Borrelia and Lyme Disease Notes

Borrelia Overview

  • Highly motile spirochete bacteria that are microaerophilic.
  • Transmission occurs through arthropods such as ticks and lice.
    • Transmitted to insects by feeding on infected animals, then transferred to humans upon biting.
  • B. burgdorferi is the causative agent of Lyme Disease, the most common species found in the U.S.
  • Other Borrelia species cause relapsing fever, a febrile illness that recurs as the organism changes antigens to evade the immune response.

Relapsing Fever

  • Caused by various Borrelia species, including B. hermsii and B. turicatae.
  • Characterized by:
    • Sudden onset of fever.
    • Lasts about one week, followed by relapse periods as the bacteria change antigens.
    • May cause a rash similar to that of Lyme Disease.
  • Can be transmitted via lice or ticks and is found globally.

Lyme Disease

Causative Agent: Borrelia burgdorferi
  • An endemic inflammatory disorder primarily occurring in summer months.
  • Symptoms:
    • Initial distinctive bull’s-eye rash (erythema migrans) appears 7-14 days post tick bite.
    • Approximately 70% of patients develop this rash.
    • Following the rash:
    • Flu-like symptoms: headache, muscle aches, joint pain.
    • If untreated, may develop into chronic arthritis, nervous system issues (including facial paralysis), or cardiac problems.
Lifecycle of the Ixodes scapularis Tick
  • Life cycle spans two years, requiring three blood meals:
    1. Year 1:
    • Eggs hatch into uninfected six-legged larvae.
    • Larva feeds on small animals, may become infected.
    1. Year 2:
    • Larva transforms into eight-legged nymph.
    • Nymph feeds on deer/humans, potentially transmitting infection after 48 hours of attachment.

History of Lyme Disease

  • 1975: Outbreak noticed by a mother in Lyme, CT; led to investigations confirming higher incidence of juvenile arthritis.
  • Clusters identified: New England, Wisconsin, Minnesota, California, and Oregon
  • Highest incidence in Connecticut.
  • DNA of B. burgdorferi found in a tick collection over 100 years old, suggesting the long-term presence of the bacteria.

Lyme Disease Vector in Connecticut

  • The only tick known to carry Lyme disease in Connecticut is the deer tick (Ixodes scapularis).
  • Field mouse acts as the primary reservoir for the bacterium; deer ticks do not harbor the bacteria themselves.
  • Ticks are small (size of a poppy seed) and require 48 hours of attachment to transmit the bacteria to humans.

Diagnosis of Lyme Disease

  • Classic sign is the bull's-eye rash (erythema migrans).
  • Methods:
    • Skin biopsy to identify spirochetes under a microscope.
    • Serology is the most common diagnostic method:
    • Increase in antibodies titer (IgM).
    • ELISA (Enzyme-Linked Immunosorbent Assay) is widely utilized for testing.

Treatment of Lyme Disease

  • Common antibiotics:
    • Doxycycline
    • Tetracycline
    • Amoxicillin
    • Erythromycin
  • In advanced cases with arthritis or cardiac issues, IV antibiotics may be essential.
  • Some neurological and cardiac complications may be irreversible, and treatment duration can extend to months.
Lyme Vaccine
  • A Lyme disease vaccine is no longer available, as production was discontinued in 2002 due to diminished protection over time and complications arising from its use.

Prevention Strategies

  • Use DEET-containing repellent on skin.
  • Wear long sleeves and tuck pant legs into boots or socks to minimize skin exposure.
  • Inspect for any new moles or ticks after outdoor activities.
  • Remove ticks promptly with tweezers or forceps and consider sending them to health authorities for testing.