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Emergency and Acute Medicine – Lyme Disease
Basics description
Lyme disease is the most common tick-borne illness in North America. It is endemic in the northeastern United States, the upper Midwest, and parts of northwestern California. The disease follows a multisystem course and may present with dermatologic, neurologic, cardiac, and musculoskeletal manifestations.
Etiology and pathophysiology
Lyme disease is caused by the spirochete Borrelia burgdorferi, which is transmitted through the bite of an Ixodes tick, most commonly Ixodes dammini (the deer tick). Transmission occurs primarily between April and November, with 80–90% of cases in the summer months. Fewer than half of patients recall a tick bite. Disease pathogenesis involves organism-induced local inflammation, cytokine release, and autoimmune mechanisms. There is no person-to-person transmission. A related spirochete, Borrelia miyamotoi, has also been identified as a cause of a Lyme-like illness.
Clinical presentation and stages
Lyme disease progresses through three clinical stages, although not all patients experience every stage.
Stage I, or early localized disease, begins days to weeks after a tick bite. The hallmark finding is erythema chronicum migrans, a pathognomonic expanding annular rash greater than 5 cm in diameter, often with central clearing and a red outer border (“bull’s-eye” rash). Associated symptoms include regional lymphadenopathy, low-grade fever, headache, myalgias, arthralgias, fatigue, and malaise.
Stage II, or early disseminated disease, occurs days to weeks after infection and is characterized by intermittent, fluctuating symptoms. Neurologic involvement includes the triad of aseptic meningitis, cranial neuritis, and radiculoneuritis, with facial (Bell) palsy being the most common cranial nerve deficit. Cardiac manifestations may include tachycardia, bradycardia, atrioventricular block, and myopericarditis. Rash may be absent at this stage. Prognosis is generally good with appropriate treatment.
Stage III, or late disease, develops months to years after initial infection. Musculoskeletal involvement is most common, typically presenting as recurrent monoarticular or oligoarticular arthritis, most often affecting the knee. Dermatologic findings may include acrodermatitis chronica atrophicans on the extensor surfaces of the extremities. Less commonly, late neurologic complications such as chronic polyneuropathy or encephalopathy may occur. A Jarisch–Herxheimer reaction, consisting of transient symptom worsening shortly after treatment initiation, may be seen.
Special populations
Children are more likely than adults to present with fever and may lack a history of erythema migrans. Facial palsy in pediatric patients is frequently associated with aseptic meningitis. Cardiac involvement may be asymptomatic but detectable on ECG. With appropriate treatment, children generally have excellent long-term outcomes. There is no clear evidence that Lyme disease during pregnancy causes fetal harm.
Diagnosis and evaluation
Lyme disease is primarily a clinical diagnosis. The presence of erythema migrans eliminates the need for serologic testing. In patients without the classic rash, serologic testing with ELISA followed by confirmatory Western blot is indicated. Lumbar puncture is reserved for patients with meningeal signs, arthrocentesis for acute arthritis, and ECG for suspected cardiac involvement.
Laboratory findings are nonspecific and may include elevated erythrocyte sedimentation rate, mild cytopenias, or elevated liver enzymes. Cerebrospinal fluid analysis may show pleocytosis and elevated protein in neuroborreliosis.
Differential diagnosis
The differential diagnosis includes other tick-borne illnesses, viral meningitis, septic arthritis, rheumatic fever, syphilis, parvovirus B19 infection, infectious endocarditis, juvenile idiopathic arthritis, fibromyalgia, and chronic fatigue syndrome.
Treatment
Initial stabilization focuses on hydration, IV access for neurologic or cardiac involvement, and cardiac monitoring when indicated. Tick removal should be performed promptly using blunt forceps applied close to the skin.
Antibiotic therapy depends on disease stage and severity. Early localized disease is treated with oral antibiotics such as amoxicillin, doxycycline (for patients ≥8 years old and nonpregnant), or cefuroxime. Disseminated disease with mild neurologic involvement may be treated orally, while meningitis, significant carditis, or severe arthritis requires parenteral therapy, typically with ceftriaxone, cefotaxime, or penicillin G. Late disease usually requires prolonged parenteral therapy. NSAIDs are used for arthralgias and arthritis, and aspirin may be used adjunctively in cardiac involvement.
Disposition and follow-up
Hospital admission is required for patients with meningoencephalitis or significant cardiac involvement requiring telemetry or ICU monitoring. Patients with uncomplicated disease treated with oral antibiotics may be discharged with close outpatient follow-up.
Key points
Early recognition and treatment of Lyme disease prevent late complications. The presence of erythema migrans is diagnostic and should prompt immediate treatment without waiting for serology. Clinicians should remain vigilant for coinfections such as anaplasmosis and babesiosis in endemic regions, and prolonged treatment is required for later-stage organ involvement.
