Lyme Disease

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Basics

Lyme disease is caused by the bacterium Borrelia burgdorferi.

Description

  • A multisystem infection caused by Borrelia spirochetes, transmitted primarily by ixodid ticks
    • Ixodes scapularis (deer ticks) in the Northeast and Great Lakes areas
    • Ixodes pacificus in the West (black-legged ticks and Western black-legged ticks)
    • Ixodes ricinus in Europe
    • Ixodes persulcatus in Asia and Russia
  • Early localized Lyme disease includes a characteristic expanding skin rash (erythema migrans [EM]) (80%) and constitutional flulike symptoms (headache, myalgias, fatigue, fever).
  • Early disseminated Lyme
    • Neurologic manifestations 15%: cranial nerve palsy, meningitis, acute radiculopathy, or mononeuropathy
    • Multiple EM lesions
  • Disseminated Lyme disease presents with involvement of ≥1 organ systems; most commonly neurologic, cardiac, and pauciarticular arthritis
    • Lyme carditis: AV block, myopericarditis 1%
    • Post–Lyme disease syndrome includes arthritis (50%) and chronic neurologic syndromes.
    • System(s) affected: hemic/lymphatic/immunologic; musculoskeletal; skin/exocrine; cardiac; neurologic
  • Synonym(s): Lyme arthritis; Lyme borreliosis

Epidemiology

  • Each year, approximately 30,000 cases of Lyme disease are reported to the Centers for Disease Control and Prevention (CDC).
  • Recent estimates suggest that approximately 300,000 people may get Lyme disease each year in the U.S.

Incidence
  • 2018 high-incidence U.S. states: Wisconsin, West Virginia, Virginia, Vermont, Rhode Island, Pennsylvania, New York, New Jersey, New Hampshire, Minnesota, Massachusetts, Maryland, Maine, District of Columbia, Delaware, Connecticut
  • During 2018, a total of 23,558 confirmed cases of Lyme disease were reported to CDC.
Prevalence
  • The number of counties with an incidence of ≥10 confirmed cases per 100,000 persons increased from 324 in 2008 to 454 in 2017.
  • The most reported vector-borne illness in the United States
  • Predominant age: most common in children ages 5–14 years and in adults aged 55–70 years of age

Etiology and Pathophysiology

  • Infection with spirochete B. burgdorferi in the United States, or Borrelia afzelii or Borrelia garinii in Europe, transmitted by the bite of ixodid ticks
  • Approximately 90% of cases are transmitted during the nymph stage of the tick life cycle.
  • Average incubation period 7 to 10 days
  • Most transmissions occur in late May to September when nymphal tick activity is highest.
  • If a tick is infected, the chance of transmission increases with time attached: 12% at 48 hours, 79% at 72 hours, and 94% at 96 hours of attachment.
  • Primary animal reservoir is the white-footed mouse.
  • Spirochetes multiply and spread within dermis, resulting in characteristic (EM) rash. Hematogenous dissemination results in involvement of central nervous system (CNS), cardiovascular, or other organ systems.
  • Star ticks (Amblyomma americanum), the American dog tick (Dermacentor variabilis), the Rocky Mountain wood tick (Dermacentor andersoni), and the brown dog tick (Rhipicephalus sanguineus) are not known to transmit Lyme disease.

Genetics
Human leukocyte antigen: Patients with haplotype DR4 or DR2 may be more susceptible to prolonged arthritis.

Risk Factors

  • Exposure in Lyme endemic area, particularly from April to November
  • Ixodid ticks are common on deer; hunters at increased risk

General Prevention

  • “Tick checks”: Examine skin after outdoor activities. Ticks live in grassy, brushy, or wooded areas, and on animals.
  • Remove ticks as soon as possible (within 36 hours) to limit transmission.
  • Wear clothing covering the ankles in endemic areas.
  • Use insect repellents containing N,N-diethyl-meta-toluamide (DEET).
  • Apply permethrin to clothes, shoes, and tents.
  • Natural products that repel or kill ticks: 2-indecanone, garlic oil, mixed essential oils (rosemary, lemongrass, cedar, peppermint, thyme, and geraniol)
  • Biological agent products that repel or kill ticks: Fungus called Metarhizium brunneum/Metarhizium anisopliae
  • Antibiotic prophylaxis is recommended for the prevention of Lyme disease in endemic areas following an Ixodes tick bite.
  • Prophylactic treatment with 1 dose of 200 mg of doxycycline within 72 hours of a tick that has been attached for at least 36 hours is indicated in endemic areas. Number needed to treat = 50–53. Contraindicated in pregnancy and in children; no prophylactic agent is approved for these groups (1)[A].

Commonly Associated Conditions

  • Coinfection (e.g., babesiosis) increasingly reported
  • Southern tick–associated rash illness may be mistaken for Lyme disease. It is seen in the Southeastern and South Central United States and is associated with the bite of the lone star tick, A. americanum.
  • Comorbid human granulocytic anaplasmosis and/or babesiosis in patients living in endemic regions

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Basics

Lyme disease is caused by the bacterium Borrelia burgdorferi.

