The first report of a confirmed human case of infection with
R. parkeri was published in 2004. The person was infected in the state of Virginia in the United States. Terms used to describe human infection with
R. parkeri include "American boutonneuse fever" because of its similarity to
boutonneuse fever caused by
Rickettsia conorii; "
American tick bite fever" because of its similarity to
African tick bite fever caused by
Rickettsia africae; "Tidewater spotted fever," after the
Tidewater region in the eastern United States; and "
Rickettsia parkeri rickettsiosis" or "
R. parkeri rickettsiosis."
Diagnosis The CDC recommends
polymerase chain reaction (PCR) of a biopsy or swab of an eschar, or PCR of a biopsy of a rash, for diagnosis of
R. parkeri infection. In addition, indirect
immunofluorescence antibody (IFA) assays using paired acute and convalescent sera can be used.
Clinical manifestations A 2008 study compared 12
R. parkeri cases with 208
Rocky Mountain spotted fever cases caused by
R. rickettsii. Although both
R. parkeri and
R. rickettsii caused fever, rash, myalgia, and headache,
R. parkeri caused eschars and
R. rickettsii did not. Furthermore, the percentage of patients hospitalized was lower for
R. parkeri than for
R. rickettsii (33% vs 78%), and
R. parkeri led to no deaths while
R. rickettsii led to death in 7% of cases. A 2021
systematic review of 32 confirmed and 45 probable cases of human infection with
R. parkeri determined that 94% of the confirmed cases had fever, 91% an eschar, 72% a rash, 56% headache, and 56%
myalgia, with similar percentages among the probable cases. The rash was most frequently described as papular or macular. Among the confirmed and probable cases, the most common treatment was doxycycline, followed by
tetracycline. Although 9% of all the cases were hospitalized, there was a "100% rate of clinical recovery." ==History==