Diagnosis

Lyme disease

Etiology

Cause [7k3]

• The bacterial spirochete Borrelia burgdorferi (or other Borrelia species) is transmitted by the bite of an Ixodes genus tick

Pathofysiology [e5b][7k3]

• Once in the skin, the spirochete can evade the host immune response and undergo hematogenous and lymphatic dissemination

• Borrelia burgdorferi shows a distinct tropism for the skin, heart, central nervous system, joints, and eyes

• The spirochete itself is not known to be directly toxic

• The host inflammatory response is responsible for causing tissue damage in organs

1. Early localized: >4 weeks after the bite

   • Asymptomatic but seropositive patient

   • Erythema migrans.

2. Early disseminated: weeks to months after the bite

   • Erythema migrans

   • Lymphocytoma

   • Arthritis

   • Meningitis

   • Facial nerve paralysis

   • Cardiac disturbances/Carditis

3. Chronic disseminated: months to years after infection

   • Arthritis

   • Neuroborreliosis

     • Encephalomyelitis/encephalopathy

     • Chronic progressive encephalomyelitis

     • Late axonal neuropathies

   • Posttreatment Lyme disease syndrome

Complications [7k3]

• Arthritis

• Carditis

• Neurological deficits

• Ocular manifestations

• Acrodermatitis chronica atrophicans

• Lymphocytoma

Epidemiology

Incidence per 100.000 [3ks][gui][isf]

Approach

• Serology (detect exposure, not infection)

• Biopsy

• Culture

• PCR

• Spinal fluid

• ECG

• MR caput

Treatment

Treatment strategy depends on clinical presentation: [7k3]

1. Asymptomatic patients with potential exposure: Ixodes, endemic area, tick was attached for ≥36 hours

   • Doxycycline 200 mg for adults and 4.4 mg/kg (up to a maximum dose of 200 mg) for children

2. Erythema migrans rash in endemic area:

   • 10-day course of doxycycline or a 14-day course of amoxicillin or cefuroxime axetil

3. Neurologic manifestations: Intravenous ceftriaxone, cefotaxime, penicillin G, or oral doxycycline for 14 to 21 days

4. Cardiac manifestations: 

   • heart block --> temporary pacemaker

   • Oral doxycycline

   • Lyme carditis --> IV ceftriaxone for 14 to 21 days

5. Arthritis: 

   • Oral doxycycline for 28 days

   • If minimal or no response --> IV ceftriaxone for 2 to 4 weeks

   • If refractory to antibiotics --> intra-articular corticosteroid injections, use of disease-modifying agents or other advanced therapies should be considered

6. Borrelial lymphocytoma: Oral antibiotic therapy for 14 days

7. Acrodermatitis chronica atrophicans: Oral antibiotic therapy for 21 to 28 days

8. Posttreatment Lyme Disease Syndrome:

   • 10-20% will not respond to treatment and can develop PTLDS (no objective manifestations such as active rash, cardiac or neurologic findings, or arthritis, but with persistent or recurring nonspecific symptoms such as fatigue, pain, or cognitive impairment.

   • Symptomatic management (NSAIDs, acetaminophen, heating pads, and physical therapy)

9. Antibiotic Refractory Lyme Arthritis:

   • 10% experience persistent inflammatory arthritis that does not respond to antibiotic treatments --> referral to a rheumatologist

Differential diagnoses

Acute rheumatic fever, Ankylosing spondylitis, AV nodal block, Babesiosis, Breast cancer, Cellulitis, Cervical radiculopathy, Chronic venous insufficiency, COVID-19, Depression, Dermatomyositis, Drug eruptions, Eczema, Ehrlichiosis, Encephalitis, Erysipelas, Erythema multiforme, Gout, Granuloma annulare, Hypothyroidism, Insect Bite, Lymphoma, Meningitis, Morphea, Multiple sclerosis, Myocarditis, Paget's disease, Parvovirus B19, Pericarditis, Pityriasis rosea, Psoriatic arthritis, Reactive arthritis, Rheumatoid arthritis, Rocky mountain spotted fever, Sarcoidosis, Scleroderma, Septic arthritis, Syphilis, Systemic lupus erythematosus, Thrombophlebitis, Tinea, Urticaria