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Tick-borne relapsing fever and Borrelia hermsii, Los Angeles County, California, USA.

Schwan TG, Raffel SJ, Schrumpf ME, Schrumpf ME, Webster LS, Marques AR, Spano R, Rood M, Burns J, Hu R - Emerging Infect. Dis. (2009)

Bottom Line: The primary cause of tick-borne relapsing fever in western North America is Borrelia hermsii, a rodent-associated spirochete transmitted by the fast-feeding soft tick Ornithodoros hermsi.The patient's convalescent-phase serum was seropositive for B. hermsii but negative for several other vector-borne bacterial pathogens.We determined that this tick-borne disease is endemic to the San Gabriel Mountains near the greater Los Angeles metropolitan area.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA.

ABSTRACT
The primary cause of tick-borne relapsing fever in western North America is Borrelia hermsii, a rodent-associated spirochete transmitted by the fast-feeding soft tick Ornithodoros hermsi. We describe a patient who had an illness consistent with relapsing fever after exposure in the mountains near Los Angeles, California, USA. The patient's convalescent-phase serum was seropositive for B. hermsii but negative for several other vector-borne bacterial pathogens. Investigations at the exposure site showed the presence of O. hermsi ticks infected with B. hermsii and the presence of rodents that were seropositive for the spirochete. We determined that this tick-borne disease is endemic to the San Gabriel Mountains near the greater Los Angeles metropolitan area.

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Related in: MedlinePlus

Borrelia hermsii MTW-2 in mouse blood (Wright-Giemsa stain) viewed at 600× oil immersion. Scale bar = 40 μm.
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Figure 2: Borrelia hermsii MTW-2 in mouse blood (Wright-Giemsa stain) viewed at 600× oil immersion. Scale bar = 40 μm.

Mentions: The 3 nymphal O. hermsi ticks collected on June 14, 2007, and May 15, 2008, each fed on mice (Figure 1) and transmitted spirochetes that produced high spirochetemias (Figure 2). These spirochetes bound both monoclonal antibodies, which identified the spirochetes as B. hermsii (data not shown). Spirochetes grew to high cell density in BSK-H medium, and DNA was purified from the second–passage, 100-mL cultures (23) and designated MTW-2, MTW-3, and MTW-4. DNA samples purified from the cultures were subjected to PCR, and DNA sequences of the amplicons were determined for the same 6 loci (GenBank accession nos. EU194843, EU194845, EU194846, EU194847, EU203148, and EU203150). All sequences determined for each locus were identical for the 3 isolates. Sequences for the 16S rRNA, flaB, and gyrB genes and for the IGS locus were identical to those sequences for MTW-1. This similarity identified MTW-2, MTW-3, and MTW-4 as B. hermsii belonging to GG II. The glpQ sequences for MTW-1 and for MTW-2, MTW-3, and MTW-4 contained 2 synonymous base differences (99.8% identity). However, the vtp DNA sequence for MTW-2, MTW-3, and MTW-4 were identical and unique from all other vtp sequences in the database (18), although the sequences showed similarities with other Vtp type 5 sequences with 94.6% identity (18). The vtp sequences in MTW-1 and MTW-2 represented different Vtp types (type 6 and 5, respectively) and shared only 78.5% DNA and 69.3% amino acid identities.


Tick-borne relapsing fever and Borrelia hermsii, Los Angeles County, California, USA.

Schwan TG, Raffel SJ, Schrumpf ME, Schrumpf ME, Webster LS, Marques AR, Spano R, Rood M, Burns J, Hu R - Emerging Infect. Dis. (2009)

Borrelia hermsii MTW-2 in mouse blood (Wright-Giemsa stain) viewed at 600× oil immersion. Scale bar = 40 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2744237&req=5

Figure 2: Borrelia hermsii MTW-2 in mouse blood (Wright-Giemsa stain) viewed at 600× oil immersion. Scale bar = 40 μm.
Mentions: The 3 nymphal O. hermsi ticks collected on June 14, 2007, and May 15, 2008, each fed on mice (Figure 1) and transmitted spirochetes that produced high spirochetemias (Figure 2). These spirochetes bound both monoclonal antibodies, which identified the spirochetes as B. hermsii (data not shown). Spirochetes grew to high cell density in BSK-H medium, and DNA was purified from the second–passage, 100-mL cultures (23) and designated MTW-2, MTW-3, and MTW-4. DNA samples purified from the cultures were subjected to PCR, and DNA sequences of the amplicons were determined for the same 6 loci (GenBank accession nos. EU194843, EU194845, EU194846, EU194847, EU203148, and EU203150). All sequences determined for each locus were identical for the 3 isolates. Sequences for the 16S rRNA, flaB, and gyrB genes and for the IGS locus were identical to those sequences for MTW-1. This similarity identified MTW-2, MTW-3, and MTW-4 as B. hermsii belonging to GG II. The glpQ sequences for MTW-1 and for MTW-2, MTW-3, and MTW-4 contained 2 synonymous base differences (99.8% identity). However, the vtp DNA sequence for MTW-2, MTW-3, and MTW-4 were identical and unique from all other vtp sequences in the database (18), although the sequences showed similarities with other Vtp type 5 sequences with 94.6% identity (18). The vtp sequences in MTW-1 and MTW-2 represented different Vtp types (type 6 and 5, respectively) and shared only 78.5% DNA and 69.3% amino acid identities.

Bottom Line: The primary cause of tick-borne relapsing fever in western North America is Borrelia hermsii, a rodent-associated spirochete transmitted by the fast-feeding soft tick Ornithodoros hermsi.The patient's convalescent-phase serum was seropositive for B. hermsii but negative for several other vector-borne bacterial pathogens.We determined that this tick-borne disease is endemic to the San Gabriel Mountains near the greater Los Angeles metropolitan area.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA.

ABSTRACT
The primary cause of tick-borne relapsing fever in western North America is Borrelia hermsii, a rodent-associated spirochete transmitted by the fast-feeding soft tick Ornithodoros hermsi. We describe a patient who had an illness consistent with relapsing fever after exposure in the mountains near Los Angeles, California, USA. The patient's convalescent-phase serum was seropositive for B. hermsii but negative for several other vector-borne bacterial pathogens. Investigations at the exposure site showed the presence of O. hermsi ticks infected with B. hermsii and the presence of rodents that were seropositive for the spirochete. We determined that this tick-borne disease is endemic to the San Gabriel Mountains near the greater Los Angeles metropolitan area.

Show MeSH
Related in: MedlinePlus