“…3,19 Most IHC tests use polyclonal anti-R rickettsii antibodies that will react with many different species of SFGR, including R rickettsii, R akari, R africae, R conorii, Rickettsia species 364D, and R parkeri, making the results of IHC studies insufficient for identifying the specific infecting agent. 3,5,6,18 Although IHC staining of the biopsy specimens from each of our patients showed evidence of infection with SFGR, specific identification of the infecting pathogen was not possible in 2 of the 3 cases because IHC stains are only SFGR specific ( Table 2). The acute and convalescent serologic tests are also only SFGR specific and have the same limitations as IHC staining.…”