How does a tick infect? - briefly
Ticks attach to the host’s skin, create a feeding cavity, and inject saliva that carries infectious agents. While the tick remains attached for several days, the agents move from the saliva into the host’s bloodstream.
How does a tick infect? - in detail
Ticks attach to a host by inserting their hypostome, a barbed feeding organ, into the skin. Cement proteins secreted from the mouthparts secure the attachment for several days, allowing continuous blood ingestion.
During feeding, the tick releases a complex mixture of bioactive compounds from its salivary glands. These include anticoagulants, immunomodulators and anti‑inflammatory agents that suppress host defenses and maintain blood flow. Pathogens present in the tick’s midgut migrate to the salivary glands, where they become incorporated into the saliva.
Transmission occurs through two principal mechanisms:
- Biological transmission – pathogens replicate within the tick, undergo developmental changes in the midgut and salivary glands, and are delivered to the host during prolonged feeding. Examples include Borrelia burgdorferi (Lyme disease), Anaplasma phagocytophilum and tick‑borne encephalitis virus.
- Mechanical transmission – pathogens are carried on the tick’s mouthparts or in regurgitated blood without replication inside the vector. This route is less common but can convey agents such as Rickettsia spp.
The efficiency of pathogen transfer depends on several factors: duration of attachment, developmental stage of the tick (larva, nymph, adult), pathogen load in the vector, and the host’s immune status. Nymphal ticks often transmit diseases more effectively because their small size facilitates unnoticed feeding for extended periods.
Environmental conditions influence tick activity and infection rates. Warm, humid climates accelerate questing behavior and increase the likelihood of host encounters, thereby raising transmission potential. Seasonal peaks correspond to the life‑cycle timing of the vector species.