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Heads Up Nitpickers

When it comes to lice, one thing we can count on is controversy:
Is it true these insects have become resistant to lice shampoos?
Do any of the alternative treatments work?
Are no-nit policies effective?

By John Hoffman


What we've heard
For five years or more, parents, teachers, camp directors and daycare operators have been saying lice have grown resistant to pediculicide shampoos - the standard drugstore remedies. Other experts say the big problem is people aren't using the pro-ducts properly, and kids are becoming reinfested after treatment.

Now scientific evidence shows parents and others were right. If you do a Google search on head lice, the first two sites that come up are the National Pediculosis Association (NPA), a Massachusetts-based non-profit group that's against lice shampoos like Nix and R&C, and the Harvard School of Public Health. Harvard entomologist Richard Pollack was lead author of a recent, well-publicized study on the resistance of lice to permethrin-based shampoos. (Permethrins are the synthetic equivalents of pyrethrins, pesticides derived from chrysanthemum flowers. These are the active ingredients in most lice shampoos used in North America.)

Here's what Pollack posted on the Harvard site: "Head lice sampled from children who were chronically infested and treated multiple times with pyrethroid shampoos tend to be resistant to permethrin." However, he also says, "This should not be interpreted as meaning that all (or even most) head lice are resistant to permethrin and related compounds. Permethrin and pyrethrins remain the treatment of choice for newly identified infestations."

On the other hand, Deborah Altschuler, executive director of the NPA, says there is no grey area. "Tests have shown that lice from American children are solidly resistant to permethrin."

John Clark, an entomologist and pesticide toxicologist at the University of Massachusetts, has also studied the resistance of lice to permethrin and he says that not only is the resistance there, it's likely to increase. "In our study, lice sampled from Panama, where permethrin is not used, succumbed to it very quickly, but 50 to 80 percent of the American lice either survived or took a lot longer to die, which suggests a significant number would survive normal treatment." Clark adds, "Obviously, neither our study nor the Harvard one sampled the entire louse population of the US, but we did look at children from five different towns and found similar resistance in all cases. And studies from the UK, Argentina, the Czech Republic, France and Israel have found the same thing - in fact, those countries appear to be ahead of us in terms of resistance.

"We've seen this happen with many other pesticides in the agricultural sector," he continues. "The farmers would say the products aren't working and the pesticide companies would say, 'You're not using the products properly.' What happens is that some lice are resistant to begin with and they, obviously, tend to survive treatments that are not 100 percent effective. So when you use pesticides in this situation, you are essentially selecting the few resistant ones that exist naturally to reproduce the next generation. The proportion of resistant bugs tends to increase over time. We saw that in agriculture and the same thing has happened with lice treated with permethrin."

What we know
Pyrethrin- and permethrin-based shampoos kill some lice, but there is good reason to believe they won't kill all the lice, all the time. Neither will shampoos containing lindane, another pesticide; these are still available over the counter in Canada, although they have largely been abandoned because permethrin is considered safer. (Lindane has been banned in California for treating lice and scabies, and in some 40 countries due to environmental concerns about its use as an agricultural pesticide.)

Bottom line
Lice shampoos alone won't do the job.


What we've heard
Most alternative treatments are shampoos based on herbs or essential oils - tea tree oil, for example - which claim to kill or immobilize lice. Some purport to have enzymes or other substances that loosen the glue that keeps the nit stuck to the hair shaft. Then there are the wacky products, like Neon Nits. This is a spray that reportedly makes the nits glow so they're easier to see. The Robi Comb is an electric nit comb that claims to kill lice with electric impulses.

Picton, Ontario, resident Wendy Oakley is one of a number of entrepreneurs who have developed their own products. Her Thursa Herbal Shampoo is a concoction of cider vinegar, five culinary herbs, Castile soap and a vegetable shampoo. Oakley says she got the idea from an old herb book that belonged to her mother. "This is based on remedies they used in the Middle Ages," she says. Oakley can't quite explain why her product works, but says, "It stuns the lice so they stand up on end on the hair shaft and the cider vinegar collapses the nits. So both lice and nits are easier to remove."

Neither Pollack nor Altschuler have tested Oakley's product, but they are skeptical of most similar claims. Altschuler has had some products tested by experts on animal adhesives, and has yet to find one that's unlocked the secrets of nit glue. Pollack concurs: "I've performed some limited work to evaluate the claims that certain products dissolve or degrade the glue; I remain unimpressed."

Some people have reported success drowning lice by applying olive oil, mayonnaise or Vaseline to the hair and leaving it there for several hours, usually covered with plastic. These theories haven't been clinically tested, although Bernice Krafchik, a paediatric dermatologist at Toronto's Hospital for Sick Children, says almost anything that plugs the spiracles (breathing holes) of lice may kill or incapacitate them. Some products like olive oil may ease nit removal, not because they loosen the glue, but because they help a nit comb go through the hair.

What we know
In the absence of clinical trials, as is the case with most of these treatments, it's difficult for consumers to tell which, if any, actually work, and whether they are any safer than lice shampoos. These, at least, have been subjected to clinical scrutiny.

Bottom line
Buyer beware. Check the product out. Has it been tested? Ask to speak to a satisfied customer. If it makes health claims, it should have a DIN (drug identification number), otherwise it has not been approved by Health Canada for therapeutic use.


