Act fast

“People are not treating an infestation at the earliest stages,” says Ian Burgess, the director of the Medical Entomology Centre in Cambridge, whose research is cited in the Nice guidelines for this persistent problem. “We quite often find people with hundreds and occasionally thousands of lice,” he says. Dee Wright, the owner of The Hairforce, a chain of self-styled “lice assassins”, says: “If you check your child’s hair and find a bunch of nits [eggs], you should be combing immediately, rather than waiting to spot a live one. It’s good to do a weekly check.”

Choose your weapon wisely

‘With thick or long hair, you need to spend 20 to 30 minutes per session.’ Photograph: Getty Images/iStockphoto

Many of Britain’s bestselling nit combs are ineffective, says Burgess: “They have gaps so wide that lice and nits can slip through.” He recommends using a plastic detection comb. “It needs to be rigid, and the front needs to be squared, to catch the legs of the lice.” The Bug Buster Kit sold by the charity Community Hygiene Concern contains these types of combs, with different sizes for lice and nits, and is available on the NHS (free for children diagnosed with lice). “It’s not going to be done in five minutes,” says Burgess. “With thick or long hair, you need to spend 20 to 30 minutes per session. If you’ve found a dozen and think you’ve done a good job, you probably haven’t – there’ll be at least another dozen hiding.”

Comb with care

Detangle the hair first and use conditioner. Photograph: Shinypix/Alamy

“Lice are movement-sensitive and scarper when you touch the hair,” warns Wright. Dividing the head into sections helps avoid missing any. Detangle the hair first and use conditioner. Metal combs, especially, can shred individual hairs, says Burgess. “We have even come across pseudo nits, where the comb has peeled back little knots that look and feel like nits,” he says. “So if you’re going to comb, you need to use a lubricant and do it carefully.”

Forget chemical pesticides

Burgess says that we have known about pesticide-resistant lice in the UK since 1995, yet chemical pesticide treatments are still sold – and frequently recommended by pharmacists and prescribed by doctors. “GPs aren’t listening,” he says. “It’s hardly surprising there are a lot of lice.”

Play the long game

Silicone-based shampoo treatments, otherwise known as physical pesticides, may effectively smother the lice, but some of the dreaded nits can survive. “We looked at nearly 1,895 case records,” says Burgess. “Most of those who had baby lice appear after a treatment had them within the first week, but the longest case was 13 days.” Either treat again a week or so later, or keep combing for a few weeks to catch any late hatchers.