When a tick bites, what is injected? - briefly
Ticks inject saliva that contains anticoagulants, anesthetic compounds, and immunomodulatory proteins to facilitate blood feeding and may also deliver pathogens such as bacteria, viruses, or protozoa. This salivary cocktail suppresses host defenses and can cause disease transmission.
When a tick bites, what is injected? - in detail
A tick introduces a complex mixture of biologically active substances through its mouthparts while it feeds. The primary vehicle is saliva produced in the tick’s salivary glands, which is deposited into the host’s skin along with the blood meal.
The salivary cocktail contains several functional groups:
- Anticoagulants – molecules such as apyrase and tick‑derived thrombin inhibitors prevent clot formation, keeping blood fluid.
- Anesthetics – compounds that reduce pain perception, allowing the tick to remain undetected.
- Immunomodulators – proteins that suppress local immune responses, including complement inhibitors and cytokine‑binding factors.
- Enzymes – proteases and lipases that facilitate tissue penetration and digestion of the blood meal.
- Pathogen vectors – bacteria (e.g., Borrelia burgdorferi), viruses (e.g., tick‑borne encephalitis virus), and protozoa (e.g., Babesia spp.) that may be transmitted alongside the saliva.
During attachment, the tick’s hypostome pierces the epidermis and inserts a feeding tube. Saliva is secreted continuously throughout the feeding period, which can last from several hours to days. The composition of the saliva changes over time, with early feeding dominated by anticoagulants and later phases enriched in immunosuppressive agents to sustain prolonged blood intake.
The injected substances collectively enable the tick to feed efficiently while minimizing host detection and creating a favorable environment for any accompanying microorganisms to establish infection.