Lyme disease in Canada: Focus on children

Question 1

What causes Lyme disease?

Answer 1

Borrelia burgdorferi

Question 2

How is Lyme disease transmitted?

Answer 2

Bite of infected black legged deer tick

Question 3

What are the primary hosts (carriers) for the black-legged tick?

Answer 3

1. Mice
2. Other small rodents
3. Small mammals
4. Birds (reservoirs)
5. White tailed deer

Question 4

What is the peak incidence of Lyme disease?

Answer 4

Children 5-9yo

Adults 55-59yo

Question 5

When must a tick be removed after starting feeding to prevent LD?

Answer 5

Within 24-36h

Question 6

What is the prevalence of LD?

Answer 6

> 500 cases in 2013

Question 7

What is early localized disease?

Answer 7

1. Erythema migrans (7-14d), resolves within 4wk without treatment
2. Fever
3. Malaise
4. Headache
5. Mild neck stiffness
6. Myalgia
7. Arthralgia

Question 8

What is early disseminated disease?

Answer 8

~20% of children present

1. Multiple EM lesions (usu. several weeks post tick bite) = spirochetemia w/ cutaneous dissemination
2. Acute neurological signs i.e. facial nerve palsy, papilledema, lymphocytic meningitis
3. Lyme carditis causing heart block rare

Question 9

What is late disease?

Answer 9

Rare if treated with antimicrobials early in disease
Weeks to months post bite
1. Pauciarticular arthritis affecting large joints esp. knees
2. Peripheral neuropathy
3. CNS manifestations

Question 10

How to diagnosis LD?

Answer 10

1. Early localized disease –> diagnose if history of potential tick exposure and symptoms in an area with LD
   Antibodies are undetectable until 4weeks after infection

Early disseminated disease or late LD: ELISA screening test (may yield false positive test) with confirmatory Western blot test

If travel history to Europe require European IgG Western blot as well.
If arthritis present ~97% positive antibodies, if neurological involvement ~80% positive antibodies, if acute EM ~30-50% positive antibodies, if EM late 75-80% positive for antibodies

Question 11

What is the recommended antibiotic therapy for LD?

Answer 11

1. > 8yo: Doxycycline 4mg/kg/day PO BID
2. <8yo: Amoxicillin 50mg/kg/day PO TID

Alternative: Cefuroxime 30mg/kg/day PO BID

IV: Ceftriaxone 50-75mg/kg IV daily
Pen G 200 000-400 000U/kg/day IV q4h

Question 12

What is the recommended route/duration of antibiotic therapy for LD?

Answer 12

1. Erythema migrans 14-21d PO
2. Isolated facial palsy 14-21d PO
3. Multiple erythema migrans 21d PO
4. Arthritis 28d PO
5. Recurrent or persistent arthritis 28d PO/IV
6. Heart block or carditis 14-21d IV
7. Meningitis 10-28d (14d) IV
8. Encephalitis or late neurological disease 14-28d IV

Question 13

What is the Jarisch-Herxheimer reaction?

Answer 13

Fever, headache, myalgia, and an aggravated clinical picture lasting <24h after initiation of antimicrobials.

Treat with NSAID and continue antimicrobials

Question 14

What is post treatment Lyme disease syndrome?

Answer 14

10-20% of cases experience lingering fatigue, joint and muscle ache >6m
Likely residual damage to tissue and immune system. Do not retreat with antimicrobials

Question 15

How to remove a tick?

Answer 15

1. Use fine-tipped tweezers to grasp the tick close to the skin surface
2. Pull upward with steady, even pressure. Try not to twist or jerk, which can cause the mouthpart of the tick to break off and remain in the skin. If this happens and you are unable to remove the mouthpart easily with clean tweezers, leave it alone and let the skin heal.
3. Clean the bite area and your hands with rubbing alcohol, an iodine scrub, or soap and water

Question 16

What does the Public Health Agency of Canada advise?

Answer 16

1. Keep any ticks they remove themselves in a resealable plastic bag or pill vial and note the location and date of the bite.
2. Watch for symptoms and see a health care professional immediately should symptoms appear.
3. Take the tick with them to their medical appointment, to verify species and test as needed

Question 17

How can LD be prevented?

Answer 17

1. Where play spaces adjoin wooded areas, landscaping can reduce contact with ticks
2. Apply 20% to 30% DEET or icaridin repellents. Repellents can be applied to clothing as well as to exposed skin. Always read and follow label directions
3. Do a ‘full body’ check every day for ticks. Promptly remove ticks found on yourself, children and pets. Shower or bathe within two hours of being outdoors to wash off unattached ticks

Question 18

What is the recommendations on post-exposure antibiotic therapy?

Answer 18

Consider doxycycline 4mg/kg (max 200mg) PO x 1 dose for children >8yo after a tick bite within 72h of removing a tick even if its been attached for >36h
Insufficient evidence for amoxicillin prophylaxis in younger children