Derm

Tick Bite

search

Tick Bite, Tick-Borne Disease, Tick Borne Illness, Alpha-gal Reaction

  • Types
  1. Hard Ticks (Ixodidae)
    1. Hard body casing
    2. Head visible when viewed from above
    3. Responsible for most Tick-Borne Disease (due to ability to adhere to skin for days)
    4. Habitat: Tall grass and brush
  2. Soft Ticks (Argasidae)
    1. Soft, leathery body casing
    2. Head not visible when viewed from above
    3. Habitat: Animal nests
  • History
  • Presentations suggestive of tick-borne illness
  1. Late spring through early fall presentation
  2. Flu-like symptoms
  3. Fever without obvious source
  4. Focal neurologic deficit
  5. Exotic travel or outdoor activities
  6. Pet or livestock exposure
  7. New severe, sudden, Allergic Reaction (Urticaria, Anaphylaxis) to red meat (Alpha-gal Reaction)
    1. Sensitization to galactose-alpha-1,3-galactose (alpha-gal)
    2. Alpha-gal is present in both ticks and red meat (lamb, pork, beef)
    3. Commins (2011) J Allergy Clin Immunol 127(5): 1286-93 [PubMed]
  • Findings
  1. Rash
    1. Lyme Disease (Erythema Migrans)
      1. Develops days 3-21 after Tick Bite
      2. Target or erythematous Plaque >5 cm centered at bite site and gradually increasing to >10-20 cm
    2. Rocky Mountain Spotted Fever
      1. Erythematous Macules (day 6) that transition to Petechiae
      2. Starts on distal extremities (wrists, Forearms, ankles)
    3. Alpha-gal Reaction
      1. Urticarial (or Anaphylaxis) in response to red meat
    4. Ehrlichiosis
      1. Rash occurs in one third of patients (esp. children)
    5. Tularemia
      1. Scab at bite and painful regional adenopathy
  2. Arthritis or Arthralgias
    1. Lyme Disease
      1. Monoarthritis (esp. knee, hip) as early presentation; late presentation with Polyarthritis
  3. Neurologic changes
    1. Lyme Disease
      1. Cranial Nerve dysfunction (esp. Bells Palsy), Meningitis, Sudden Hearing Loss, polyradiculoneuritis
    2. Tick Paralysis
      1. Ascending paralysis starting with leg weakness, areflexia, then upper extremity and head weakness
  4. Cardiac changes
    1. Lyme Disease
      1. Pericarditis, Myocarditis or AV Nodal block
  5. Viral-like syndrome (fever, Headache, malaise, Nausea, Vomiting, cough)
    1. Anaplasmosis
    2. Ehrlichiosis
    3. Rocky Mountain Spotted Fever
    4. Colorado Tick Fever (high, biphasic fever)
    5. Tickborne Relapsing Fever (high fever, Relapsing Fever)
  6. Malaria-like presentation
    1. Babesiosis
      1. Fever, chills, myalgias, Headache, Dark Urine, Anorexia
      2. Possible Hepatosplenomegaly and Jaundice
  • Labs
  • Diagnostic
  1. Does not direct initial management
    1. Most tests are delayed and may be initially normal
  2. Lyme Titer
    1. ELISA with confirmatory western blot
  3. Specific serologic tests (initial and repeated at 2-4 weeks)
    1. Anaplasmosis
    2. Ehrlichiosis
    3. Rocky Mountain Spotted Fever
    4. Tularemia
    5. Colorado Tick Fever
  4. Polymerase Chain Reaction (PCR)
    1. Babesiosis
    2. Tularemia
    3. Colorado Tick Fever
  5. Skin biopsy
    1. Rocky Mountain Spotted Fever (immunohistochemical staining)
  6. Peripheral Smear
    1. Anaplasmosis
      1. Neutrophils with intracytoplasmic inclusions (morulae)
    2. Babesiosis
      1. Maltese cross formation of RBC inclusions (appears similar to Malaria)
    3. Tickborne Relapsing Fever
