title: Acquisition and subsequent transmission of Borrelia hermsii by the soft tick Ornithodoros hermsi.
abstract: Tick-borne relapsing fever is caused by spirochetes within the genus Borrelia. The hallmark of this disease is recurrent febrile episodes and high spirochete densities in mammalian blood resulting from immune evasion. Between episodes of spirochetemia when bacterial densities are low, it is unknown whether ticks can acquire the spirochetes, become colonized by the bacteria, and subsequently transmit the bacteria once they feed again. We addressed these questions by feeding ticks, Omnithodoros hermsi Wheeler (Acari: Argasidae),daily on an infected mouse during low andhigh levels of spirochete infections. This study demonstrates that spirochete acquisition by the tick vector can occur during low levels of mammalian infection and that once a spirochetemic threshold is attained within the blood, nearly 100% of ticks become colonized by Borrelia hermsii.
authors.affiliation: Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA. lopezjob@niaid.nih.gov
authors.forename: Job E
authors.initials: JE
authors.lastname: Lopez
authors.forename: Brandi N
authors.initials: BN
authors.lastname: Mccoy
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Krajacich
authors.forename: Tom G
authors.initials: TG
authors.lastname: Schwan
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology* / Q000502:physiology; D001769:Blood; D001898:Borrelia; D005247:Feeding Behavior; D005260:Female; D051379:Mice; D009758:Nymph; D026861:Ornithodoros / Q000382:microbiology* / Q000502:physiology; D012061:Relapsing Fever / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission*