Telling parents to keep their lice-infected children home from school is a waste of time and ineffective at stopping spread, the American Academy of Pediatrics says in a new guideline on head lice.

The AAP, in its first update to its lice guidelines since 2002, notes that head lice are not a health hazard. And it states that "no-nit" policies that keep kids with lice at home don't benefit anyone and "should be abandoned."

"A child should not be restricted from school attendance because of lice, because head lice have low contagion within classrooms," the report notes.

"International guidelines established in 2007 for the effective control of head lice infestations stated that no-nit policies are unjust and should be discontinued, because they are based on misinformation rather than objective science."

That position echoes a similar statement issued by the Canadian Paediatric Society in the lice position statement it issued last fall.

The AAP report also warns that lice are becoming resistant to the current pesticides used against them. They say that some of the prescription medications and over-the-counter products used to kill the bugs may no longer be effective in some areas because the nits have built up resistance.

"This resistance is not unanticipated, because insects develop resistance to products over time," the report says, adding: "The actual prevalence of resistance to particular products is not known and can be regional."

They say the first line of attack against lice should still be permethrins (like Nix) and pyrethrins (like Clear Lice System and Rid).

If these treatments don't work, there may be a number of reasons why, such as:

  • misdiagnosis (no active infestation or misidentification)
  • patient unable or unwilling to follow treatment protocol
  • not using enough of the product, to saturate hair
  • reinfestation
  • eggs not killed during the first treatments that can hatch and cause self-reinfestation
  • resistance of lice to the medication

Adult lice are about the size of sesame seeds and can be hard to spot because they move quickly. It's often easier to spot the nits: the small, empty egg casings that look like they could be dandruff but that are actually stuck to the hair.

The AAP advises that in cases of stubborn infestations that resist treatment, benzyl alcohol 5 per cent can be prescribed if the patient is older than 6 months, or malathion 0.5 per cent if the patient is older than 24 months, "and if safe use can be reasonably ensured."

The pediatricians also suggest that parents might want to try alternative treatments. "Wet combing," which involves wetting the hair with water or other fluids and combing out the lice and eggs with a fine-toothed "nit comb" is often perfectly effective. Another idea is to apply petroleum jelly to the hair, cover the head with a shower cap, letting it stay on overnight and into the next day as a way to suffocate the lice.

The Canadian Paediatric Society said in its position paper last year that it didn't think there was enough evidence that either of these approaches were effective.

As for disinfecting the house, the AAP states that "Herculean cleaning measures are not beneficial."

"Washing, soaking, or drying items at temperatures greater than 130°F will kill stray lice or nits. Furniture, carpeting, car seats, and other fabrics or fabric-covered items can be vacuumed," the report advises.

"Although it is rarely necessary, items that cannot be washed can be bagged in plastic for two weeks, a time when any nits that may have survived would have hatched and nymphs would die without a source for feeding," it adds.