What happens with a Borrelia‑infected tick? - briefly
After acquiring Borrelia, the tick carries the spirochetes in its salivary glands and can transmit them to a host during blood feeding, causing infection. The bacterium remains viable within the tick throughout its life stages, potentially influencing the tick’s survival and feeding behavior.
What happens with a Borrelia‑infected tick? - in detail
A tick that has acquired Borrelia during a previous blood meal carries the spirochete in its midgut. When the arthropod attaches to a new host, it inserts its hypostome and begins to ingest blood. Within the first 24 hours of feeding, the bacterial load in the midgut increases as the pathogen multiplies in response to the temperature rise and nutrient influx. Around 36–48 hours after attachment, spirochetes migrate from the midgut through the tick’s hemocoel to the salivary glands. This migration is facilitated by the expression of outer‑surface proteins (e.g., OspC) that enable the bacteria to detach from the midgut epithelium and enter the salivary ducts.
During the subsequent feeding phase, Borrelia is secreted with the tick’s saliva into the host’s skin. Salivary components suppress local immune responses, creating a microenvironment that favors bacterial transmission. The probability of successful inoculation rises sharply after the 48‑hour threshold; earlier removal of the tick dramatically reduces the risk of infection.
The presence of the pathogen also influences the tick’s physiology. Infected specimens display altered questing behavior, often extending attachment time to maximize transmission opportunities. Metabolic demands increase, reflected in higher expression of digestive enzymes and changes in gut microbiota composition.
If the tick is detached before spirochete migration, the pathogen remains confined to the midgut and does not reach the host. Removal techniques that grasp the tick close to the skin and apply steady traction minimize tissue damage and prevent regurgitation of infected gut contents.
Key stages of the process:
- Acquisition: ingestion of infected blood, colonization of the midgut.
- Replication: bacterial proliferation triggered by feeding cues.
- Migration: movement to salivary glands mediated by surface protein switches.
- Transmission: release into host during prolonged feeding.
- Host response: local immune suppression by tick saliva, leading to establishment of infection.
Understanding each step clarifies why prompt tick removal is critical and informs strategies for preventing the spread of Lyme‑associated disease.