Head lice infestation | |
---|---|
Other names | Pediculosis capitis,[1] nits,[2] cooties[3] |
Head lice on long hair | |
Specialty | Pediatrics, infectious disease |
Symptoms | Itching that can result in trouble sleeping[4][5] |
Usual onset | Up to six weeks from infestation[5] |
Causes | Head louse spread by direct contact[4][6] |
Diagnostic method | Finding live lice[5] |
Treatment | Combing the hair with a fine tooth comb, shaving the head, medications[7] |
Medication | Malathion, ivermectin, dimethicone[7] |
Prognosis | Not serious[7] |
Frequency | Common[5] |
Head lice infestation, also known as pediculosis capitis, is the infection of the head hair and scalp by the head louse (Pediculus humanus capitis).[6] Itching from lice bites is common.[5] During a person's first infection, the itch may not develop for up to six weeks.[5] If a person is infected again, symptoms may begin much more quickly.[5] The itch may cause problems with sleeping.[4] Generally, however, it is not a serious condition.[7] While head lice appear to spread some other diseases in Africa, they do not appear to do so in Europe or North America.[6][4]
Head lice are spread by direct contact with the hair of someone who is infected.[4] The cause of head lice infestations in children is not related to cleanliness.[5] Other animals, such as cats and dogs, do not play a role in transmission.[4] Head lice feed only on human blood and are only able to survive on human head hair.[6][5] When adults, they are about 2 to 3 mm long.[8] When not attached to a human, they are unable to live beyond three days.[5] Humans can also become infected with two other lice – the body louse and the crab louse. To make the diagnosis, live lice must be found.[5] Using a comb can help with detection.[5] Empty eggshells (known as nits) are not sufficient for the diagnosis.[5]
Possible treatments include: combing the hair frequently with a fine tooth comb or shaving the head completely.[7] A number of topical medications are also effective, including malathion, ivermectin, and dimethicone.[7] Dimethicone, which is a silicone oil, is often preferred due to the low risk of side effects.[7] Pyrethroids such as permethrin have been commonly used; however, they have become less effective due to increasing pesticide resistance.[7] There is little evidence for alternative medicines.[9]
Head-lice infestations are common, especially in children.[5] In Europe, they infect between 1 and 20% of different groups of people.[6] In the United States, between 6 and 12 million children are infected a year.[4] They occur more often in girls than boys.[5] It has been suggested that historically, head lice infection were beneficial, as they protected against the more dangerous body louse.[10] Infestations may cause stigmatization of the infected individual.[5]