      1. Spirochetes under dark field microscopy and specific stains
  7. Culture
    1. Tularemia
      1. Culture is gold standard, but is a risk to lab staff (PCR or serology is performed in most cases)
  8. No tests available
    1. Tick Paralysis
  • Diagnostics
  1. Electrocardiogram
    1. AV Nodal Block or Pericarditis (secondary or tertiary Lyme Disease)
  2. Arthrocentesis of Monoarthritis
    1. Increased Synovial Fluid WBCs (may be indistinguishable from Septic Joint)
  • Precautions
  1. Lack of known bite or lack of secondary bite reaction do not exclude Tick Borne Illness
    1. Patients often do not remember an initial Tick Bite
  2. Prompt Tick Removal prevents pathogen transmission (e.g. Lyme Disease) and resolves Tick Paralysis
  3. Start empiric antibiotics immediately if Tick Borne Illness is suspected
    1. Untreated Rocky Mountain Spotted Feveray be lethal by day 8 after Tick Bite
    2. Untreated Lyme Disease may progress to AV Block, Pericarditis, Myocarditis, Polyarthritis, Meningitis, Bells Palsy
    3. Untreated Babesiosis may progress to DIC, Renal Failure and death
  4. Admit patients with significant complications of tick-borne illness
    1. Lyme Disease with Cardiac involvement (e.g. AV nodal block, Pericarditis, Myocarditis)
    2. Lyme Disease with CNS involvement (e.g. Meningitis)
    3. Rocky Mountain Spotted Fever (unless diagnosed early, before day 5 and before rash appears)
    4. Immunocompromised patients or significant complication of other tick-borne illness (Anaplasmosis, Ehrlichiosis)
    5. Babesiosis beyond early phase
  • Causes
  • Ticks
  1. American Dog Tick (Dermacentor variabilis)
    1. Q Fever
    2. Rocky Mountain Spotted Fever
    3. Tick Paralysis
    4. Tularemia
  2. Black-Legged Tick or Deer Tick (Ixodes Scapularis)
    1. Babesiosis
    2. Human Granulocytic Anaplasmosis (Human Granulocytic Ehrlichiosis)
    3. Lyme Disease
    4. Borrelia Miyamotoi (emerging)
      1. Causes Relapsing Fever in endemic Lyme Disease regions
      2. Treated with same antibiotics as Lyme Disease
  3. Western Black Legged Tick (Ixodes pacificus)
    1. Same conditions as for Black-Legged Tick or Deer Tick above
  4. Brown Dog Tick (Rhipicephalus snguineus)
    1. Q Fever
    2. Rocky Mountain Spotted Fever
  5. Lone Star Tick (Amblyomma americanum, white spot on back)
    1. Alpha-gal Sensitivity (IgE Antibody to galactose-alpha 1,3-galactose)
      1. Anaphylaxis to red meat (beef, pork, lamb) as well as cetuximab (Erbitux)
    2. Human Monocytic Ehrlichiosis
    3. Q Fever
    4. Tularemia
    5. Southern Tick-Associated Rash Illness (Masters Disease)
      1. Rash similar to Erythema Migrans (Lyme Disease)
      2. Treated with Doxycycline
  6. Pacific Coast Tick (Dermacentor occidentalis)
    1. Rickettsia phillipi (364D Rickettsiosis)
    2. Rocky Mountain Spotted Fever
    3. Tularemia
  7. Rocky Mountain Wood Tick (Dermacentor andersoni)
    1. Colorado Tick Fever
    2. Q Fever (unproven association)
    3. Powassan Encephalitis (unproven association)
    4. Rocky Mountain Spotted Fever
    5. Tick Paralysis
    6. Tularemia
  8. Soft Ticks (Ornithodoros)
    1. Local pain, inflammation and in some cases necrosis
    2. Relapsing Fever (Borrelia species)
  9. Woodchuck Tick (Ixodes cookei)
    1. Powassan Encephalitis
      1. Rare Encephalitis cause in Northeastern and North Central States
