title: Human Infections by Multiple Spotted Fever Group Rickettsiae in Tennessee.
abstract: Rocky Mountain spotted fever is the most common tick-borne disease in Tennessee. However, Rickettsia rickettsii 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 Rickettsia were obtained from commercial laboratories in 2010 and 2011. In addition, 20 paired sera from patients with encephalitis and positive Rickettsia serology were obtained from the Tennessee Unexplained Encephalitis Surveillance (TUES) study. Using an immunofluorescence assay, reactivity of the sera to R. rickettsii, Rickettsia montanensis, Rickettsia parkeri, and Rickettsia amblyommii 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% (N = 91) of the samples due to serologic cross-reactivity. Of the commercial laboratory samples, 55.4% (N = 31) had specific reactivity to R. amblyommii and 44.6% (N = 25) were indeterminate. Of the paired TUES samples, 20% (N = 4) had specific reactivity to R. amblyommii, 5% (N = 1) to R. montanensis, and 5% (N = 1) to R. parkeri Patients with specific reactivity to R. amblyommii experienced fever (75%), headache (68%) and myalgia (58%). Rash (36%) and thrombocytopenia (40%) were less common. To our knowledge, this is the first time R. amblyommii has been reported as a possible causative agent of rickettsioses in Tennessee.
authors.affiliation: Vector-Borne Diseases Section, Communicable and Environmental Diseases, Tennessee Department of Health, Nashville, Tennessee; Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas; Departments of Medicine and Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: Josie
authors.initials: J
authors.lastname: Delisle
authors.affiliation: Vector-Borne Diseases Section, Communicable and Environmental Diseases, Tennessee Department of Health, Nashville, Tennessee; Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas; Departments of Medicine and Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Mendell
authors.affiliation: Vector-Borne Diseases Section, Communicable and Environmental Diseases, Tennessee Department of Health, Nashville, Tennessee; Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas; Departments of Medicine and Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: Annica
authors.initials: A
authors.lastname: Stull-Lane
authors.affiliation: Vector-Borne Diseases Section, Communicable and Environmental Diseases, Tennessee Department of Health, Nashville, Tennessee; Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas; Departments of Medicine and Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: Karen C
authors.initials: KC
authors.lastname: Bloch
authors.affiliation: Vector-Borne Diseases Section, Communicable and Environmental Diseases, Tennessee Department of Health, Nashville, Tennessee; Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas; Departments of Medicine and Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: Donald H
authors.initials: DH
authors.lastname: Bouyer
authors.affiliation: Vector-Borne Diseases Section, Communicable and Environmental Diseases, Tennessee Department of Health, Nashville, Tennessee; Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas; Departments of Medicine and Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee abelardo.moncayo@tn.gov.
authors.forename: Abelardo C
authors.initials: AC
authors.lastname: Moncayo
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D003429:Cross Reactions; D006801:Humans; D012281:Rickettsia / Q000145:classification* / Q000276:immunology*; D012282:Rickettsia Infections / Q000097:blood / Q000453:epidemiology* / Q000382:microbiology*; D016036:Seroepidemiologic Studies; D013045:Species Specificity; D013714:Tennessee / Q000453:epidemiology
chemical_list: D000907:Antibodies, Bacterial