Weil Felix Test


Clinical definition of the Weil Felix test
The Weil-Felix test is a test for the diagnosis of typhus and certain other rickettsial infections. Rickettsia are bacteria that are carried by many ticks, fleas, lice and cause diseases in humans. Rickettsial disease encompasses a group of diseases caused by the microorganisms such as typhus, rickettsial pox, Boutonneuse fever, African tick bite fever, Rocky Mountain spotted fever, Australian Tick Typhus, Flinders Island Spotted Fever , Queensland tick typhus, Q fever, southern tick-associated rash illness (STARI), ehrlichiosis, and tularemia

Why is the Weil Felix test done?
This test is used to identify the presence of rickettsia and type of rickettsial disease without specifying a particular species.

What are the common signs/symptoms when the Weil Felix test is done?
Initial symptoms include:

  • Fever
  • Nausea
  • Vomiting
  • Severe headache
  • Muscle pain
  • Lack of appetite
  • Headache
  • Backache
  • Swelling of the parotid glands (behind the ear)

Later signs and symptoms include:

  • Skin lesions
  • Maculopapular rash
  • Petechial rash
  • Abdominal pain
  • Joint pain

Who should do the Weil Felix test (Target population)?
Persons showing the above signs & symptoms.

What should I do before the Weil Felix test?

Specimen type

Specimen collection procedure

Preparatory instructions before the test *

Serum (Blood Sample)

Venipuncture - Collection of blood from a vein, usually from the arm.

No Fasting Required.

No other special preparations required.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my Weil Felix test results?

Reference Range*


Slide or Tube Test: Titer of ≥ 1: 320


‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the Weil Felix test

  • Typhus
  • Rickettsial pox
  • Boutonneuse fever
  • African tick bite fever
  • Rocky mountain spotted fever
  • Australian tick typhus
  • Flinders island spotted fever
  • Queensland tick typhus
  • Q fever
  • Southern tick-associated rash illness (stari)
  • Ehrlichiosis
  • Tularemia

Other tests related to the Weil Felix test

  • Indirect Immunofluoresence Antibody (IFA)


Synonyms : Rickettsia test