Cause

Lice are very easily spread, usually through close personal contact. Lice infestation may be caused by any of the three types of lice:

• Head lice may be spread through close personal contact, shared personal items (combs, brushes, hats, helmets, clothing, or earphones), or shared bedding.
• Pubic lice are spread mainly through sexual contact and are very contagious. Most people become infected after a single exposure to an infected person. The lice and eggs may also survive long enough on personal items such as clothing or towels to be spread to another person. A child who has pubic lice may have a history of sexual abuse.
• Body lice are most often spread by contact with personal items, especially clothing and hats. They are sometimes spread by direct personal contact.

Lice are spread from human to human. Pets don't get head lice and can't spread them to humans.