Volume 94, Issue 6
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Rocky Mountain spotted fever is the most common tick-borne disease in Tennessee. However, has rarely been isolated from endemic ticks, suggesting rickettsioses may be caused by other species. A total of 56 human serum samples that were serologically positive for exposure to were obtained from commercial laboratories in 2010 and 2011. In addition, 20 paired sera from patients with encephalitis and positive serology were obtained from the Tennessee Unexplained Encephalitis Surveillance (TUES) study. Using an immunofluorescence assay, reactivity of the sera to , , , and was tested, and a comparison of endpoint titers was used to determine the probable antigen that stimulated the antibody response. Cross-absorption was conducted for 94.8% ( = 91) of the samples due to serologic cross-reactivity. Of the commercial laboratory samples, 55.4% ( = 31) had specific reactivity to and 44.6% ( = 25) were indeterminate. Of the paired TUES samples, 20% ( = 4) had specific reactivity to , 5% ( = 1) to , and 5% ( = 1) to . Patients with specific reactivity to experienced fever (75%), headache (68%) and myalgia (58%). Rash (36%) and thrombocytopenia (40%) were less common. To our knowledge, this is the first time has been reported as a possible causative agent of rickettsioses in Tennessee.


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  • Received : 18 May 2015
  • Accepted : 13 Jan 2016
  • Published online : 01 Jun 2016

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