"Hair" - what is it, definition of the term
The designation «Hair» denotes the keratinous filaments that originate from dermal follicles in mammals, forming a filamentous covering that contributes to protection, temperature regulation, and tactile perception, while also providing a substrate on which ectoparasites such as ticks, bugs, lice, and fleas may reside.
Detailed information
The filamentous covering of mammals consists primarily of keratinized protein strands that emerge from follicles embedded in the dermis. Growth follows a cyclical pattern: anagen (active elongation), catagen (transition), and telogen (resting). Each strand exhibits a median diameter of 17–180 µm, depending on species and body region. The outer cuticle layer provides mechanical protection and contributes to thermoregulation by trapping air.
Ectoparasites exploit this surface for attachment, feeding, and reproduction. Specific interactions include:
- Ticks: Attach to the shaft near the scalp using specialized mouthparts that penetrate the cuticle. Engorgement occurs over several days, during which the parasite ingests blood and transmits pathogens such as Borrelia spp.
- Bugs: Certain hemipterans insert proboscises between fibers to access capillary vessels. Their saliva contains anticoagulants that facilitate prolonged feeding.
- Lice: Nymphs and adults grasp the filamentous substrate with clawed tarsi, laying eggs (nits) cemented to the shaft. Lifecycle completion requires continuous access to the host’s blood supply.
- Fleas: Jump onto the covering, then move to the skin surface to bite. Their hind legs generate forces up to 100 times body weight, enabling rapid relocation across the filament network.
Control strategies focus on disrupting the habitat and eliminating the parasites:
- Regular removal of dead strands reduces shelter availability.
- Application of topical insecticides containing permethrin or pyrethrins targets attached organisms without damaging the keratin structure.
- Frequent washing with shampoos formulated with dimethicone interferes with the adhesive properties of nit cement, facilitating detachment.
- Environmental treatment of bedding and clothing with insect growth regulators prevents re‑infestation.
Maintaining the integrity of the filamentous covering while managing ectoparasite populations requires coordinated grooming, chemical, and environmental measures.