Lyme Disease Flashcards
What is the primary hosts of black legged ticks
Mice and smaller rodents, birds and white tailed deer
Do dogs spread Lyme disease
No. Although they can carry ticks into the home there is no evidence that they spread infection to ppl
What is the age of kids most frequently affected with Lyme disease
5-9 years of age
And older adults 55-59 years
Does Lyme disease in a pregnant mom affect the fetus?
There is no evidence of this.
Which stage of the tick life cycle are most responsible for disease?
Nymphs
Their small size hinders detection
How long do ticks have to feed to cause Lyme disease
Likely longer than 36 hours
If removed within 24-36 hours it is likely not going to cause disease
They can feed for five days!
How common is Lyme disease in Canada
> 500 cases in Canada in 2013
What are the different stages of Lyme disease?
Early localised or disseminated
Late
What are the clinical manifestations of early localised disease and when does it occur relative to the tick bite
Occur within 7-14 days
Erythema migrans at the site of the tick bite. This rapidly expands centrifugally. Sometimes has a central clearing. > 5cm
Systemic symptoms: fever, malaise, headache, mild neck stiffness, myalgia and arthralgia
Without treatment, will early Lyme disease resolve?
Yes!
Without treatment it will resolve within 4 weeks.
What are the clinical manifestations of early disseminated disease and when does it occur?
Occurs several weeks after the tick bite.
Rash: multiple erythema migran lesions. Smaller then primary lesion
Acute neurological signs: facial palsy, (CN VI and VII) papillodema, lymphocytic meningitis.
Lyme carditis is rare (heart block)
What are the clinical manifestations of late disease?
When does it occur?
Pauciarticular arthritis, large joints especially the knee
Manifest weeks to months later
Rarely have peripheral neuropathy or CNS findings.
How is the diagnosis of Lyme disease made?
Early localised: clinically
NB the antibodies can take four weeks to become positive
Early disseminated and late: ELISA ➡️ western blot
Why do you need to do two tierd testing?
ELISA is highly sensitive but poor specificity (yields false positive)
Also positive with autoimmune disease and other viral and spirichete infection.
Western blot is highly specific but poorly sensitive
How do you monitor treatment?
Clinically.
Antibodies are not reliable to follow to monitor for improvement.
What is not used in testing?
Joint aspirate for antibodies and urine antigen.
How do you diagnose CNS meningitis?
LP CSF for IgM and IgG
How do you treat Lyme disease ?
Options: Doxycycline 4mg/kg Amoxicillin 50mg/kg/day Cefuroxime 30mg/kg IV ceftriaxone 50-75 mg/kg IV Penicillin 200090 units/kg/day
How long do you treat for?
Depends in the type. EM 14-21 Isolated facial nerve palsy 14-21 Multiple EM 21 Arthritis 28 Recurrent arthritis 28 Heart block or carditis 14-21 IV Meningitis 14 IV Encephalitis 14-28 days IV
How many ppl have residual symptoms with arthritis
1/3 have residual synovitis and joint swelling
What is jarisch herxheimer reaction?
Fever headache myalgia and an aggravated clinical picture lasting
What is post treatment Lyme disease syndrome and how common is it
Lingering fatigue and joint and muscle aches
10-20%
? Residual damage to tissues and immune system.
Do longer courses of antibiotics prevent PTLDS?
No.
How do you remove a tick?
Tweezers Steady pressure upwards Do to twist or jerk Clean with rubbing alcohol Keep in plastic bag
Can you prevent Lyme disease
Good landscaping if nearby woods
DEET 20-30%
Icarian repellant
Full body check
Should there be post exposure prophylaxis?
Yes. In known endemic areas
Who: tick, within 72 hours of removal, even if attached > 36 hours.
Doxycycline 200 mg x1
Who should not be given doxycycline?
Children
If your patient has worsening symptoms after initiated antimicrobials what does he have and what do you do?
Jarisch-herxheimer reaction
NSAIDs and continue ABx
What causes Lyme disease and how is it transmitted?
Infection with Borrelia burgdorferi transmitted to humans through the bite of an infected black legged tick, Ixodes scapularis and Ixodes pacificus
