What does a tick inject into the body when biting? - briefly
A tick injects saliva that contains anticoagulants, anesthetic agents, and immunomodulatory proteins, and it can also transmit pathogens such as bacteria, viruses, and protozoa.
What does a tick inject into the body when biting? - in detail
Ticks introduce a complex cocktail of bioactive substances when they attach to a host. The primary purpose of this secretion is to enable prolonged blood ingestion while evading the host’s hemostatic and immune defenses. The composition of the injected material includes:
- Anticoagulants such as apyrase and a thrombin‑inhibiting protein that prevent platelet aggregation and clot formation.
- Anti‑inflammatory agents that suppress cytokine release, reducing swelling and redness at the bite site.
- Anesthetic peptides that numb the surrounding skin, allowing the parasite to feed unnoticed.
- Immunomodulatory proteins, for example Salp15, which interfere with complement activation and T‑cell signaling.
- Enzymes that degrade extracellular matrix components, facilitating probe penetration and fluid flow.
- Pathogenic organisms that may be present in the tick’s salivary glands, including spirochetes (e.g., Borrelia burgdorferi), rickettsiae, Anaplasma species, and certain viruses. These microbes are transferred to the host together with the saliva.
The volume of this secretion is minute, typically measured in nanoliters, but it is delivered continuously over several days of attachment. Different tick families vary in the exact repertoire of salivary factors; hard ticks (Ixodidae) generally secrete a more diverse set of immunosuppressive proteins compared with soft ticks (Argasidae). The combined effect of these substances creates a localized environment that suppresses clotting, blunts pain perception, and dampens immune detection, thereby facilitating successful blood feeding and potential pathogen transmission.