What we've heard
Some observers say lice infestations are epidemic, but Pollack maintains misdiagnosis is common, and many children are treated unnecessarily. "It seems clear to me that the most frequently treated kids - and adults - don't have lice in the first place," he says. Pollack's lab invited people to send in samples from suspected lice cases. He found that almost 40 percent of the samples were either hair debris mistakenly identified as nits or, to a smaller extent, other bugs (book lice, mites, bedbugs, etc.). Of the real nits, about half were either hatched or contained a dead embryo and were therefore incapable of producing a live louse. Overall, just over half of the samples contained evidence of an actual louse infestation, and only half of those indicated a recent active infestation (live lice or viable nits). This was not a controlled study, but it does underscore the possibility of misdiagnosis.

This will come as no surprise to parents who have looked for nits and lice for the first time and are astounded at the number of things in their child's hair. Dawn Mucci, of the Toronto-based Lice Squad, says, "Lots of things get mistaken for nits - dandruff and other debris, even sand and art supplies."

Nits can go undetected as well. In a Belgian study that compared traditional scalp inspection to wet combing (using a conditioner, a magnifying glass and a fine-tooth comb), 30 percent of the children who were identified as having nits from a scalp inspection actually didn't have them, and 10 percent of those found not to have nits, actually did. The study concluded that wet combing was the more accurate diagnostic method.

What we know
Nits and, to a lesser extent, lice are harder to identify than people think.

Bottom line
If you're not completely sure, get a second opinion and ask to have your child assessed with the wet-combing method. Don't use lice shampoo unless you're certain your child has lice.


What we've heard
This is one of the biggest fights of all. Should children be required to be nit-free before they return to school? Pollack says he has yet to see a shred of evidence that no-nit policies have any appreciable effect on the incidence or prevalence of lice. "In my experience, these policies are unjustified, misapplied and cause much greater harm than the lice themselves. Head lice are merely a nuisance. The no-nit policies deprive kids of educational opportunity and are a financial burden to the parents."

Karen Tilley, president of a Canadian company called LiceBusters, scoffs at this: "You'll notice that the people who are saying lice are just a nuisance aren't the people who are dealing with them," says the former Toronto resident, whose company operates a toll-free lice information service, sells lice removal kits and counsels people to stop using louse pesticides. "It seems to me that the removal of no-nit policies is a good way to ensure that people keep buying the pediculicide shampoos, which often don't work very well to begin with."

Altschuler's position is that getting nits out is a key aspect of head lice control. "We don't really like the term no-nit policy," she says. "This isn't really about excluding children from school. It's about setting a standard that puts education first, before outbreaks, and encourages frequent screening. If most families use this approach, then the system can be there to assist the kids whose parents don't have the resources to do it."

What we know
Not all nits will produce lice - some are "dead" and some are already hatched. The question is: Can you tell the difference? It only takes a few viable nits to keep the cycle alive. As for no-nit policies, they probably would help reduce the spread of lice if they were supported by competent diagnosis (which appears not to be the case) and treatment.

Bottom line
Removing as many nits as possible seems like the one way to ensure lice and all their potential progeny are gone. Proper equipment is important.


Here's what to do if you get that dreaded note from school:

Make sure it's really lice. Ask an experienced lice checker to go over your child's wet head with a lice comb.

If you decide to use a lice shampoo, follow the directions carefully (including the second treatment). Don't leave the product on longer than indicated and don't use it over and over and over. Finally, use the shampoo with the understanding that there's a significant chance that it might not kill all the lice. Herculean efforts to eliminate lice from clothing, bedding and furniture (apart from normal washing and vacuuming) are most likely a waste of time, since lice can't live for more than 24 hours without a blood meal and can't jump or fly.

Get the lice and nits out by hand. "Until you manually remove these things, they're going to stay in your hair," says Deborah Altschuler. "This approach is less noxious than repeated chemical treatments and, if done properly, more likely to be successful."

The best tool, according to Altschuler is the LiceMeister, a nit comb which originated in Germany. "We were skeptical at first. We've had so many products sent to us," she says. "But when we finally got around to trying it, we were blown away with what the comb pulled out." What it didn't pull out was hair. The comb is made from highly polished stainless steel; it has longer, more tightly spaced teeth and goes through more hair with each pass.

If picking out nits and lice by hand sounds like too much work - it can easily take an hour or more every day - some parents now have the option of hiring someone to do the job. The two most prominent Canadian nitpickers are Karen Tilley and Dawn Mucci. Tilley began by treating a friend and before long was helping three or more families a week. Mucci has now taken over the in-home part of the business, called the LiceSquad. If you live close to Toronto, Mucci or one of her associates will come to your home and treat your family for $55 an hour, plus travel. Tilley now concentrates on her toll-free lice information line and the marketing of her kits (which start at $55). The most popular one sells for $135 and includes Tilley's own essential-oil-based lice treatment, a magnifying visor, a booklet and the LiceMeister.

If lice outbreaks are chronic in your child's classroom, screen your own child regularly every week. This may help you catch an infestation before it gets out of control.


Lice are greyish-brown crawling insects (about the size of a sesame seed) that feed on human blood. They live for up to 30 days on the human head and are usually found around the nape of the neck or behind the ears. They don't live on pets and they can't survive off a host for more than about 24 hours. Louse eggs (nits) are tiny and pearl coloured. They stick to the hair shaft with a glue-like substance and take about eight days to hatch. Lice reach sexual maturity nine to 12 days after hatching; they can lay up to six eggs per day and about 100 in total.

Originally published in Today's Parent , April 2002



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