      2. Cognitive Impairment in >50% of survivors, and 10-15% mortality
      3. Unknown treatment
  • Associated Conditions
  • Tick-Borne Conditions by U.S. Frequency
  1. Lyme Disease
    1. Incidence: 30,000 cases per year in U.S.
    2. Distribution: Primarily northeast U.S. and upper midwest (MN, WI)
  2. Rocky Mountain Spotted Fever
    1. Incidence: 6,000 cases per year in U.S.
    2. Distribution: Primarily southeastern United States
  3. Anaplasmosis
    1. Incidence: 5000 cases per year in U.S.
    2. Distribution: Primarily northeast U.S. and upper midwest (MN, WI)
  4. Ehrlichiosis
    1. Incidence: 1500 cases per year in U.S.
    2. Distribution: Primarily southeastern U.S.
  5. Babesiosis
    1. Incidence: 1000-2000 cases per year in U.S.
    2. Distribution: Primarily northeast U.S. and upper midwest (MN, WI)
  6. Tularemia
    1. Incidence: Hundreds of cases per year in U.S.
    2. Distribution: Primarily southcentral U.S.
  7. Colorado Tick Fever
    1. Incidence: 200-300 cases per year in U.S.
    2. Distribution: Rocky Mountains
  8. Tickborne Relapsing Fever
    1. Incidence: 20-30 cases per year in U.S.
    2. Distribution: Rocky Mountains
  • Management
  • Antibiotic Selection
  1. Doxycycline
    1. Avoided in age <8 years unless no alternative (due to dental effects)
    2. Lyme Disease
      1. Indicated in adults, children >8 years old, Penicillin allergic children at any age
    3. Rocky Mountain Spotted Fever
      1. Adults and children regardless of age (despite dental adverse effects)
      2. Do not delay treatment
    4. Anaplasmosis
      1. Adults and children regardless of age (despite dental adverse effects)
    5. Ehrlichiosis
      1. Adults and children regardless of age (despite dental adverse effects)
    6. Tickborne Relapsing Fever
      1. Adults
  2. Atovaquone with Azithromycin
    1. Babesiosis
  3. Clindamycin with Quinine
    1. Babesiosis
      1. Alternative regimen
  4. Amoxicillin
    1. Lyme Disease
      1. Indicated in children <8 years old and those allergic to docycycline
  5. Cefuroxime
    1. Lyme Disease
      1. Indicated in children <8 years old with Penicillin Allergy or those allergic to docycycline
  6. Erythromycin
    1. Tickborne Relapsing Fever
      1. Pregnant women and children <8 years old
    2. Lyme Disease
      1. Other agents are preferred due to lower Macrolide efficacy (use only if allergy to other agents)
  7. Azithromycin
    1. Lyme Disease
      1. Other agents are preferred due to lower Macrolide efficacy (use only if allergy to other agents)
    2. Babesiosis
      1. Treat with combination of Azithromycin AND Atovaquone
  8. Ceftriaxone
    1. Lyme Disease
      1. Seconday or tertiary Lyme Disease
    2. Tickborne Relapsing Fever
      1. Central Nervous System involvement
  9. Chloramphenicol
    1. Rocky Mountain Spotted Fever
      1. Indicated if Doxycycline is contraindicated
    2. Anaplasmosis
      1. Indicated if Doxycycline is contraindicated
    3. Ehrlichiosis
      1. Indicated if Doxycycline is contraindicated
  10. Rifampin
    1. Anaplasmosis
      1. Indicated if Doxycycline is contraindicated
    2. Ehrlichiosis
      1. Indicated if Doxycycline is contraindicated
  11. Streptomycin IM
    1. Tularemia
  12. Gentamicin IM
    1. Tularemia
  13. Supportive Care (No Antibiotics)
    1. Colorado Tick Fever
  • Resources
  1. CDC Tickborne Diseases
    1. http://www.cdc.gov/ticks/diseases/