The Weil-Felix test is carried out to diagnose rickettsial infections in a person’s body. It is an agglutination test carried out on a blood sample from the patient to detect any infections. The test detects presence of anti-rickettsial antibodies through cross-reactions occurring between the antibodies. Such antibodies are produced in acute rickettsial infections having OX antigens of Proteus species. The test can be carried in two different ways viz. slide method and tube method. The antigens required are available commercially.