Overview
Definition:
Lyme disease is a tick-borne illness caused by the bacterium Borrelia burgdorferi, transmitted to humans through the bite of infected blacklegged ticks
In children, it can manifest in various stages, broadly categorized into early localized, early disseminated, and late disseminated disease, with arthritis being a prominent manifestation of the latter stages.
Epidemiology:
Lyme disease is the most common vector-borne illness in the United States and parts of Europe
Incidence rates are highest in endemic areas during warmer months when ticks are most active
Children are particularly susceptible due to outdoor activities
Geographic distribution is key, with high-risk regions including the Northeastern and upper Midwestern United States and parts of Europe and Asia.
Clinical Significance:
Prompt recognition and management of Lyme disease in children are crucial to prevent long-term morbidity
Untreated early disseminated disease can lead to serious neurological, cardiac, and musculoskeletal complications
Understanding the nuances between early disseminated manifestations and Lyme arthritis is essential for accurate diagnosis and appropriate treatment, impacting patient outcomes and resident preparedness for examinations.
Early Disseminated Presentation
Symptoms:
Fever
Chills
Headache
Fatigue
Muscle and joint aches
Swollen lymph nodes
Multiple erythema migrans lesions appearing days to weeks after the initial bite
Cranial nerve palsies, particularly facial nerve (Bell's palsy)
Meningitis or meningoencephalitis symptoms
Carditis symptoms, including palpitations, shortness of breath, and dizziness.
Signs:
Widespread erythema migrans rashes, often smaller and more numerous than the primary lesion
Conjunctivitis
Photophobia
Generalized lymphadenopathy
Objective neurological findings such as decreased reflexes or cranial nerve deficits
Tachycardia, irregular heart rhythm, or heart block on physical examination.
Diagnostic Criteria:
Diagnosis is primarily clinical, supported by serology
The presence of at least one objective sign of disseminated disease (e.g., multiple EM lesions, neurological involvement, carditis) in a patient from an endemic area, along with exposure history, strongly suggests early disseminated Lyme disease
Serological tests (ELISA followed by Western blot) are often positive but may be negative in early stages.
Arthritis Presentation
Symptoms:
Recurrent attacks of joint swelling and pain, often affecting large joints like the knees, ankles, and elbows
Episodes may last for weeks or months
Intermittent joint symptoms are characteristic
Children may present with limping or refusal to walk due to joint pain.
Signs:
Swollen, warm, and erythematous joints, typically with effusion
Restricted range of motion in affected joints
Palpable joint effusions
Signs of inflammation within the joint
Absence of systemic symptoms like fever during isolated arthritis episodes.
Diagnostic Criteria:
Lyme arthritis is typically diagnosed in patients with a history of Lyme disease (even if unrecognized), characteristic intermittent arthritis affecting one or a few large joints, and a positive serological test for Borrelia burgdorferi
Exclusion of other causes of arthritis is important, especially in endemic areas
The presence of Borrelia burgdorferi antibodies in synovial fluid can be diagnostic.
Diagnostic Approach
History Taking:
Detailed exposure history to ticks, including recent outdoor activities (hiking, camping) and potential tick bite locations
Onset and progression of symptoms
Travel history to endemic areas
History of previous Lyme disease
Evaluation for constitutional symptoms (fever, fatigue) and specific organ system involvement (neurological, cardiac, musculoskeletal).
Physical Examination:
Thorough skin examination for erythema migrans, noting size, shape, and presence of multiple lesions
Complete neurological examination, assessing cranial nerves, motor strength, sensation, reflexes, and gait
Cardiovascular examination, including heart rate, rhythm, and signs of heart block
Musculoskeletal examination, focusing on joint swelling, tenderness, range of motion, and effusion.
Investigations:
Serological testing for Lyme disease: Enzyme-linked immunosorbent assay (ELISA) for antibodies, followed by a confirmatory Western blot if ELISA is positive or equivocal
IgM and IgG antibodies are tested
In early Lyme, IgM may be positive, while IgG develops later
For Lyme arthritis, synovial fluid analysis may reveal a lymphocytic pleocytosis and elevated protein
Joint aspiration for culture and PCR can be considered but is often negative.
