Visual examination for lice

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During a visual exam for head lice, the hair on the head is parted with the fingers so that the scalp can be seen. The health professional or child's parent looks for tiny live lice [about 3 mm (0.12 in.) to 4 mm (0.16 in.) long, or the size of a sesame seed]. If you are checking your child or someone else for lice, it may be helpful to use a handheld magnifying glass or have another person help you. The doctor may use a special light called a Woods lamp in a darkened room to see the lice better.

• Lice will move quickly to avoid light, so they may be difficult to see.
• Nits (eggs) are small and white or light brown. They are usually found on the hair shaft close to the scalp. They do not slide up and down the hair shaft.
• If eggs are found farther from the scalp, the person may have been infested with lice for some time. If the nits have already hatched, the empty egg cases may appear white.

Pubic lice may look like yellowish brown or gray specks or small scabs. They are smaller than head lice [about 1 mm (0.04 in.) to 2 mm (0.08 in.) long] and are wider than they are long.

Body lice and their eggs may be seen in the seams of clothing. They are usually not found on the body, although there may be small, red bumps on the skin where the lice have bitten. The lice look like large head lice and may be up to 4 mm (0.16 in.) long.

People with itching in areas of the body that are commonly infested with lice—the scalp, pubic area, or armpits—or anyone who has close contact with a person who has lice should do a self-exam or have someone help them look for lice and nits.

Schoolchildren may be routinely examined for lice.

Seeing lice or their eggs (nits) is enough to diagnose a lice infestation. Treatment is always needed to get rid of the lice.

People who have pubic lice are strongly encouraged to seek testing for other sexually transmitted diseases. Up to one-third of people who have pubic lice also have some other sexually transmitted disease.¹

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Citations

1. Mathieu ME, Wilson BB (2005). Lice (pediculosis). In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 6th ed., pp. 3302–3304. Philadelphia: Elsevier Churchill Livingstone.