) that the parasites release. They give an answer in about 15 minutes and do not need a skilled microscopist. Some tests can tell P. falciparum apart from other species, but they cannot name every species. The test cannot count parasites or tell how sick you are, so a blood smear is used to confirm the species and measure the amount.
Why it matters
Malaria can become life-threatening if it is not treated quickly, and the type of parasite affects which treatment is used. A rapid test gives an early answer and can point to P. falciparum, the type that can be most dangerous. But rapid tests miss some infections and can stay positive after treatment, so the CDC recommends following up every rapid test with a blood smear.
If it’s low
A negative result means no malaria antigen was found at the time of the test. It does not completely rule out malaria. Parasite numbers rise and fall over time, rapid tests are less sensitive than a microscope, and some P. falciparum parasites lack the protein the test looks for. If malaria is still suspected, clinicians usually repeat blood smears every 12 to 24 hours for a total of three sets.
Common causes
- You do not have malaria
- Very few parasites in the blood early in an infection
- A non-falciparum species, which rapid tests detect less reliably
- P. falciparum parasites that lack the protein the test targets (HRP2 or HRP3)
What can help
- If you have a fever after travel, ask about repeat testing even if the rapid test is negative
- Share your travel dates and destinations with your clinician
If it’s high
A positive result means proteins from malaria parasites were found in your blood. Your clinician will usually order a blood smear to confirm the species and count the parasites, and will usually start treatment right away. Rapid tests can stay positive for weeks after a successful treatment, so a positive result soon after treatment is not always a new infection.
Common causes
- A current malaria infection, usually from a mosquito bite in a place where malaria occurs
- Leftover antigen from a recently treated infection, which can stay detectable for weeks
- Rarely, malaria passed on by a blood transfusion, an organ transplant or shared needles
- A false-positive result, which is one reason a blood smear is done to confirm
What can help
- Ask for a blood smear to confirm the species and measure how many red blood cells are infected
- Tell your clinician exactly where and when you traveled in the past year
What can affect your result
- How many parasites are in the blood: very low numbers early in an infection can be missed
- Which species is present: tests are less sensitive for non-falciparum species
- Recent treatment: antigen can stay detectable for weeks
- Test brand: result categories and sensitivity differ between rapid tests
- Rapid tests can stay positive for weeks after effective treatment, because the antigen lingers (CDC).
- Rapid tests are less sensitive than microscopy, especially for non-falciparum species (CDC).
- Some P. falciparum parasites lack the HRP2 or HRP3 proteins that many rapid tests look for, which can cause a false negative (CDC).
- Very low parasite numbers early in an infection can be missed.
A rapid test shows what is in the blood at the moment of the draw. Antigen can remain detectable for weeks after treatment, so it is not used to check whether treatment worked.
When to talk to a clinician
Get medical care promptly for fever, chills, headache or body aches during or after travel to a place where malaria occurs, even months later. Symptoms usually start 7 to 30 days after a bite but can take up to a year. Call 911 or your local emergency number for confusion, seizures or loss of consciousness.
Questions you could ask
- Does my travel history change which tests I should have?
- Which species of malaria is it, and how many of my red blood cells are infected?
- Do I need to be treated in a hospital?
- Do the people I traveled with need to be checked?
- If my fever continues, when should we repeat testing?
- Should we look for other causes of fever after travel?
Questions people ask
Why do I need a blood smear if my rapid test is positive or negative?
A rapid test cannot count parasites or tell every species apart, and it is less sensitive than a microscope. The CDC recommends following every rapid test with microscopy to confirm the result, identify the species and measure how many red blood cells are infected.
Can the rapid test be negative if I really have malaria?
Yes, it can. Early in an infection there may be too few parasites, and some parasites lack the protein the test targets. If malaria is still suspected, the CDC advises repeating blood smears every 12 to 24 hours for a total of three sets.
Show the science and sources
For clinicians and researchers
Immunochromatographic rapid diagnostic tests (RDTs) detect parasite antigens in whole blood. Abbott's BinaxNOW Malaria is the only RDT FDA-approved for diagnostic use in the US (CDC). It targets P. falciparum histidine-rich protein II (HRP2) plus a pan-malarial antigen common to the four species it lists (P. falciparum, P. vivax, P. ovale, P. malariae), gives results in about 15 minutes, and uses venous or capillary EDTA whole blood. Abbott's published performance figures (manufacturer claims) list P. falciparum sensitivity of 99.7% (at parasitemia above 5,000 per microliter) with specificity of 94.2%, and P. vivax sensitivity of 93.5% (same threshold) with specificity of 99.8%. CDC states that the test is less sensitive than microscopy, especially for non-falciparum species, cannot confirm the species, determine parasitemia or monitor response to treatment, and may stay positive for weeks after effective treatment. Some P. falciparum parasites have HRP2 or HRP3 deletions, which can cause false negatives. CDC advises ordering microscopy at the same time to confirm both positive and negative RDT results, determine the species and calculate parasitemia. Other brands used worldwide (for example Pf/Pan or Pf/Pv formats) use different antigens, and their result categories differ.
LOINC 70569-9 (primary), 76772-3, 50687-3, 46094-9. Specimen: whole-blood.
Sources
- Evaluation and Diagnosis of Malaria, CDC
- Malaria Tests, MedlinePlus (NIH)
- BinaxNOW Malaria Test, Abbott
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.