Lyme disease

Lyme disease or Lyme borreliosis (LB) is the most common vector born bacterial infection in the temperate northern hemisphere.

• the infection is caused by the bacterium, Borrelia burgdorferi sensu lato
  • B. afzelii, B. garinii and other related species may also be responsible for Lyme disease in Europe and in Asia
• the infection is spread through the bite of an infected tick of the genus Ixodes
  • the Ixodes ricinus tick is responsible for the transmission of the infection in the UK and Europe while in the USA, Ixodes scapularis (on the west coast Ixodes pacificus predominates) spreads the disease
    • ticks are often found in hard-to-see areas such as the groin, armpits, and scalp (but may attach to any part of the human body)
    • in most cases, the tick must be attached for 36 to 48 hours or more before the Lyme disease bacterium can be transmitted.
  • transmission from person to person or directly from other animals do not occur (1,2,3)

The disease was first recognised in Lyme, Connecticut when a large cluster of children developed arthritis.

Lyme borreliosis is more commonly diagnosed during the summer season, coinciding with tick activity, but cases are reported throughout the year (4).

Public Health England (PHE) reports that there are approximately 1,000 serologically confirmed cases of Lyme disease each year in England and Wales (5)

• many diagnoses will also be made clinically without laboratory testing
• true number of cases is currently unknown. In England and Wales, cases of laboratory-confirmed Lyme disease have increased
• not certain how much of the rise is due to increased awareness and how much to the spread of the disease

A subset of individuals reports persistent symptoms after antibiotic treatment, including fatigue, pain, arthralgia, and neurocognitive symptoms, which in some people are severe enough to fulfil the criteria for post-treatment Lyme disease syndrome (6):

• reported prevalence of such persistent symptoms following antimicrobial treatment varies considerably, and its pathophysiology is unclear
• persistent active infection in humans has not been identified as a cause of this syndrome
• randomized treatment trials have invariably failed to show any benefit of prolonged antibiotic treatment

Key points (7):

• treatment:
  • treat erythema migrans empirically; serology is often negative early in infection
    • serologic antibody testing is of low sensitivity at onset but becomes highly sensitive after a few weeks (8)
• for other suspected Lyme disease such as neuroborreliosis (CN palsy, radiculopathy) seek advice.

The UK Health Security Agency have produced an information resource called the "tick awareness toolkit" (November 6th 2024):

• are approximately 20 species of tick that are endemic in the United Kingdom (UK)
  • of these, the sheep, castor bean or deer tick (Ixodes ricinus) most commonly bites humans and this toolkit focuses on this species
  • ticks can carry a range of microorganisms some of which may cause disease in humans
    • most common of these causes the bacterial infection Lyme disease (LD)
    • tick borne encephalitis (TBE) is a viral infection which can also spread via the bite of infected ticks
    • toolkit aims to facilitate the implementation of locally driven tick awareness initiatives

Antibiotic treatment is highly effective, but approximately 10% of treated patients experience persistent symptoms (8).

Reference:

• (1) Dubrey SW et al. Lyme disease in the United Kingdom. Postgrad Med J. 2014;90(1059):33-42
• (2) Shapiro ED. Lyme Disease. The New England journal of medicine. 2014;370(18):1724-1731.
• (3) Centers for Disease Control and Prevention (CDC) 2020. Lyme disease
• (4) Public Health England. Guidance. Lyme borreliosis epidemiology and surveillance 2013
• (5) NICE (April 2018). Lyme disease.
• (6) Kullber BJ et al. Lyme borreliosis: diagnosis and management.BMJ 2020;369:m1041
• (7) Public Health England (June 2021). Managing common infections: guidance for primary care
• (8) Smith RS. Lyme Disease. Ann Intern Med.[Epub 13 May 2025].