What is a tick? - briefly
A tick is a tiny arachnid that attaches to the skin of vertebrates to obtain blood meals. It serves as a vector for various pathogens, including bacteria, viruses, and protozoa.
What is a tick? - in detail
Ticks are obligate ectoparasites belonging to the subclass Acari, order Ixodida. Their bodies consist of a capitulum containing the mouthparts and a idiosoma that houses the digestive and reproductive organs. The dorsally situated scutum provides protection, while the ventral surface bears sensory organs and attachment pads.
The developmental sequence includes four stages: egg, larva, nymph, and adult. After hatching, each stage seeks a vertebrate host for a blood meal, then detaches to molt. Larvae and nymphs typically feed on small mammals or birds; adults prefer larger hosts such as deer, livestock, or humans. Completion of the cycle requires a blood meal at each active stage.
Feeding involves insertion of the hypostome into host tissue, secretion of anticoagulant saliva, and prolonged engorgement lasting from hours to days. Salivary compounds suppress host immune responses, facilitating pathogen transmission. Commonly transmitted agents include Borrelia burgdorferi (Lyme disease), Rickettsia rickettsii (Rocky Mountain spotted fever), and Anaplasma phagocytophilum (human granulocytic anaplasmosis).
Key species of medical importance:
- Ixodes scapularis (blacklegged or deer tick) – primary vector of Lyme disease in North America.
- Dermacentor variabilis (American dog tick) – transmitter of Rocky Mountain spotted fever.
- Rhipicephalus sanguineus (brown dog tick) – vector for several bacterial and viral agents affecting dogs and humans.
Health impact arises from both direct blood loss and pathogen delivery. Prevention strategies focus on habitat management, personal protective measures, and prompt removal of attached specimens. Effective removal requires grasping the tick close to the skin with fine‑pointed tweezers, pulling steadily without crushing the body, and disinfecting the bite site. Early detection and proper handling reduce the risk of infection and limit disease severity.