There is nothing “super” about head lice. The so-called “super” lice are populations of lice that have evolved resistance to the insecticide permethrin. For years, permethrin has been the top selling Over-The-Counter insecticide for elimination of lice.
However, overuse of permethrin has led to resistance. Permethrin kills lice by interacting with proteins in the nerve axons of insects to disrupt nerve conduction. Some lice have mutant proteins and are not killed by permethrin. These resistant “super” lice survive and pass their genes for resistant proteins to the next generation, while susceptible lice are killed and their genes eliminated from the population. Over time, the lice population will have very few individuals that can be killed by permethrin and many that can not be killed. For such populations, permethrin no longer works.
What to do with super lice? The permethrin resistant lice must be treated with other products. Those products may be more difficult to use or require a doctor’s prescription making them more expensive. “Super” lice populations can increase in the human population because 1) people treat the lice with ineffective permethrin and the lice are not eliminated. 2) people don’t treat for lice because they can’t afford the prescription cost. 3) people use a product that is less effective or they use it less effectively because it is more difficult to use. All these factors can increase the prevalence of lice in the population and increase the risk of an individual getting lice. It is important that communities, doctors and public health programs intervene when super lice start to increase.