Lyme Disease – Morning Report – July 12 2022

In morning report on July 12 we discussed Lyme disease around a case where a patient presented with migratory polyarthralgias. See a summary of the key points below:


Lyme disease is a tick borne illness, caused by the spirochete BorreliellaBorreliella burgdorferi is the primary cause of the disease in North America. Transmission is most likely to occur via tick bite between the months of May and October with a peak in June. 

Clinical manifestations:

Early localized disease
(days to one month after tick bite)
Early disseminated disease
(weeks to months after tick bite)
Late disease 
(months to years after tick bite)
Erythema migrans (80%)MSK (60% if untreated)
– Migratory polyarthralgias 

Neurologic disease (15% if untreated)
– CN VII palsy
– Lymphocytic meningitis
– Peripheral neuropathy 

Carditis (1%)
– AV nodal block
– mild cardiomyopathy 

– Multiple erythema migrans lesions

– hepatitis

– regional or generalized 
MSK (60% if untreated)
– mono or oligo articular arthritis; knee is most common

– peripheral neuropathy
– encephalomyelitis 

Approach to Diagnosis:

Erythema migrans (single or multiple lesions) – this diagnosis should be made on clinical grounds alone in patients who either live in or have recently travelled to an endemic area. Serologic testing is not needed or recommended prior to treatment.

Early disseminated or late disease – serologic testing is warranted (except in patients with multiple erythema migrans lesions, which are diagnostic in and of themselves). Serum antibodies for B. burgdoferi should be sent. 

note – serologic testing for B. burgdorferi is not particularly sensitive or specific for Lyme, so it should only be used as an adjunct to the clinical diagnosis and should not be used alone to rule Lyme in or out


(if [need all 3]
1.Tick is a deer tick
2.Tick attached >36h
3.Prophylaxis given within 72h tick removal)
Early localized disease
(days to one month after tick bite)
Early disseminated disease
(weeks to months after tick bite)
Late disease (months to years after tick bite)
Doxycycline 200mg PO x 1 doseDoxycycline 100mg PO BID x10 daysNeurologic Disease
(CN VII palsy, meningitis, peripheral neuropathy):
Doxycycline 100mg PO BID x 14-21 days 

Severe Neurologic Disease (encephalitis):
Ceftriaxone 2g IV daily x14-28 days 

Carditis (mild: asymptomatic with 1stdegree AV block and PR<300):
Doxycycline 100mg PO BID x 14-21 days 

Carditis (more severe: symptomatic, 2nd or 3rd degree AV block, PR>300):
Ceftriaxone 2g IV x14-21 days
Doxycycline 100mg PO BID x28 days
(if no improvement, THEN) –
Ceftriaxone 2g IV daily x14-28 days 


1.        Treatment of Lyme disease – UpToDate. disease&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2. Accessed July 14, 2022.

2.        Bailey J. Lyme Disease guidelines. CMAJ. 2016;188(10):754-755. doi:10.1503/CMAJ.1150107

3.        Clinical manifestations of Lyme disease in adults – UpToDate. disease&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1. Accessed July 14, 2022.

4.        Deer Tick | National Geographic. Accessed July 14, 2022.

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