Head Lice Grow Resistant to Treatments

Researchers Suggest End to No-Nit Policies in Schools

By Denise Mann
WebMD Health News

Reviewed By Louise Chang, MD

July 26, 2010 -- There is little else that triggers such a visceral reaction from parents than the words "head lice," especially when they are uttered in conjunction with an outbreak in their child's classroom or summer camp.

But when it comes to these creepy, crawly, head-dwelling creatures, there is nothing to fear except fear itself, say researchers in an updated report on the diagnosis and treatment of head lice in the August issue of journal of Pediatrics.

Yes, head lice are gross, but they are not a health hazard or a sign of poor hygiene. They don't spread any disease, and controversial no-nit policies, which state that if your child has any sign of lice or their eggs (nits) they should be kept home, should be abandoned, they say.

"It's only a bug on your child, not in your child like the flu or pneumonia," study author Barbara L. Frankowski, MD, MPH, professor of pediatrics at the University of Vermont in Burlington, says in an email. "Healthy children -- which includes children with head lice infestation -- should be in school learning."

Treatment-Resistant Head Lice

The new report was last updated in 2002, and since that time, there has been a growing concern that lice are becoming resistant to some common over-the-counter treatments such as permethrins (like Nix) and pyrethrins (like A-200, Clear Lice System, Pronto, R & C, and Rid).

"They are still a good first-line treatment for most since they have been proven to be so safe and are available over the counter, [but] if these products don't work and you are sure you have the correct diagnosis and have used the product properly, then you would want to talk to your health care provider about second-line prescription medications," Frankowski says.

Another option is wet combing with a fine-toothed lice comb to make the lice easier to catch and remove, or suffocation (petroleum jelly or another product is massaged into your child's hair, he or she wears a shower cap overnight and doesn't wash their hair until the morning).

"Wet combing and suffocation methods are more time consuming, but can be helpful for parents who wish to avoid chemicals," she says. "None of the methods are 100% effective, and often need to be repeated for two or three cycles," she says. This includes nonprescription products.

There are some newer treatments available that target lice that have developed resistance. "There are several prescription options like Ulesfia, Ovide, ivermectin, and your health care provider can help you weigh the risks and benefits for your child," she tells WebMD. While effective, these treatments may have some risks attached to them, and need to be studied for longer periods of time. Another prescription product used to treat lice is lindane shampoo (Kwell).

Diagnosing Head Lice Is Tricky

Diagnosis of head lice is not a slam dunk, and misdiagnosis of head lice may play a role in treatment resistance, says Cindy DeVore, MD, a pediatrician and school physician in New York State and the chair-elect for the Council on School Health of the American Academy of Pediatrics.

"Parents may misdiagnose head lice when they see flecks of dandruff or debris and mistake it for head lice in the face of a classroom parent notification of lice," she tells WebMD in an email. "Because self-treatment has been available, involvement of physicians in the care of a child with head lice tends not to occur, and overuse and misuse of OTC medicines likely have complicated sorting out what is actual resistance and what is simply inadequate, inappropriate, or under-treatment."

Treatment should only be started if there is a clear head lice diagnosis, she says.

Bernard Cohen, MD, chief of dermatology for Johns Hopkins Children's Center in Baltimore, agrees.

"Despite resistance to treatment, I think the most common cause of spread and treatment failure is failure to identify and effectively treat all infested kids."

Preventing Lice Not Easy Either

So if diagnosis is tricky, and lice are starting to outsmart some of the more common treatments, what about prevention?

Lice can't hop or fly. Instead, they crawl from head to head. "Totally preventing head lice is probably impossible, if you have a normally active, social child," Frankowski says. "Head lice is a normal risk of childhood, just like colds and scraped knees."

"Although most lice infestations are spread by direct head-to-head contact, many advise teaching children not to share combs and brushes," she says. That is OK, but "not using helmets for safety because you are afraid of lice is never an option," she says.

"Most cases of head lice are community acquired, often at sleepaway programs or parties, and not uncommonly in the summer," Devore says. "Parents should do regular surveillance of young children, checking the napes of necks, behind ears, and throughout the scalp, looking for signs of live lice or "nits" cemented to hair shafts close to the scalp that are not readily pulled out," she says.

And "if there is a significant outbreak in a classroom of more than 20% of the children, the parent can check with the primary care physician to see whether use of a permethrin rinse on an uninfested child might confer some protection until the infestation in the classroom calms," she says.

Not All In Favor of No-Nit Policies

Although the researchers do stress abandoning no-nit policies to avoid prolonged, unnecessary absences from school, other organizations, including the National Pediculosis Association, still support them. The nonprofit group states that not removing nits is the main reason treatments don't work, and if children with hatching nits are readmitted to school, the head lice outbreak will continue.

"While absence from school or child care is a loss of educational opportunity and an encumbrance to working parents, readmitting an infested child is not the solution," the group states. "A policy for head lice must consider not only the infested child, but also his or her peers who have already been successfully deloused or who have not yet been infested."

SOURCES: Frankowski, B. Pediatrics, July 2010; vol 126: pp 392-403.

Bernard Cohen, MD, chief, dermatology, Johns Hopkins Children's Center, Baltimore.

Barbara L. Frankowski, MD, MPH, professor of pediatrics, University of Vermont, Burlington.

Cindy Devore, MD, pediatrician, chair-elect, Council on School Health, American Academy of Pediatrics.

National Pediculosis Association.

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