How do you know if you’ve got head lice?
According to Public Health England (PHE), the only reliable way to diagnose an active infestation is to find a living, moving louse. This is because the eggs of lice (nits) can be mistaken for dandruff or hair muffs – oily secretions that can wrap around hair – and even if you do find a nit, it is difficult to tell whether it is dead or alive. Not everyone with head lice will experience an itchy scalp, and itchiness could be psychological, or the result of something else, such as eczema. The best way to find a living louse is through combing: it’s nearly four times more effective than simply ruffling through the hair and spotting one with the naked eye.
Do I need an expensive comb?
Many combs marketed for the removal of lice or nits aren’t fit for purpose, says Ian Burgess, president of the International Society of Phthirapterists (people who study lice): “Either the teeth are too far apart; they’re constructed from flimsy plastics; or they have inconsistently arranged teeth.” The ideal detection comb is a plastic one with flat, parallel teeth less than 0.3mm apart. There is no evidence that double layers of teeth or electric combs are more effective, Burgess says.
Combing should be performed on damp hair, in good light, and applying conditioner makes it easier. Start at the top of the head with the teeth of the detection comb touching the scalp, and gently draw the comb downwards, looking carefully at the teeth for the sesame seed-sized insects.
I’ve found a louse – what do I do now?
Many of the treatments you’ll find in your chemist are based on an oily substance called dimeticone. This physically blocks the holes through which lice breathe, suffocating them – rather than poisoning them, as older insecticides such as permethrin or malathion did. “Some populations of head lice have developed resistance against insecticides, so these tend not to be the best treatments anymore,” says James Logan, scientific director of the Arthropod Control Product Test Centre at the London School of Hygiene and Tropical Medicine. Because dimeticone acts as a physical barrier, lice are unlikely to develop resistance to it, but it still only works around 80-90% of the time. The key is to thoroughly soak the hair with product, and then re-treat a week later to catch any newly hatched lice.
What about non-chemical treatments?
You could try wet-combing with conditioner and a series of fine-toothed combs, such as those found in so-called “bug buster” kits. Done properly, this clears head lice in 57% of cases, but it involves thoroughly combing the hair four times in the space of two weeks. For long, curly hair, this could mean 30 minutes each time. “Most caregivers are not that dedicated,” Burgess says.
Companies exist that will physically remove head lice using a kind of vacuum cleaner. “With big infestations, this can be a good way to at least bring numbers down, and can be helpful if you can’t get other treatments to work,” says Logan. You could also try tea tree oil, which poisons lice – although it only seems to be effective at concentrations upwards of 10%, at which point it may start to irritate the skin. “Most tea tree shampoos and conditioners contain less than 1% tea tree oil so would have no effect on lice,” says Burgess.
My child refuses to let me comb her hair. What can I do?
“Unfortunately, one of the things small children dislike more than anything is having their hair combed,” says Wendy Nicholson, lead nurse for children, young people and families at Public Health England. She advises distraction techniques, such as getting someone to read them a story, as well as building combing into their regular routine. Engaging children in louse detection can prove effective: get children to comb their dolls’ hair for imaginary lice; suggest they write a story or shoot a film about them; if they like science, encourage them to look at dead lice through a magnifying glass. “Follow their interests,” Nicholson says.
Is it true that head lice can jump, and do they really prefer clean hair?
No; this idea may have come about because the static electricity generated through combing dry hair can cause lice to be flicked into the air. Neither can they swim, fly or hop – they walk from head to head, during physical contact. If they become detached from the head they are vulnerable, and their eggs need to be kept warm, so you’re also unlikely to catch head lice from bedding or from the backs of chairs. “Head lice usually feed on blood every five hours; if they’re removed from the head, they quickly start to become very ill and weak,” explains Logan.
As for preferring clean hair, “this is a myth created in the late 1970s to convince middle-class families that they too could catch lice,” says Burgess. “If your hair is gunked-up, lice don’t particularly like it, but they can survive as long as they can feed.”
My child keeps becoming infested: is there anything we can do to deter them?
There’s some limited evidence that tea tree and lavender oil repel head lice, but larger studies are needed, says Logan. The key things are to notify your child’s school if you detect head lice, encourage parents of close friends to check and treat their children, and regularly check your own child’s hair. “Detection at the earliest stage is most important,” says Burgess. Ideally, you want to kill lice before they get the opportunity to lay their eggs.
