Super Head Lice

       When I last wrote about head lice in March, 2012, medications that could be purchased over the counter were still effective in treating head lice.  That is no longer true.  The two medications that can be purchased without a prescription, permethrin and pyrethrin, are no longer effective according to an article published in the Journal of Medical Entomology.  The article states that 99.6% of head lice have a gene mutation that gives them immunity to these commonly used medications. Many head lice are also resistant to two other commonly used prescription medications, lindane and malathion.

     There are three new medications that are available by prescription and are effective in treating head lice. Benzyl alcohol comes in a lotion that is applied for 10 minutes to the hair and scalp and then rinsed off and repeated in a week. (“nits” – the lice eggs - hatch in a week). Spinosad is a lotion that is used in the same way.  Both can cause irritation to the scalp. Ivermectin is available in both a hair/scalp preparation and as an oral medication. Ivermectin kills both lice and eggs, so no repeat dose is necessary. Sulfa-based antibiotics are also used to treat head lice, but they can cause serious allergic reactions.

     Wet combing – using a fine-toothed nit comb after lubricating the hair with a substance to make the comb pass more easily – is now considered the best way to make the diagnosis of head lice. If live lice are obtained by passing the wet comb through the hair., the child has an infestation. However, if a parent sees the child itching the scalp and then notices nits or lice on the hair, the child almost certainly needs treatment. However, simple inspection is not adequate to tell whether a child has been treated successfully. It is thought that after treatment, 28% of children still have lice on their hair and 63% still have nits. This is important because schools bar children with lice from coming to school and many schools have a “no-nit “ policy for allowing the child to return to school – if the nurse sees a nit, the child goes home. This results in millions of needlessly lost school days every year.

     Repeated wet combing is also used as a treatment for head lice for people who don’t want to use medications. The lubricated hair is combed for up to 30 minutes every 3 to 4 days until no live lice are found and then continued for about 2 weeks after that to ensure successful treatment.

     There are many other treatments commonly recommended but without any real scientific proof of effectiveness. Smearing olive oil, petroleum jelly or mayonnaise in the hair doesn’t really “suffocate” the lice. Heat applied through an electric comb or a hair drier doesn’t work, either.

     Finally, many of the recommendations about how to clean the house when a child has lice are part of the general overreaction that we all have as parents when we think of bugs crawling on our child’s head. Lice that fall off the head probably don’t live more than 48 hours and any head louse that would crawl off a nice, warm, bloody scalp in order to attach to a stuffed animal probably wasn’t going to live long anyway. It is reasonable to hot-water wash hats and linen that were used for two days before the diagnosis was made, but putting all the stuffed animals in a bag for two weeks or spraying the furniture with anti-lice spray aren’t necessary. Also, don’t blame the family dog or cat – they don’t carry human lice.