How is Lyme disease transmitted by a tick? - briefly
When an infected Ixodes tick attaches and feeds for 36–48 hours, Borrelia burgdorferi migrates from the tick’s midgut to its salivary glands and enters the host’s bloodstream. Removing the tick before this interval markedly lowers infection risk.
How is Lyme disease transmitted by a tick? - in detail
Lyme disease is caused by the bacterium Borrelia burgdorferi, which is introduced into a host during the blood‑feeding phase of the black‑legged tick (Ixodes scapularis or Ixodes pacificus). The pathogen resides in the tick’s midgut after the arthropod acquires it from an infected reservoir animal, most commonly the white‑footed mouse. When the tick attaches to a new host, it inserts its hypostome and secretes saliva containing anticoagulants and immunomodulatory proteins. These substances suppress the host’s immediate inflammatory response, allowing the tick to feed for several days.
During the later stages of feeding—typically after 36–48 hours—the spirochetes migrate from the midgut to the salivary glands. The bacteria are then expelled into the host’s skin together with the tick’s saliva. The longer the attachment, the greater the likelihood of transmission; removal within 24 hours reduces risk dramatically.
Key factors influencing the transmission process include:
- Tick developmental stage – Nymphs are most responsible for human infections because of their small size and high infection rates.
- Feeding duration – Transmission probability rises sharply after the first 24 hours of attachment.
- Environmental conditions – Warm, humid climates favor tick activity and increase exposure risk.
- Host immunity – Prior exposure to Borrelia may affect bacterial load but does not guarantee protection.
Understanding these biological steps clarifies why prompt tick removal and preventive measures, such as repellents and landscape management, are essential for reducing infection rates.