Rickettsial infections:

Clinical evidence¹ of infection and lab confirmation using:

• Serological evidence of a fourfold change in IgG titer reactive with Rickettsia² antigen by indirect immunofluorescence assay (IFA) between paired serum specimens (one taken in the first week of illness and a second 2-4 weeks later)
  
  OR
• Detection of Rickettsia² nucleic acid in a clinical specimen via amplification of a specific target by PCR assay
  
  OR
• Demonstration of Rickettsia² antigen in a biopsy or autopsy specimen by IHC
  
  OR
• Isolation of Rickettsia² from a clinical specimen in cell culture.

¹ Clinical evidence: Any reported fever and one or more of the following: rash, headache, myalgia, anemia, thrombocytopenia, or any hepatic transaminase elevation.

² Rickettsial infections include Rickettsia typhi (Typhus), Rickettsia rickettsia (Rocky Mountain Spotted Fever), Ehrlichia sp.  (Ehrlichiosis) and Anaplasma phagocytophilum (Anaplasmosis)