Description

  • A multisystem infection caused by Borrelia spirochetes, transmitted primarily by ixodid ticks
    • Ixodes scapularis (deer ticks) in the Northeast and Great Lakes areas
    • Ixodes pacificus in the West (black-legged ticks and Western black-legged ticks)
    • Ixodes ricinus in Europe
    • Ixodes persulcatus in Asia and Russia
  • Early localized Lyme disease includes a characteristic expanding skin rash (erythema migrans [EM]) (80%) and constitutional flulike symptoms (headache, myalgias, fatigue, fever).
  • Early disseminated Lyme
    • Neurologic manifestations 15%: cranial nerve palsy, meningitis, acute radiculopathy, or mononeuropathy
    • Multiple EM lesions
  • Disseminated Lyme disease presents with involvement of ≥1 organ systems; most commonly neurologic, cardiac, and pauciarticular arthritis
    • Lyme carditis: AV block, myopericarditis 1%
    • Post–Lyme disease syndrome includes arthritis (50%) and chronic neurologic syndromes.
    • System(s) affected: hemic/lymphatic/immunologic; musculoskeletal; skin/exocrine; cardiac; neurologic
  • Synonym(s): Lyme arthritis; Lyme borreliosis

Epidemiology

  • Each year, approximately 30,000 cases of Lyme disease are reported to the Centers for Disease Control and Prevention (CDC).
  • Recent estimates suggest that approximately 300,000 people may get Lyme disease each year in the U.S.

Incidence
  • 2018 high-incidence U.S. states: Wisconsin, West Virginia, Virginia, Vermont, Rhode Island, Pennsylvania, New York, New Jersey, New Hampshire, Minnesota, Massachusetts, Maryland, Maine, District of Columbia, Delaware, Connecticut
  • During 2018, a total of 23,558 confirmed cases of Lyme disease were reported to CDC.
Prevalence
  • The number of counties with an incidence of ≥10 confirmed cases per 100,000 persons increased from 324 in 2008 to 454 in 2017.
  • The most reported vector-borne illness in the United States
  • Predominant age: most common in children ages 5–14 years and in adults aged 55–70 years of age

Etiology and Pathophysiology

  • Infection with spirochete B. burgdorferi in the United States, or Borrelia afzelii or Borrelia garinii in Europe, transmitted by the bite of ixodid ticks
  • Approximately 90% of cases are transmitted during the nymph stage of the tick life cycle.
  • Average incubation period 7 to 10 days
  • Most transmissions occur in late May to September when nymphal tick activity is highest.
  • If a tick is infected, the chance of transmission increases with time attached: 12% at 48 hours, 79% at 72 hours, and 94% at 96 hours of attachment.
  • Primary animal reservoir is the white-footed mouse.
  • Spirochetes multiply and spread within dermis, resulting in characteristic (EM) rash. Hematogenous dissemination results in involvement of central nervous system (CNS), cardiovascular, or other organ systems.
  • Star ticks (Amblyomma americanum), the American dog tick (Dermacentor variabilis), the Rocky Mountain wood tick (Dermacentor andersoni), and the brown dog tick (Rhipicephalus sanguineus) are not known to transmit Lyme disease.

Genetics
Human leukocyte antigen: Patients with haplotype DR4 or DR2 may be more susceptible to prolonged arthritis.

Risk Factors

  • Exposure in Lyme endemic area, particularly from April to November
  • Ixodid ticks are common on deer; hunters at increased risk

General Prevention

  • “Tick checks”: Examine skin after outdoor activities. Ticks live in grassy, brushy, or wooded areas, and on animals.
  • Remove ticks as soon as possible (within 36 hours) to limit transmission.
  • Wear clothing covering the ankles in endemic areas.
  • Use insect repellents containing N,N-diethyl-meta-toluamide (DEET).
  • Apply permethrin to clothes, shoes, and tents.
  • Natural products that repel or kill ticks: 2-indecanone, garlic oil, mixed essential oils (rosemary, lemongrass, cedar, peppermint, thyme, and geraniol)
  • Biological agent products that repel or kill ticks: Fungus called Metarhizium brunneum/Metarhizium anisopliae
  • Antibiotic prophylaxis is recommended for the prevention of Lyme disease in endemic areas following an Ixodes tick bite.
  • Prophylactic treatment with 1 dose of 200 mg of doxycycline within 72 hours of a tick that has been attached for at least 36 hours is indicated in endemic areas. Number needed to treat = 50–53. Contraindicated in pregnancy and in children; no prophylactic agent is approved for these groups (1)[A].

Commonly Associated Conditions

  • Coinfection (e.g., babesiosis) increasingly reported
  • Southern tick–associated rash illness may be mistaken for Lyme disease. It is seen in the Southeastern and South Central United States and is associated with the bite of the lone star tick, A. americanum.
  • Comorbid human granulocytic anaplasmosis and/or babesiosis in patients living in endemic regions

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