Lyme Disease

A tick-borne infection (Borrelia burgdorferi, via Ixodes ticks) endemic to the north-eastern/upper-midwestern USA, Europe, and parts of Asia. Not locally acquired in Australia — only ever diagnose it in a returned traveller (patients may not recall the bite). See also Tick bite.

When to suspect it

• Travel to, or residence in, an endemic region in the weeks before symptom onset — always take a travel history.
• An expanding, usually painless “bull’s-eye” rash (erythema migrans) at a bite site.
• Unexplained facial palsy, radiculopathy, meningitis, heart block, or large-joint arthritis in a returned traveller.

Clinical presentation (3 stages)

1. Early localised (days to ~4 weeks post-bite) — erythema migrans, seen in around 70% of patients, with low-grade fever, malaise, headache, and myalgia. Most patients never progress further.
2. Early disseminated (weeks later, ~20% of patients) — multiple erythema migrans lesions, flu-like illness, facial nerve (CN VII) palsy, lymphocytic meningitis or radiculopathy, and cardiac involvement (AV block, myopericarditis).
3. Late (months later) — arthritis, usually pauciarticular and affecting large joints (especially the knee); some patients have no history of a preceding rash.

Testing

Two-step serology (a sensitive screening immunoassay, then a confirmatory test) is unreliable in the first few weeks after infection — a patient with a classic erythema migrans rash and a compatible travel history can be treated clinically without waiting for serology.

Treatment and referral

Doxycycline is first-line for early, localised disease acquired overseas; amoxicillin or cefuroxime is used instead in young children and in pregnancy. Neurological or cardiac involvement needs IV antibiotics — discuss with, or refer to, infectious diseases rather than initiate this in general practice.

The Australian context (important)

Australian Ixodes ticks do not carry Borrelia burgdorferi — a national CSIRO survey confirmed this — so Lyme disease is not locally acquired here, and Australian clinicians can diagnose and treat it in returned travellers as above.

When a patient presents with Lyme-like symptoms without overseas travel:

• Do not diagnose “chronic Lyme disease.” The accepted Australian term for the symptom complex is DSCATT (Debilitating Symptom Complexes Attributed to Ticks) — reported symptoms include fatigue, disordered thinking, sensory disturbance, joint pain, and headache.
• Investigate and treat alternative diagnoses — fibromyalgia, neurological disorders, and psychiatric illness (depression, somatisation) — per the RCPA position statement.
• Investigate for genuine Australian tick-borne diseases instead (e.g. Queensland tick typhus / rickettsioses, Q fever).
• Avoid unvalidated overseas testing and prolonged/repeated antibiotic courses — they don’t improve symptoms and expose patients to harm. Discuss with an expert (infectious diseases or the DSCATT clinical pathway) before requesting testing.

A 2025 Senate Inquiry examined access to diagnosis and treatment for Australians with tick-borne illness; the Australian Government published its response in November 2025.