Pediculosis capitis and nits, commonly known as head lice infestation is the infection of the head scalp and hair by the Pediculus humanus capitis parasite. The head louse can live on people’s eyelashes and eyebrows as well.
During the first infection, the itching may not begin for up to six weeks. When a person is infected again, itch may begin much sooner than the first time. Head lice have to feed on human blood several times a day; this is why they live so close to the scalp.
According to the Journal of Parasitology, head lice originally appeared in North America, but spread across the world, including Europe and Australia. According to reliable sources, there are more than three thousand species of lice.
Humans host only two species: Pediculus humanus (head lice) and Phthirus pubis (pubic lice). Head lice group includes two morphotypes, head lice, and body lice. Presumably, the head louse is the ancestor of body louse that originated from the head and spread to the body when humans began to wear clothes.
Most treatments to kill off head lice need to be used twice, but seven to 10 days apart. It is recommended to comb a wet hair with a fine-toothed comb to remove nits. Some lice are resistant to common lice treatments that include pyrethrins and permethrin. This is when stronger prescription drugs are needed, such as spinosad or ivermectin.