Detection combing involves combing the hair with a special fine-toothed detection comb that has teeth spaced less then 0.3mm apart. This can be carried out on wet or dry hair. Wet combing requires more preparation, but is a more reliable method as lice become motionless when wet.

For wet detection combing:

• Wash hair using an ordinary shampoo, then apply plenty of conditioner. Use a wide-toothed comb to straighten and detangle the hair. Once the comb moves freely through the hair without dragging, begin using the louse detection comb
• Ensure the teeth of the comb slot in the hair at the roots and lightly touch the scalp
• Draw the comb down to the ends of the hair with every stroke and check the comb for lice
• Work methodically through the hair, section by section, until all the hair is combed through
• Rinse out the conditioner and repeat the procedure in the washed, wet hair.

For dry detection combing, repeat the above procedure on dry hair. Be cautious that as the comb is removed from the hair, lice may be repelled by static electricity.

The presence of nits indicates that lice were present at some time, but is not proof that the individual is currently infected. It is difficult to distinguish between nits that have hatched and those that still contain live lice. The closer the nits are to the scalp, the more likely it is that they are waiting to hatch.

Nits that are firmly attached to the hair shaft within a quarter of an inch of the scalp suggest, but do not confirm, a head lice infection. However, it is easy to confuse nits with dandruff or particles of hair styling products. 

If a live louse is found in the hair, this probably indicates an active infection. Parents should check the hair of every other member of the household, alert close friends and notify the child's school. There is no need to keep children with head lice off school. They may have had the infection for several weeks, so keeping them at home is unlikely to affect transmission.