BSCI 424 — PATHOGENIC MICROBIOLOGY — Fall 2000

Borrelia Summary

Borrelia recurrentis

  Outer sheath encloses axial fibrils wrapped around protoplasmic cylinder

  Axial fibrils originate at both poles and may overlap at center of cell in Treponema and Borrelia, but not in Leptospira

  Relapsing fever (a.k.a., tick fever, borreliosis, famine fever) is an acute infection characterized by a 2-14 day (usually 6 day) incubation period followed by recurring febrile episodes and constant spirochaetemia that worsens during febrile stages

  Tick-borne borreliosis = Endemic Relapsing Fever, sporadic cases, ticks can multiply infect humans

  Louse-borne borreliosis = Epidemic Relapsing Fever, infect host only when louse is injured, e.g., during scratching, therefore, a single louse can only infect a single person, but lice leave host that develops a fever and seek normal temperature host

  Arthropod vectors; Transmitted by soft body ticks or human body lice (vectors) from small mammal reservoir

  Associated with poverty, crowding, and warfare

Borrelia burgdorferi

  Spirochetes with outer sheath enclosing axial fibrils wrapped around protoplasmic cylinder

(see WebLinked image)

  Axial fibrils originate at both poles and may overlap at center of cell in Treponema and Borrelia, but not in Leptospira

  Lyme disease recognized syndrome in 1975; Characterized by three stages:

1. Initially a unique skin lesion (erytema chronicum migrans (ECM)) with general malaise, lesions periodically reoccur
2. Subsequent stage (in 5-15% of patients) have neurological or cardiac involvement
3. Third stage involves migrating episodes of non-destructive, but painful arthritis

  Transmitted by hard body ticks (usually nymph stage are more aggressive vectors) from deer mouse or deer reservoirs

  Acute illness treated with phenoxymethylpenicillin or tetracycline

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