How do ticks transmit infection? - briefly
Ticks become infected by feeding on hosts carrying pathogens; the microorganisms move from the tick’s midgut to its salivary glands and are introduced into a new host during later blood meals. Transmission can begin within minutes of attachment, depending on the pathogen’s location within the tick.
How do ticks transmit infection? - in detail
Ticks acquire microorganisms while feeding on infected hosts. During attachment, the mouthparts penetrate the epidermis and create a feeding cavity that connects to the tick’s salivary glands. Pathogens present in the host’s blood enter the tick’s gut, survive digestion, and migrate to the salivary glands.
Transmission occurs when the tick inserts its hypostome and releases saliva into the host. Saliva contains anti‑hemostatic, anti‑inflammatory, and immunomodulatory proteins that facilitate prolonged feeding and create a permissive environment for pathogens. As blood is drawn, microorganisms are expelled from the salivary ducts directly into the host’s dermal tissue.
Key mechanisms include:
- Salivary secretion – delivers spirochetes, rickettsiae, viruses, or protozoa into the bite site.
- Suppression of host defenses – inhibits clotting, complement activation, and cytokine signaling, allowing pathogens to evade immediate immune detection.
- Co‑feeding transmission – uninfected ticks acquire pathogens from nearby infected ticks feeding on the same host, independent of systemic infection.
- Transstadial persistence – pathogens survive through the tick’s developmental stages (larva → nymph → adult), maintaining infectivity.
- Transovarial passage – some agents are transferred from adult females to their eggs, infecting the next generation.
The probability of successful transmission rises with attachment time; many agents require at least 24–48 hours of feeding. Early removal of attached ticks reduces the risk of pathogen delivery.
Overall, the combination of specialized mouthparts, saliva‑mediated immunomodulation, and the ability of microorganisms to persist across life stages enables ticks to serve as efficient vectors of diverse infections.