Diagnosing Head Lice
When diagnosing head lice, a person's hair and scalp must be closely examined for nits, nymphs, or adults. This can be difficult, as there may only be a few nymphs or adults present, and they can move quickly through a person's hair. If there is uncertainty when diagnosing head lice, it's a good idea to check with schools or childcare centers to see if recent infestations have been reported.
Parents may suspect head lice if their child is complaining of an itching head or neck, or if they see small, red sores. However, head lice is diagnosed by looking closely through the hair and scalp for nits, nymphs, or adults. Finding a nymph or adult may be difficult; there are usually few of them, and they can move quickly from searching fingers.
If crawling lice are not seen, finding nits within a ¼ inch of the scalp confirms that a person is infested and should be treated. If you only find nits more than a ¼ inch from the scalp (and don't see a nymph or adult louse), the infestation is probably an old one and does not need to be treated.
Nits and adult head lice are usually visible to the naked eye, but a hand lens or light may help.
If you are not sure if a person has head lice, a diagnosis should be made by your healthcare provider, school nurse, or a professional from the local health department or agricultural extension service.
Also, it is a good idea to check with the school nurse or childcare center to see if anyone has been recently treated for head lice.