title: Discovery of an enzootic cycle of Borrelia burgdorferi in Neotoma mexicana and Ixodes spinipalpis from northern Colorado, an area where Lyme disease is nonendemic.
abstract: An intensive enzootic cycle of Borrelia burgdorferi was seen in populations of the Mexican wood rat, Neotoma mexicana, and Ixodes spinipalpis ticks in northern Colorado. Cultures of rodent ear tissue and ticks yielded 63 spirochetal isolates: 38 N. mexicana, 2 Peromyscus difficilis, and 23 I. spinipalpis. All 63 isolates were identified as B. burgdorferi sensu lato by polymerase chain reaction; a representative subset was characterized as B. burgdorferi by SDS-PAGE and immunoblotting. A tick-derived spirochete isolate was infectious to laboratory mice and I. scapularis, the principal vector of Lyme disease in endemic areas of the United States. The risk of human contact with infected I. spinipalpis appears to be minimal from this epidemiologically silent focus in northern Colorado, since this tick is restricted to wood rat nests in this semiarid environment.
authors.affiliation: Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522.
authors.forename: G O
authors.initials: GO
authors.lastname: Maupin
authors.forename: K L
authors.initials: KL
authors.lastname: Gage
authors.forename: J
authors.initials: J
authors.lastname: Piesman
authors.forename: J
authors.initials: J
authors.lastname: Montenieri
authors.forename: S L
authors.initials: SL
authors.lastname: Sviat
authors.forename: L
authors.initials: L
authors.lastname: VanderZanden
authors.forename: C M
authors.initials: CM
authors.lastname: Happ
authors.forename: M
authors.initials: M
authors.lastname: Dolan
authors.forename: B J
authors.initials: BJ
authors.lastname: Johnson
mesh_terms: D000818:Animals; D015748:Borrelia burgdorferi Group / Q000302:isolation & purification* / Q000472:pathogenicity; D003120:Colorado; D004197:Disease Reservoirs; D004591:Electrophoresis, Polyacrylamide Gel; D005843:Geography; D006801:Humans; D015151:Immunoblotting; D008193:Lyme Disease / Q000453:epidemiology* / Q000635:transmission; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010542:Peromyscus / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012377:Rodentia / Q000382:microbiology*; D013987:Ticks / Q000382:microbiology*