Head lice are not your typical pests. For one thing, they largely afflict children. For another, they have very short lives off their host, so are not considered structural pests. Yet PMPs and school IPM coordinators are frequently asked questions or asked to help with head louse infestations. So I think it's important for the pest control community to know something about these insects, and the latest treatment options.
With the new school year, we expect new cases of head lice. And according to a new paper delivered at the American Chemical Society and reported this week in Smithsonian.com, this year's head lice are running with a tougher crowd. In the paper by Kyong Sup Yoon, Southern Illinois University-Edwardsville, Texas is among 25 states tested so far and shown to have head louse populations that are resistant to the most commonly used over-the-counter (OTC) head louse shampoo treatments: pyrethrins and permethrin. In fact, most of the samples tested by Yoon and colleagues (104 out of 109 samples) showed resistance to OTC louse treatments.
If you work with school nurses at a school district, or are asked by customers about lice treatment, or are simply a parent yourself, it pays to be familiar with the latest treatment options for head lice. After all, these aren't your mother's lice.
First, many lice problems can still be handled with OTC products. Keeping IPM in mind, however, multiple methods (insecticide plus mechanical control in this instance) are always better than one. Louse combs are a great second tool in the parents' tool box. These fine toothed combs allow hair to pass between the tines, but not lice. Combing should always be done in combination with use of a louse shampoo.
Sklice®), spinosad (Natroba™), and benzyl alcohol (Ulesfia®). These products will likely be more expensive, you you might want to try the OTC route + combing first. But it's always good to have options. A recent review article by Drs. Cynthia Devore and Gordon Schutze in the journal Pediatrics does a nice job of reviewing these as well as other options for treating children for head lice.
Devore and Gordon also address the current recommendations for how schools should handle control including whether children should be screened, how to manage a child on the day lice are detected, and whether children should be restricted from school (they argue no). This paper could be an especially useful resource pass on to your school nurse if you work for a school district.
To spray or not to spray
So are environmental sprays needed to help control head lice infestations in a school or home? One can certainly find pesticides labeled for environmental louse control. Most professionals say no, sprays are not necessary.
Transfer of lice on furniture from one person to another can certainly occur. I remember a day when my daughter had head lice. She was reading a book in our living room chair when she got up to go outside. I started to take her place when I noticed a live and hungry-looking head louse on the chair back where her head had been pressed.
Despite the occasional transfer of lice via furniture or bedding in this way, spraying of such items is not recommended. Head to head contact, sharing of combs, scarves and hats during play, are far more important means of transmission; and spraying will not help stop these activities. Simple washing of hats, pillowcases and clothing is a safer and more effective means of dis-infesting these items than pesticide sprays.
Keep in mind that these tiny insects have a very short life span once they are off the human head. Head lice are highly sensitive to desiccation, and according to the CDC live no more than 1-2 days off of a host. Any head lice lurking on a bean bag chairs or coat rack in a classroom, therefore, will not survive a weekend in an empty classroom.
So let's leave treatment of head lice to doctors and parents. But let's be ready to offer advice and provide resources for customers and colleagues battling these adaptable pests. For more information on head lice see our Extension publication on head lice.