What causes itching because of lice? - briefly
The itch arises when lice bite the scalp and inject saliva, to which many people react with a localized allergic response that causes redness and swelling. Additional irritation can occur if the bite sites become infected or are scratched repeatedly.
What causes itching because of lice? - in detail
Lice infestations trigger itching primarily through the body’s reaction to substances injected by the parasites. When a louse feeds, it pierces the skin and releases saliva that contains anticoagulants and enzymes. These foreign proteins are recognized by the immune system, leading to the release of histamine and other inflammatory mediators. Histamine dilates blood vessels and stimulates nerve endings, producing the characteristic pruritus.
The intensity of the sensation varies with several factors:
- Individual sensitivity – some people develop a stronger allergic response to louse saliva, resulting in more pronounced itching.
- Number of insects – heavier infestations increase the cumulative amount of saliva deposited, amplifying the immune reaction.
- Location of bites – areas with thin skin, such as the scalp, neck, and groin, are more vulnerable to irritation.
- Secondary bacterial infection – scratching damages the epidermis, allowing bacteria to enter and cause additional inflammation and itch.
Mechanical irritation also contributes. The movement of lice across the hair shafts and the presence of nits (eggs) create friction that can stimulate cutaneous nerves. In addition, the buildup of debris, such as dead lice and skin scales, can act as a physical irritant.
In summary, itching associated with lice results from a combination of allergic inflammation to salivary proteins, the physical presence of the insects and their eggs, and possible secondary infection caused by scratching. Managing the infestation promptly and treating the inflammatory response are essential to alleviate the discomfort.