Differential Diagnosis:
For early disseminated disease: viral exanthems, other tick-borne illnesses (e.g., Rocky Mountain spotted fever), infectious mononucleosis
For Lyme arthritis: septic arthritis, reactive arthritis, juvenile idiopathic arthritis, other connective tissue diseases, trauma, osteomyelitis
Careful consideration of symptom patterns and patient demographics is vital.
Management
Medical Management:
Treatment depends on the stage and manifestations
For early disseminated Lyme disease: Doxycycline (for children >8 years old) 2.2 mg/kg per dose PO BID for 14-21 days
Amoxicillin (for children <8 years old) 50 mg/kg per day PO TID for 14-21 days
For Lyme arthritis: Oral antibiotics are usually sufficient, with doxycycline or amoxicillin for 21-28 days
In refractory cases or with neurological/cardiac involvement, intravenous ceftriaxone (2 g IV once daily for 14-28 days) may be necessary
Duration of therapy is tailored to clinical response.
Supportive Care:
Symptomatic management of fever and pain with analgesics and antipyretics
For neurological involvement, anticonvulsants or corticosteroids may be indicated in specific cases
Monitoring for treatment response and potential adverse effects of antibiotics is essential
Patient education on tick prevention is crucial.
Complications
Early Complications:
Facial palsy (Bell's palsy)
Peripheral neuropathy
Aseptic meningitis
Myopericarditis (ranging from mild conduction abnormalities to myocarditis and tamponade)
Ocular manifestations such as conjunctivitis or uveitis.
Late Complications:
Lyme arthritis, particularly affecting the knee
Chronic neurological sequelae, including encephalopathy and radiculoneuropathy
Acrodermatitis chronica atrophicans (more common in Europe)
Post-treatment Lyme disease syndrome (PTLDS), characterized by persistent fatigue, pain, and cognitive symptoms, though its pathogenesis and definition remain debated.
Prevention Strategies:
Tick avoidance measures: using insect repellent containing DEET or picaridin, wearing protective clothing, avoiding tick-infested areas
Prompt removal of ticks: using fine-tipped tweezers to grasp the tick as close to the skin surface as possible and pull upward with steady, even pressure
Thoroughly cleaning the bite area and hands after tick removal
Awareness of Lyme disease symptoms and seeking medical attention if symptoms develop after a potential tick exposure.
Prognosis
Factors Affecting Prognosis:
Timeliness of diagnosis and treatment is the most critical factor
Children who receive prompt antibiotic treatment generally have an excellent prognosis
Delays in diagnosis and treatment can lead to more persistent and severe complications.
Outcomes:
With appropriate antibiotic therapy, most children with early disseminated Lyme disease and Lyme arthritis recover fully
Recurrence of arthritis may occur but is less common with adequate treatment
Long-term neurological or cardiac issues are rare with prompt management but can occur with delayed treatment.
Follow Up:
Follow-up is typically based on clinical response
Patients should be advised to monitor for any new or persistent symptoms
Repeat serological testing is generally not recommended for uncomplicated Lyme disease after adequate treatment
For complex cases or persistent symptoms, further evaluation and specialist consultation may be required.
Key Points
Exam Focus:
Differentiate between early disseminated Lyme and Lyme arthritis based on clinical presentation
Recognize the typical age groups affected by different manifestations
Know the primary treatment regimens and durations for pediatric Lyme disease
Understand the importance of tick exposure history and geographic endemicity.
Clinical Pearls:
The classic erythema migrans rash is not always present in children with disseminated disease
Facial nerve palsy is a common neurological manifestation
Knee is the most frequently affected joint in Lyme arthritis
Always consider Lyme disease in children presenting with unexplained migratory arthralgias or recurrent joint effusions, especially in endemic areas.
Common Mistakes:
Misdiagnosing Lyme arthritis as a traumatic injury or common juvenile arthritis
Prescribing inadequate duration or inappropriate antibiotics
Over-reliance on serology in early stages where it may be negative
Failing to consider Lyme disease in children with unexplained neurological or cardiac symptoms in endemic regions.