How does a tick transmit Lyme disease to humans? - briefly
When an infected Ixodes tick attaches and feeds, it injects saliva that carries Borrelia burgdorferi into the skin, allowing the bacteria to enter the bloodstream. Transmission usually occurs only after the tick has remained attached for 36–48 hours.
How does a tick transmit Lyme disease to humans? - in detail
Ticks of the genus Ixodes acquire the spirochete Borrelia burgdorferi while feeding on infected reservoir hosts, typically small mammals such as white‑footed mice. The bacterium resides in the tick’s midgut and multiplies during the nymphal or adult blood meal. When the arthropod inserts its mouthparts into human skin, it secretes saliva that contains anticoagulants, immunomodulatory proteins, and enzymes facilitating prolonged attachment. These salivary components create a microenvironment that suppresses local immune responses and promotes pathogen migration.
The transmission sequence proceeds as follows:
- The tick attaches and creates a cement‑like attachment pad with its fore‑legs.
- Saliva is injected continuously throughout feeding; the feeding period for nymphs averages 48–72 hours.
- Borrelia cells detach from the midgut epithelium, traverse the hemocoel, and enter the salivary glands.
- Once in the saliva, spirochetes are delivered into the host’s dermis and disseminate via the bloodstream to peripheral tissues.
A minimum of 24–36 hours of attachment is required before spirochetes reach the salivary glands in sufficient numbers to cause infection. Prompt removal of the tick, preferably within this window, markedly reduces the risk of disease. After attachment, the pathogen spreads to joints, the heart, and the nervous system, producing the characteristic stages of Lyme disease.
Effective prevention focuses on avoiding tick habitats, using repellents, performing regular full‑body inspections, and removing attached ticks with fine‑tipped tweezers, grasping close to the skin to minimize mouthpart breakage. Proper disposal of the removed specimen prevents further exposure.