Share your insights

Help us by sharing what content you've recieved in your exams


Lyme disease

Background knowledge ๐Ÿง 

Definition

  • Lyme disease is an infectious disease caused by the Borrelia burgdorferi bacteria.
  • Transmitted to humans through the bite of infected black-legged ticks.
  • Common in areas with high tick populations, particularly in wooded and grassy areas.

Epidemiology

  • Incidence varies by region; more common in the Northern Hemisphere.
  • In the UK, most cases are reported in southern England and Scotland.
  • Risk highest during late spring to early autumn when ticks are most active.
  • Outdoor activities in endemic areas increase exposure risk.
  • Reported cases have been increasing due to better awareness and reporting.

Pathophysiology

  • Bacteria enter the skin through the tick bite and spread through the bloodstream.
  • Elicits an immune response leading to characteristic symptoms.
  • Can affect multiple systems including the skin, joints, heart, and nervous system.
  • Chronic inflammation can occur if untreated, leading to long-term complications.
  • Borrelia can evade the immune system, making eradication challenging.

Aetiology/Causes/Risk factors

  • Caused by Borrelia burgdorferi, a spirochete bacterium.
  • Transmitted via bites from infected Ixodes ticks (e.g., Ixodes ricinus).
  • Risk factors include spending time in wooded or grassy areas, lack of protective clothing, and not using tick repellents.
  • Pets can carry ticks into homes, increasing risk.
  • Higher risk in endemic areas and during tick season.

Types

  • Early localized Lyme disease: Erythema migrans at the site of the tick bite.
  • Early disseminated Lyme disease: Multiple erythema migrans lesions, neurologic and cardiac involvement.
  • Late disseminated Lyme disease: Arthritis, chronic neurological symptoms.
  • Post-treatment Lyme disease syndrome: Persistent symptoms after treatment, often controversial.

Clinical Features ๐ŸŒก๏ธ

Symptoms

  • Early signs include erythema migrans (bullseye rash), fatigue, fever, chills, headache, and muscle/joint aches.
  • Neurological symptoms such as facial palsy, meningitis, and radiculopathy.
  • Cardiac symptoms like myocarditis, heart block, and palpitations.
  • Late symptoms include arthritis, particularly in large joints like the knee.
  • Chronic symptoms may include cognitive impairment, fatigue, and neuropathy.
  • Non-specific symptoms such as malaise and generalized pain.
  • Symptoms can vary greatly in severity and presentation.

Signs

  • Erythema migrans: Characteristic expanding rash with central clearing.
  • Facial nerve palsy (Bell’s palsy).
  • Signs of meningitis: neck stiffness, photophobia.
  • Arthritis with joint swelling and pain, typically monoarticular.
  • Heart block or other cardiac conduction abnormalities.
  • Neurological deficits depending on the nerves affected.
  • Lymphadenopathy in some cases.

Investigations ๐Ÿงช

Initial tests

  • Clinical diagnosis based on history of tick exposure and characteristic rash.
  • Serological testing for Borrelia antibodies (ELISA) as first-line test.
  • Confirmatory Western blot test if ELISA is positive or equivocal.
  • Full blood count and inflammatory markers (CRP, ESR) may be elevated.
  • Consider lumbar puncture if neurological symptoms are present.
  • ECG for patients with cardiac symptoms to detect conduction abnormalities.
  • Joint aspiration and synovial fluid analysis if arthritis is present.

Diagnostic tests

  • Two-tiered serological testing: initial ELISA followed by Western blot.
  • PCR testing of blood, CSF, or synovial fluid for Borrelia DNA in specific cases.
  • Skin biopsy of erythema migrans for histopathology and PCR in uncertain cases.
  • Neuroimaging (MRI) if neurological involvement is suspected.
  • Echocardiogram if cardiac involvement is suspected.
  • Consider alternative diagnoses if serology is negative but clinical suspicion remains high.
  • Repeat serology may be necessary in early disease due to delay in antibody production.

Management ๐Ÿฅผ

Management

  • Early localized disease: oral antibiotics (doxycycline, amoxicillin, or cefuroxime) for 14-21 days.
  • Early disseminated and late disease: prolonged courses of antibiotics, consider intravenous therapy (ceftriaxone) for severe cases.
  • Symptomatic treatment for pain and inflammation (NSAIDs, analgesics).
  • Management of complications such as arthritis and cardiac involvement.
  • Regular follow-up to monitor for recurrence or persistent symptoms.
  • Patient education on tick bite prevention and early recognition of symptoms.
  • Consider referral to a specialist for complex or refractory cases.

Complications

  • Chronic arthritis, particularly in large joints.
  • Chronic neurological symptoms (e.g., neuropathy, encephalopathy).
  • Cardiac complications such as heart block or myocarditis.
  • Post-treatment Lyme disease syndrome (persistent symptoms despite treatment).
  • Psychological impact, including anxiety and depression.
  • Secondary infections due to immunosuppressive treatment.
  • Possible autoimmune sequelae triggered by infection.

Prognosis

  • Good prognosis with early diagnosis and appropriate treatment.
  • Delayed treatment can lead to chronic symptoms and complications.
  • Most patients recover fully with standard antibiotic therapy.
  • Persistent symptoms may require long-term management and specialist care.
  • Regular follow-up is essential to monitor for relapse or complications.
  • Education on prevention can significantly reduce the risk of infection.
  • Awareness of symptoms leads to earlier treatment and better outcomes.

Key points

  • Lyme disease is a tick-borne illness caused by Borrelia burgdorferi.
  • Early recognition and treatment are crucial to prevent chronic complications.
  • Characteristic erythema migrans rash aids in early diagnosis.
  • Serological tests (ELISA and Western blot) are standard for diagnosis.
  • Antibiotics are the mainstay of treatment, with choice and duration depending on disease stage.
  • Education on prevention and tick bite awareness is essential.
  • Refer to latest UK guidelines for updated management protocols.

For more detailed guidelines, refer to the latest UK guidelines such as those from NICE:

NICE Guidelines on Lyme Disease

No comments yet ๐Ÿ˜‰

Leave a Reply