Basics description
Lyme disease is the most common tick-borne illness in North America. It is endemic in the northeastern United States, the upper Midwest, and parts of northwestern California. The disease follows a multisystem course and may present with dermatologic, neurologic, cardiac, and musculoskeletal manifestations.
Etiology and pathophysiology
Lyme disease is caused by the spirochete Borrelia burgdorferi, which is transmitted through the bite of an Ixodes tick, most commonly Ixodes dammini (the deer tick). Transmission occurs primarily between April and November, with 80–90% of cases in the summer months. Fewer than half of patients recall a tick bite. Disease pathogenesis involves organism-induced local inflammation, cytokine release, and autoimmune mechanisms. There is no person-to-person transmission. A related spirochete, Borrelia miyamotoi, has also been identified as a cause of a Lyme-like illness.
Clinical presentation and stages
Lyme disease progresses through three clinical stages, although not all patients experience every stage.
Stage I, or early localized disease, begins days to weeks after a tick bite. The hallmark finding is erythema chronicum migrans, a pathognomonic expanding annular rash greater than 5 cm in diameter, often with central clearing and a red outer border (“bull’s-eye” rash). Associated symptoms include regional lymphadenopathy, low-grade fever, headache, myalgias, arthralgias, fatigue, and malaise.
Stage II, or early disseminated disease, occurs days to weeks after infection and is characterized by intermittent, fluctuating symptoms. Neurologic involvement includes the triad of aseptic meningitis, cranial neuritis, and radiculoneuritis, with facial (Bell) palsy being the most common cranial nerve deficit. Cardiac manifestations may include tachycardia, bradycardia, atrioventricular block, and myopericarditis. Rash may be absent at this stage. Prognosis is generally good with appropriate treatment.
Stage III, or late disease, develops months to years after initial infection. Musculoskeletal involvement is most common, typically presenting as recurrent monoarticular or oligoarticular arthritis, most often affecting the knee. Dermatologic findings may include acrodermatitis chronica atrophicans on the extensor surfaces of the extremities. Less commonly, late neurologic complications such as chronic polyneuropathy or encephalopathy may occur. A Jarisch–Herxheimer reaction, consisting of transient symptom worsening shortly after treatment initiation, may be seen.
Special populations
Children are more likely than adults to present with fever and may lack a history of erythema migrans. Facial palsy in pediatric patients is frequently associated with aseptic meningitis. Cardiac involvement may be asymptomatic but detectable on ECG. With appropriate treatment, children generally have excellent long-term outcomes. There is no clear evidence that Lyme disease during pregnancy causes fetal harm.
Diagnosis and evaluation
Lyme disease is primarily a clinical diagnosis. The presence of erythema migrans eliminates the need for serologic testing. In patients without the classic rash, serologic testing with ELISA followed by confirmatory Western blot is indicated. Lumbar puncture is reserved for patients with meningeal signs, arthrocentesis for acute arthritis, and ECG for suspected cardiac involvement.
Laboratory findings are nonspecific and may include elevated erythrocyte sedimentation rate, mild cytopenias, or elevated liver enzymes. Cerebrospinal fluid analysis may show pleocytosis and elevated protein in neuroborreliosis.
Differential diagnosis
The differential diagnosis includes other tick-borne illnesses, viral meningitis, septic arthritis, rheumatic fever, syphilis, parvovirus B19 infection, infectious endocarditis, juvenile idiopathic arthritis, fibromyalgia, and chronic fatigue syndrome.
Treatment
Initial stabilization focuses on hydration, IV access for neurologic or cardiac involvement, and cardiac monitoring when indicated. Tick removal should be performed promptly using blunt forceps applied close to the skin.
Antibiotic therapy depends on disease stage and severity. Early localized disease is treated with oral antibiotics such as amoxicillin, doxycycline (for patients ≥8 years old and nonpregnant), or cefuroxime. Disseminated disease with mild neurologic involvement may be treated orally, while meningitis, significant carditis, or severe arthritis requires parenteral therapy, typically with ceftriaxone, cefotaxime, or penicillin G. Late disease usually requires prolonged parenteral therapy. NSAIDs are used for arthralgias and arthritis, and aspirin may be used adjunctively in cardiac involvement.
Disposition and follow-up
Hospital admission is required for patients with meningoencephalitis or significant cardiac involvement requiring telemetry or ICU monitoring. Patients with uncomplicated disease treated with oral antibiotics may be discharged with close outpatient follow-up.
Key points
Early recognition and treatment of Lyme disease prevent late complications. The presence of erythema migrans is diagnostic and should prompt immediate treatment without waiting for serology. Clinicians should remain vigilant for coinfections such as anaplasmosis and babesiosis in endemic regions, and prolonged treatment is required for later-stage organ involvement.
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