title: Rickettsia parkeri and "Candidatus Rickettsia andeanae" in Questing Amblyomma maculatum (Acari: Ixodidae) From Mississippi.
abstract: Amblyomma maculatum Koch (Acari: Ixodidae), the primary vector for Rickettsia parkeri, may also be infected with a rickettsia of unknown pathogenicity, "Candidatus Rickettsia andeanae." Infection rates with these rickettsiae vary geographically, and coinfected ticks have been reported. In this study, infection rates of R. parkeri and "Ca. R. andeanae" were evaluated, and rickettsial DNA levels quantified, in 335 questing adult A. maculatum collected in 2013 (n = 95), 2014 (n = 139), and 2015 (n = 101) from Oktibbeha County, MS. Overall infection rates of R. parkeri and "Ca. R. andeanae" were 28.7% and 9.3%, respectively, with three additional A. maculatum (0.9%) coinfected. While R. parkeri-infected ticks were detected all three years (34.7% in 2013; 13.7% in 2014; 43.6% in 2015), "Ca. R. andeanae" was not detected in 2013, and was detected at rates of 10.8% in 2014, and 15.8% in 2015. Interestingly, rickettsial DNA levels in singly-infected ticks were significantly lower in "Ca. R. andeanae"-infected ticks compared to R. parkeri-infected ticks (P < 0.0001). Thus, both infection rates and rickettsial DNA levels were higher for R. parkeri than "Ca. R. andeanae." Infection rates of R. parkeri were also higher, and "Ca. R. andeanae" lower, here compared to A. maculatum reported previously in Kansas and Oklahoma. As we continue to monitor infection rates and levels, we anticipate that understanding temporal changes will improve our awareness of human risk for spotted fever rickettsioses. Further, these data may lead to additional studies to evaluate potential interactions among sympatric Rickettsia species in A. maculatum at the population level.
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: J K
authors: JK
authors: Lee
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: G M
authors: GM
authors: Moraru
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: J V
authors: JV
authors: Stokes
authors: Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (wills@cvm.msstate.edu).
authors: R W
authors: RW
authors: Wills
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: E
authors: E
authors: Mitchell
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: E
authors: E
authors: Unz
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: B
authors: B
authors: Moore-Henderson
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: A B
authors: AB
authors: Harper
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, 240 Wise Center Dr., Mississippi State, MS 39762 (klee@cvm.msstate.edu; gmoraru@cvm.msstate.edu; jstokes@cvm.msstate.edu; esm114@msstate.edu; eru1@msstate.edu; bsm136@msstate.edu; anb425@msstate.edu; stokes@cvm.msstate.edu).
authors: A S
authors: AS
authors: Varela-Stokes
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology* / Q000502:physiology; D006801:Humans; D026863:Ixodidae / Q000382:microbiology* / Q000502:physiology; D008922:Mississippi; D012281:Rickettsia / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D012282:Rickettsia Infections / Q000382:microbiology / Q000635:transmission*
keywords: Amblyomma maculatum (Gulf Coast tick); Mississippi; Rickettsia parkeri; “Candidatus Rickettsia andeanae”