What is Lyme disease caused by a tick bite? - briefly
Lyme disease is an infection transmitted to humans when an infected black‑legged (Ixodes) tick bites and injects the bacterium Borrelia burgdorferi into the skin. Early manifestations often include an expanding rash and flu‑like symptoms, and timely antibiotic treatment prevents serious complications.
What is Lyme disease caused by a tick bite? - in detail
Lyme disease is an infection caused by the spirochete Borrelia burgdorferi, which is transmitted to humans through the bite of infected hard‑ticks of the genus Ixodes (commonly the black‑legged or western black‑legged tick). The pathogen resides in the tick’s midgut and migrates to the salivary glands during feeding; transmission typically requires the tick to remain attached for at least 36 hours.
The disease occurs primarily in temperate regions of North America, Europe, and parts of Asia where competent tick species are established. Incidence peaks during late spring and summer, coinciding with the activity of nymphal ticks, which are small enough to go unnoticed.
Clinical presentation progresses through three overlapping stages:
- Early localized infection (3–30 days): erythema migrans rash expanding from the bite site, flu‑like symptoms (fever, chills, headache, fatigue, muscle aches).
- Early disseminated infection (weeks to months): multiple erythema migrans lesions, facial nerve palsy, meningitis, carditis, migratory joint pain.
- Late disseminated infection (months to years): chronic arthritis, predominantly affecting large joints; peripheral neuropathy; neurocognitive disturbances.
Diagnosis relies on a two‑tier serologic algorithm:
- Enzyme‑linked immunosorbent assay (ELISA) to detect antibodies against B. burgdorferi.
- Western blot confirmation of specific IgM and IgG bands if ELISA is positive or equivocal.
Polymerase chain reaction (PCR) testing may be used for synovial fluid or cerebrospinal fluid when serology is inconclusive.
Treatment recommendations:
- Early disease: oral doxycycline (100 mg twice daily for 10–21 days) or amoxicillin/cefuroxime for patients unable to take doxycycline.
- Neurological or cardiac involvement: intravenous ceftriaxone (2 g daily for 14–28 days).
- Late arthritis: oral doxycycline or cefuroxime for 28 days; intra‑articular corticosteroids may be considered for persistent joint inflammation after antimicrobial therapy.
Prevention strategies include:
- Wearing long sleeves and pants, tucking clothing into socks when in tick habitats.
- Applying EPA‑registered repellents containing DEET, picaridin, or IR3535 to skin and permethrin to clothing.
- Conducting full‑body tick checks after outdoor exposure; removing attached ticks promptly with fine‑tipped forceps, grasping close to the skin and pulling straight upward.
- Landscape management to reduce tick populations (removing leaf litter, keeping grass short, creating barrier zones).
Prompt recognition, accurate testing, and appropriate antimicrobial therapy markedly reduce the risk of long‑term complications from this tick‑borne infection.