What are lice?
Lice are wingless, blood-sucking insects that infest the head, body, or pubis. The 3 kinds of lice are very different from one another. Head lice and pubic lice live directly on the host; body lice live in garments. All types occur worldwide. This article will focus on head lice.
Common features of head lice
Head lice are most common among girls aged 5 to 11 but can affect almost anyone. Head lice are easily transmitted from person to person with close contact (as occurs within households and classrooms) and may be ejected from hair by static electricity or wind; transmission by these routes (or by sharing of combs, brushes, and hats) is likely but unproved. There is no association between head lice and poor hygiene or low socioeconomic status.
Infestation usually involves the hair and scalp but may involve other areas with hair. A lice infection usually involves no more than 20 lice and is very itchy. The lice are not easily able to be seen.
Lice are usually found at the back of the head or behind the ears. Nits are more commonly seen and are oval shape, grayish white eggs fixed to the base of hair shafts. Each adult female louse lays 3 to 5 eggs each day, so there typically way more eggs than lice. The number of nits found does not tell us how bad the infection is.
How are lice infections treated?
There are several approaches to treatment. We recommend speaking with your doctor for recommendations.
One common approach is oral ivermectin along with a shampoo called permethrin. Wash hair first, then apply medicated shampoo to wet hair, behind ears and on nape; wash off in 10 min.
May repeat in 7 days if live nits (closer than a 1/4 inch away from the scalp) are seen.
After using the shampoo, nits are removed by using a fine-tooth comb on wet hair (wet combing). Killing or removal of live nits is important in preventing reinfestation. Permethrin is usually effective at killing live nits. Dead nits remain after successful treatment and do not have to be removed. Nits grow away from the scalp with time; the absence of nits less than one fourth of an inch from the scalp rules out current active infection. Hot air has been shown to kill more than 88% of nits as well. Thirty minutes of hot air, slightly cooler than a blow dryer, may be an effective adjunctive measure to treat head lice.
It is not clear as to the need to clean personal items of people with lice or nits and the need to exclude children with head lice or nits from school. Some experts recommend replacement of personal items or thorough cleaning, followed by drying at 130° F for 30 min. Items that cannot be washed may be placed in airtight plastic bags for 2 weeks to kill the lice, which live only about 10 days.
Jesse Bradshaw PA-C