Wszy

Wszy, commonly referred to as lice, are small parasitic insects of the order Phthiraptera that infest humans and other animals. In humans, the principal species of medical importance are Pediculus humanus capitis (head lice), Pediculus humanus corporis (body lice), and Pthirus pubis (pubic lice).

All three feed on blood and have a lifecycle that begins with the female laying eggs (nits) cemented to hair shafts. Nits hatch after about 7–10 days into nymphs, which molt three times before reaching adulthood. Lice typically survive for several weeks on a host, with females laying up to a few eggs daily. Their life cycles are influenced by temperature and humidity, and nits located far from the scalp are unlikely to hatch.

Transmission occurs via direct contact and, for body and occasionally head lice, through infested clothing or bedding. Pubic lice are mainly spread through sexual contact, but can also be transmitted via shared towels or bedding. Symptoms include localized itching and visible lice or nits on the hair or body. Scratching can lead to secondary bacterial infections.

Diagnosis relies on finding live lice or nits on the scalp or body, often aided by a fine-tooth comb. Distinguishing lice from dandruff or hair products is important.

Treatment involves pediculicidal products such as permethrin or pyrethrins with piperonyl butoxide, applied according to product instructions and sometimes repeated after 7–10 days. Mechanical removal with a fine comb and washing of clothing, bedding, and personal items at high temperatures help prevent reinfestation. In resistant cases, or where oral treatment is appropriate, ivermectin or other agents may be used where permitted.

Prevention focuses on avoiding sharing personal items, regular screening, and treating all contacts if an infestation is detected. Body lice, though less common in developed settings, can be associated with transmission of diseases such as epidemic typhus and relapsing fever in crowded or unhygienic conditions.