Lice infection is classified into 3 groups based on the the type of louse and its preferred location of infection: head lice, body lice and pubic lice.  All three are small bug-like parasites that infect human hair or clothing causing intense itching. Lice infestation is common in children of all ages.

What causes lice infection?

Head lice - Pediculus humanus capitus, a parasite 2-4 millimeters in length

Body lice - Pediculus humanus capitus, a parasite 2-4 millimeters in length

Pubic lice - Phthirus pubis, a parasite 1-2 millimeters in length with a "crab-like" appearance

How is lice spread?

Head lice is very contagious when children play together, coming in contact with hair and clothing.  Lice can survive for 1-2 days on combs, pillows, bedding, stuffed animals, clothing and furniture.  Female lice live for about 1 month and lay approximately 3-10 eggs per day.  The eggs are strongly attached to hair follicles as "nits" which are difficult to remove with a comb or by hand.

Body lice infection is rare in children, except for those in dirty living conditions and who rarely change clothes or bedding.

Pubic lice or "crabs" are spread by intimate contact.

What are the symptoms of head lice infection?

Scalp itching is the major symptom. 

Some children may have NO symptoms if infection is minor.

Occasionally the scalp may become irritated and infected with bacteria if the child is scratching aggresively.

Infection is not dangerous, but itching can be very uncomfortable.

How is lice infection diagnosed?

The diagnosis is often suspected based on a history of intense scalp itching.  The "nits," or small transluscent eggs that are glued to hair fibers can be seen without a magnifying glass or microscope.  Adult lice may be seen on occassion, however they move quickly and hide effectively in the hair and on the scalp.

How is lice infection treated?

Permethrin and Pyrethrin-based products are over-the-counter lotions and shampoos that can be applied to the hair and scalp for about 10 minutes and then rinsed.  A repeat application is recommended in 1 week to kill the newly-hatched lice, since lice eggs are resistant to these medicines.

Lindane and Malathion and prescription medications that are reserved for lice infestations that are resistant to over-the-counter medicines.

Photo - This is an illustration of the life cycle of Pediculus humanus capitis, the causal agent of Head Lice.  CDC/Alexander J. da Silva, PhD/Melanie Moser. 2002. Used with permission.