A Lousy, Nit-Picking Epidemic

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Researchers speculate that overexposure to permethrin may have sparked a process of natural selection in lice. A similar use of preventive insecticides encouraged the rise of resistant strains of the mosquitoes and black flies responsible for transmitting malaria and African river blindness. Although no definitive studies on resistant strains of head lice have been completed in the U.S. (results of a Harvard investigation won't be ready for several months), two recent papers from Israel and the Czech Republic seem to support the resistant-strain theory. Says Thomas Bell, health officer for three counties in Washington State: "How do you induce resistance among a population of insects, bacteria or whatever? You expose the population to a sublethal dose of the chemical you're trying to kill them with, and that way you select for the strongest."

Even though the theory remains to be proved, its implications dovetail with the experiences of parents like Michele Colburn, a working mother from Washington who recently spent six months battling lice on her 11-year-old daughter. "The lice would disappear from her head and then reappear," Colburn recalls. "I went to the public library at the National Institutes of Health and read up everything on lice. I borrowed a magnifying glass that is used in the museum for conservation work so that I could check her head for lice. I tried every shampoo on the market. I bagged all her toys. I washed 20 loads of laundry every week. But they would just keep coming back." Says Kramer, the medical entomologist: "It's so frustrating for so many people. We can't really recommend products that are 100% effective."

As a result, parents have been turning to all sorts of bizarre alternatives, including eucalyptus and neem oils and chrysanthemum-flower extract, solutions that have been recommended on the Internet. Others have taken to smearing their children's heads with mayonnaise, petroleum jelly or Crisco, then having the kids sleep in a shower cap. In July a 13-year-old girl in Lorimor, Iowa, died after her mother doused her head in gasoline and a pilot light on the family's hot-water heater ignited the fumes. Last spring, a six-year-old Oklahoma girl stopped breathing temporarily after her mother's boyfriend soaked her hair in Diazinon, an agricultural insecticide. "It's a commentary on how bad the situation is," says Kramer. "Physicians are running out of things to tell people to use."

And what do the experts recommend? The key is removal of the nits, which are much harder to spot than the full-grown lice and which only lead to more of the insects if they are not painstakingly picked or combed out during thorough examinations of a child's hair. Some kids may benefit from a number of over-the-counter products, but their efficacy varies from case to case. For nit and lice removal, several school systems are experimenting with a metal-toothed comb endorsed by the nonprofit National Pediculosis Association (www. headlice.org) Advice on insecticides and home remedies, as well as on the best methods for cleaning sheets, clothing and pillowcases, is reviewed in two new books, Wiping Out Head Lice by Nicholas Bakalar (Signet; $5.99) and The Lice-Buster Book: What to Do When Your Child Comes Home with Head Lice by Lennie Copeland (Warner Books; $8.99).