Science

When fighting lice, focus on kids heads, not hats or toys

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I recently attempted a technically demanding “around the world” braid on my kindergartner. On my sloppy and meandering approach to the South Pole, I discovered a loathsome sight that scuttled my circumnavigation — a smattering of small, brownish casings stuck onto hairs.

I tried to convince myself that I was looking at sand. Shes always covered in sand! But Ive spent enough time around insects to know that I was looking at something biological. Bad braid abandoned, I began combing through, looking for more specks. And I sure found them: Lice eggs, or nits, that were glued onto the hair next to the scalp, and precisely one live bug.

Today, I am delighted to report that our outbreak is over. (Although with three young children, our situation will probably swing between “having lice” and “waiting to have lice again.”) Our first brush with the little buggers sent me into full research mode, and Im now armed with a deeper understanding of lice habits and preferences. In the interest of streamlining your next lice experience, I offer below some little-known and helpful facets of lice life.

The best way to spot lice and their tiny nits is with wet combing.

Compared with spot-checking the scalp, pulling a fine-toothed metal comb through hair thats slick with conditioner turns out more critters.

Pepper-sized nits can range from white to brown in color and are glued to single hairs. These suckers are on tight: You might need a fingernail to pop them off. Live nits need to be close to the warm scalp to survive; casings that are farther than a centimeter away from the scalp are probably empty or contain dead eggs.

Once hatched, a live human head louse, or Pediculus humanus capitis, grows no larger than the diameter of a pencil eraser. Its grayish white. And its favorite — and only — food is blood from a human scalp, which it slurps several times a day.

Super lice laugh at pesticides.

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More and more lice can withstand permethrin or pyrethrins, the pesticides inside most of the boxes youll find in your panicked drugstore run. And theres not much evidence for other treatments, including mayonnaise and tea tree or lavender oil. And please dont even think about gasoline.

An emerging favorite treatment is a silicone-based gel thought to smother lice and their eggs. Called dimethicone (also spelled dimeticone), it outperformed permethrin in one head-to-head test conducted by a team of researchers (that included scientists who had consulted for a lice treatment company). Because it works by physically coating the bugs, the treatment is unlikely to lead to more resistance.

Lice burrowed onto heads are surprisingly hardy, even underwater.

In one series of experiments, researchers watched lice cling to cut hair in regular water, seawater, salt solutions and even chlorinated water. The pests didnt respond to a poke, either, researchers found.

Another study looked at lice pulled off the heads of people in France. After six hours underwater, all the lice in the experiment (188 of them) were happily alive. About half of the lice were still alive after 24 hours underwater. Hardy, I say.

But: Lice are wusses when not on a head.

Off their favorite spot, adult lice quickly dry out and starve, particularly in dry environments. Most are dead within 40 hours after their last meal. And it is unlikely that eggs removed from a head can yield healthy adults.

Lice arent all that contagious.

They cant jump, fly or swim. Their dire need for a human head means that direct head-to-head contact, such as the type you see with little girls coloring together, is what allows lice to crawl to a new home.

“The control of head lice should focus on the head, not on the environment,” researchers wrote in 2010 in The Open Dermatology Journal. That paper mentions a study of over 1,000 hats, worn by students who, combined, had over 5,500 lice on their heads. The heads had lice, but the hats didnt. The risks of trRead More – Source