Lyme Disease

Definition

A tick borne infection by Borrelia burgdorferi sensu lato. Lyme arthritis is the late stage, a mono or oligoarthritis of large joints.

Epidemiology

  • Transmitted by Ixodes ticks in endemic parts of North America, Europe and Asia
  • Highest incidence in the northeastern United States and central Europe
  • Arthritis is more frequent with North American strains

Clinical Features

  • Early localised disease with erythema migrans at the bite site within 30 days
  • Early disseminated disease with carditis, heart block, facial palsy and meningitis
  • Late disease with arthritis months after the bite
  • Knee involved in most cases, with a large tense effusion
  • Effusion often larger and less painful than in septic arthritis
  • Children may present with an irritable hip or knee

Investigations

  • Two tier serology, an ELISA followed by Western blot or a second immunoassay
  • IgG serology is positive in nearly all patients with arthritis
  • Synovial PCR for Borrelia DNA supports the diagnosis
  • Synovial leucocytes usually lower than in septic arthritis
  • Kocher criteria may misclassify Lyme arthritis as septic in endemic areas

Differential Diagnosis

Management

  • Doxycycline. 28 days orally for Lyme arthritis
  • Amoxicillin. 28 days orally in young children or pregnancy
  • Intravenous ceftriaxone. 2 to 4 weeks for persistent arthritis after oral therapy
  • DMARDs or synovectomy. Postinfectious synovitis that persists after antibiotics

Prognosis

  • Most cases resolve with antibiotics
  • Antibiotic refractory arthritis in a minority, linked to HLA-DR4

References

  1. Steere AC, Strle F, Wormser GP, Hu LT, Branda JA, Hovius JW, Li X, Mead PS. Lyme borreliosis. Nat Rev Dis Primers. 2016, 2, 16090. PubMed
  2. Arvikar SL, Steere AC. Diagnosis and treatment of Lyme arthritis. Infect Dis Clin North Am. 2015, 29(2), 269-80. PubMed

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 19 October 2026.