Diversity of piroplasms detected in blood-fed and questing ticks from several states in the United States

作者：Shock Barbara C^*; Moncayo Abelardo; Cohen Sara; Mitchell Elizabeth A; Williamson Phillip C; Lopez Gaylord; Garrison Laurel E; Yabsley Michael J

来源：Ticks and Tick-Borne Diseases, 2014, 5(4): 373-380.

DOI：10.1016/j.ttbdis.2014.01.003

• Babesia
• Cytauxzoon
• Theileria
• Dermacentor variabilis
• Amblyomma americanum
• Tick-transmitted diseases

Piroplasms in the genera Babesia, Theileria, and Cytauxzoon are tick-borne parasites that may be animal and human pathogens. Most piroplasms with known life cycles are transmitted by ixodid ticks; however, for many species, the vector is unknown. This study was conducted to determine the prevalence and diversity of piroplasms in ticks from several US states. Piroplasm-specific polymerase chain reaction (PCR) assays were used to test 1631 ticks from Georgia (n = 486), Kentucky (n = 103), Pennsylvania (n = 1), Tennessee (n = 626), and Texas (n = 414). Ticks were either questing (n = 42) or collected from animals (n = 627) or humans (n = 962). The 2 primary species tested were Dermacentor variabilis (n = 702) and Amblyomma americanum (n = 743), but Amblyomma cajennense (n = 99), Amblyomma maculatum (n = 16), Ixodes scapularis (n = 4), I. woodi (n = 1), and unidentified Amblyomma spp. nymphs (n = 64) were also tested. A low prevalence of piroplasms was detected with 37 (2.3%), 35 (2.1%), and 9 (0.6%) ticks positive for Theileria spp., Babesia spp., or Cytauxzoon fells, respectively. Based on sequence analysis, at least 6 Babesia spp. were detected and 15 of the 35 (41%) Babesia-positive ticks were A. americanum, 19 (56%) were D. variabilis, and one (3%) was an I. scapularis. Nine Babesia-positive ticks were removed from humans from Kentucky (n = 1), Georgia (n = 2), Texas (n = 5), and Pennsylvania (n = 1). Three Babesia-positive ticks were questing A americanum which represents the first report of Babesia-infected questing Amblyomma in the US. Theileria infections were only detected in A. americanum, and all sequences were similar to white-tailed deer associated Theileria spp. C. felis was only detected in D. variabilis. These data suggest that A. americanum may be a vector of Babesia spp., although experimental studies are needed to confirm vector competence. Finally, these data demonstrate a high diversity of piroplasms in both questing and partially fed ticks in the US; although, host-blood meals can be present in non-questing ticks.

• 出版日期2014