Weil-Felix test
Quick answer: The Weil-Felix test is an older blood test that checks for antibodies that react in rickettsial infections such as scrub typhus. Doctors may order it when a rickettsial fever is suspected and newer tests are not available.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
How the test is done
- 1A nurse confirms your details
- 2A vein on your arm is cleaned
- 3A needle collects a tube of blood
- 4The lab mixes your serum with Proteus bacteria and looks for clumping
What your results can mean
Reading your report
It can be falsely positive or negative, so your doctor reads it with your symptoms and other tests.
If the result is outside the usual range
A raised titre, especially against OX-K, can suggest scrub typhus, and against OX-2 or OX-19 other rickettsial fevers. False positives and negatives are common, so newer tests are preferred where available.
Who usually has this test
People with fever, rash or an eschar when rickettsial infection is suspected and specific tests are not available.
Risks and aftercare
The needle site may be tender for a day; there is no other aftercare.
Names and options
Also called: Weil Felix, rickettsial test
Listed by the hospital as
- WEIL FELIX TEST, SERUM
Questions about this test
Why is the Weil-Felix test called outdated?
It relies on a cross-reaction with unrelated bacteria, so it can miss infections or give false positives. Specific IgM tests are more reliable.
What do OX-K, OX-2 and OX-19 mean?
They are strains of Proteus bacteria used in the test. Different rickettsial infections react with different strains.
Can a single Weil-Felix test confirm infection?
A single result is weak evidence. A rising titre between two samples is more meaningful, and doctors usually also treat based on symptoms.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.