Weil-Felix test

The Weil-Felix test is a test for the presence and type of rickettsial disease based on the agglutination of OX-strains of Proteus vulgaris with suspected rickettsia in a patient's blood serum. It is a heterophile agglutinition reaction. The non-motile Proteus strains used are OX-2, OX-19, and OX-K.