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TORONTO — School is back in session and some parents will soon be getting calls alerting them to the fact that someone in their child’s class has lice. Or perhaps your own child has been found to have lice, which can be very disturbing.
So I thought it would be a good time to talk about lice.
The scientific term for a louse is Pediculus, and it’s a 3 to 4 mm insect with legs adapted to grab hair and a mouth adapted to suck blood.
Females lay sevens to 10 eggs per day (called “nits”), these hatch eight to 10 days later into “nymphs” and reach adulthood 8-15 days after that. And the cycle starts again.
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The first point I want to make is that lice infestation has nothing to do with a personal hygiene or cleanliness.
After the common cold, it’s actually the most common communicable disease seen in elementary school kids.
Girls tend to get lice more than boys, which may have to do with hair length, though the studies on that are not conclusive.
How are they transmitted? Several scientific studies have looked at how far lice can travel and how they spread.
As it turns out, they don’t fly and they don’t jump — they simply crawl — which means that transmission mostly occurs through direct contact with an infected person’s head.
That being said, studies have now confirmed that lice can be dislodged by air movements such as blow-drying, as well as combing and towelling. Less than five per cent of the time lice will also be found on pillowcases.
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The good news is that they can only survive about 55 hours without a host.
To get rid of them, wash towels and bedding in hot water (at least 66 C), dry them on the hottest setting and put combs or anything else that can’t be washed in a sealed plastic bag for two weeks.
How will you know if your child has lice?
Some kids will have an itch or skin irritation of the scalp, neck, and ears, which is actually from an allergic reaction to the louse’s saliva, but amazingly, most kids have no symptoms at all from lice.
So you have to find them.
And the best way to do that is to comb through wet hair with a fine comb, starting near the crown, gently touching the scalp, drawing firmly down, and doing this systematically to cover the whole head at least twice, while examining the comb for lice or nits — which are lice eggs — with every stroke.
This is made easier with the help of a Wood’s lamp, which makes the nits fluoresce in blue. But remember that dead nits can stay on hair for months after lice have cleared, so nits alone do not mean active infection.
Finally, what do you do to get rid of lice?
The first line approach is permethrin or pyrethrin-based insecticide shampoo performed once and repeated seven to 10 days later, using cool water with the child’s head over a sink or tub.
However, a Canadian study by D. Marcoux and colleagues published in the in the Journal of Cutaneous Medicine and Surgery in 2010 showed that 97.1 per cent of lice colonies collected from patients in Ontario, Quebec, and British Columbia had a gene mutation which confers permethrin resistance.
READ MORE: Tips to treat head lice and prevent reinfestation
In a 2014 study, the same group then reported that the mutation was found in 99.6 per cent of U.S. samples.
This is a worldwide resistance pattern that has likely developed due to widespread use of these insecticides.
That being said, the presence of this gene does not necessarily mean that these agents will be completely ineffective.
In cases of treatment failure, other shampooed insecticides, such as Lindane, can be considered (although this agent is not safe in young kids).
Some non-insecticide agents have also been found to be effective in small studies, and other studies are ongoing.
In rare cases, oral medications such as Ivermectin or Trimethoprim-sulfamethoxazole may be required.
Unfortunately, home remedies like olive oil and petroleum jelly have been studied and are not effective.
What about returning to school?
Many school districts will send kids with lice home and ask them not to return for an extended period of time.
However, medical societies across the world, including the Canadian Pediatrics Society discourage this approach.
The fact is that the lice were probably there for weeks prior to detection anyways, the infections are rarely serious, and the majority of children will not catch it.
The key is that affected children avoid direct head contact with other individuals and should be treated promptly, along with careful management of inanimate objects that are in contact with student’s heads at school.
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