questions 6

Lyme Disease

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Topic updated on 06/14/17 2:13pm

Snapshot
  • A 16-year-olPhotod boy presents to his primary care physician with fatigue, headache, and arthralgia. The doctor identifies a ring-shaped lesion on his lower back.
Introduction
  • Lyme Disease is caused by the spirochete Borrelia burgdorferi
  • Transmitted by the Ixodes tick on white-tailed deer and white-footed mice  
    • tick must attach 36-48 hours in order to trasmit B. burgdorferi
  • Most common vector-born disease in the USA
  • Usually observed in the summer months in the Northeast, northern midwest, and California
    • the disease occurs worldwide
  • Disease usually presents in three distinct stages, characterized by symptoms below
Presentation
  • Symptoms
    • prodrome symptoms include
      • fever
      • malaise
      • photophobia
      • erythema chronicum migrans
        • 7-14 days after tick bite
        • spreading circular red rash with central-clearing
    • secondary disease symptoms appear weeks after bite and include
      • weeks-months after tick bite
      • cardiac symptoms
        • myocarditis
        • conduction abnormalities
      • palsies (i.e. Bell's palsy) 
      • aseptic meningitis
      • joint pain (migratory polyarthropathies)
    • tertiary disease symptoms appears weeks to months after bite and include
      • months-years after tick bite
      • arthritis
      • subacute encephalitis
        • memory and mood changes
  • Physical exam
    • prodrome symptoms usually accompanied by identifiable rash
      • identified in areas difficult for patient to see (i.e. lower back, postauricular)
    • all other signs and symptoms identified as described
Evaluation
  • Diagnosis based primarily clinical and laboratory findings 
  • ELISA 
    • if positive, only denotes exposure
    • not specific for active disease
  • Western blot
    • used to confirm positive or indeterminate ELISA
  • Skin biopsy and/or tissue culture
    • of migrating rash may help identify pathogen
  • PCR
    • may aid in identification of Borrelia burgdorferi DNA
Differential
  •  Contact dermatitis, other tick-borne illness (Rocky Mountain Spotted Fever, etc),
Treatment
  • Medical management  
    • doxycycline
      • indicated for treatment of early disease
      • contraindicated in pregnant women and children <8yo
      • side effects include photosensitivity - must caustion patients to avoid sun exposure 
    • amoxicillin: first line treatment for children < 8 yo 
    • high-dose penicillin or ceftriazone
      • indicated for treatment of more advanced disease
      • given for period of 2-4 weeks
    • Macrolides (erythromycin, azithromycin)
      • third line agent if doxycycline contraindicated and allergic to penicillin
    • empiric therapy
      • indicated for patients with characteristic rash, arthralgias, or a tick bite in endemic areas but without confirmed diagnosis
Prognosis, Prevention, and Comlications
  • Prognosis
    • good to excellent if identified early and treated appropriately 
    • poor to fatal if left untreated
  • Prevention
    • take precautions in endemic areas (i.e. wear long clothes, apply DEET insect repellent)
    • examine body for tick bites after potential exposures
  • Complications
    • unidentified/untreated disease can progress to meningitis/encephalitis and death


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Qbank (5 Questions)

TAG
(M2.ID.20) A 6-year-old boy presents to his PCP with the finding shown in Figure A. His father thinks it has been there for about a day. The boy denies other symptoms, although his father remarks that he had a headache last night and seems a bit more fatigued than usual. The family lives in a wooded area, has not traveled at all recently, and has no pets. He has no significant past medical history and no known drug allergies. What is the appropriate treatment? Topic Review Topic
FIGURES: A          

1. Amoxicillin
2. Doxycycline
3. Azithromycin
4. Cephalexin
5. Ceftriaxone

PREFERRED RESPONSE ▶
TAG
(M2.ID.23) A 27-year-old hiker from Massachusetts presented to her primary care physician with a new rash pictured in Figure A. She denied any fevers, chills, arthralgias, or other symptoms. She is prescribed the first-line medication for this condition. The patient then returns 1 week later following another hiking trip with erythema, edema, and vesicles on her face, shoulders, and legs. Which of the following could have prevented this from happening? Topic Review Topic
FIGURES: A          

1. Assessing the patient's allergy history
2. Testing the patient's serum ANA level
3. Cautioning the patient on common side effects of the medication
4. Recommending avoidance of wooded areas
5. This could not have been prevented

PREFERRED RESPONSE ▶
TAG
(M2.ID.51) A 32-year-old patient who is approximately 9 weeks gestation presents to your clinic complaining of a rash on her thigh (see Figure A) that appeared yesterday. She has no other symptoms, and physical exam does not reveal any abnormalities other than the rash. She recently returned from camping in Wisconsin 5 days earlier. Her history is significant only for Lyme disease 2 years earlier, and an episode of streptococcal pharyngitis that was treated with penicillin, to which she had an anaphylactic response. What is the best next course of action? Topic Review Topic
FIGURES: A          

1. Assure her that the rash will resolve on its own
2. Send IgG levels for Borrelia burgdorferi
3. Treat with 10 days of amoxicillin
4. Treat with 10 days of doxycycline
5. Treat with 10 days of erythromycin

PREFERRED RESPONSE ▶
TAG
(M2.ID.71) A 30-year-old avid hiker from Massachusetts presents to your office for a 4 day history of left knee swelling and mild pain. On questioning, she vaguely recalls a rash several months ago, but states it resolved on its own after several weeks. The patient denies fever, chills, recent trauma, changes in vision, and reports only 1 sexual partner in the past 4 years. Vital signs are T 37 C, BP 110/70, P 75, RR 12. On exam, the left knee is warm to the touch and an effusion is present. No target-like lesions on her skin are noted. Besides arthrocentesis and synovial fluid analysis, which of the following is most helpful for diagnosis of this patient? Topic Review Topic

1. Serology testing
2. MRI of left knee
3. Blood culture
4. HLA-B27 testing
5. Gonorrhea and chlamydia testing

PREFERRED RESPONSE ▶
TAG
(M2.ID.73) A 17-year-old female presents to your clinic with a rash on her leg after going hiking in Massachusetts one week ago. She denies fever, chills, or pain. She is otherwise healthy and has no significant medical history. Vital signs are T 37C, HR 80/min, BP 110/70 mmHg, RR 12/min, SpO2 100%. Physical exam reveals a rash on her left leg as seen in the image below (Figure A). Appropriate laboratory studies are performed and confirm the diagnosis. You prescribe her the appropriate medication and instruct her to follow up in one month. Her mother asks you what long-term prognosis is for the patient. Which of the following is the best response? Topic Review Topic
FIGURES: A          

1. Your daughter has a 50% chance of developing additional rashes in one year
2. Your daughter has a 30% chance of developing neurologic symptoms in one year
3. Your daughter has a 40% chance of developing cardiologic symptoms in one year
4. Your daughter will have a 50% lifetime risk of arthritis
5. Your daughter will most likely be disease free

PREFERRED RESPONSE ▶
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