Head lice infestations, a perennial nuisance for parents of school-aged children, are becoming increasingly difficult to treat as the insects develop resistance to common insecticides. This trend is particularly concerning as millions of children return to classrooms after summer holidays, a period when head lice often spread rapidly. Sales of head lice treatments saw a significant jump of 57 percent in September last year, according to one online pharmacy.
Experts are warning that decades of exposure to insecticides like permethrin and malathion have led to the evolution of so-called "super lice" that can survive treatments that were once effective. The National Health Service (NHS) in the UK now advises against products containing permethrin due to their reduced efficacy.
Understanding Head Lice Transmission and Identification
Head lice are tiny, blood-sucking insects that live in human hair and on the scalp, feeding and laying eggs. Contrary to popular belief, they cannot fly or jump but crawl from one person's head to another through close head-to-head contact, which can occur in as little as 30 seconds. Children commonly contract lice from friends and siblings during play, in schoolyards, parks, or social gatherings. While infestations often become noticeable in September, children may have picked them up during the summer holidays, as it can take several weeks for an infestation to become apparent and for itching to begin.
While it is possible for lice to spread through shared items like hats or brushes, experts state this is far less common because lice are adapted to living on the human scalp and do not survive long when separated from it. Head lice have no preference for clean or dirty hair; the idea that they are a sign of poor hygiene is a myth.
The definitive sign of head lice is finding a live, moving louse. Adult lice are about the size of a sesame seed and range in color from greyish-white to brown. Their eggs, which are much smaller, are firmly glued to hair strands close to the scalp, particularly behind the ears and at the nape of the neck. Unlike dandruff, lice eggs are difficult to remove. Itching, a tickling or crawling sensation, and scratching that leads to red bumps are common symptoms, but some individuals may experience little or no itching.
Treatment Strategies
When treating head lice, experts recommend carefully selecting products. Treatments generally fall into two categories: traditional insecticides that poison lice, and newer "physical" treatments, often containing silicone-based substances like dimeticone, which physically suffocate or dehydrate the insects. Hedrin 4% Lotion, containing dimeticone, is one such pesticide-free option that requires application to dry hair for eight hours or overnight before washing out.
Regardless of the product used, repeating treatment is crucial. Experts advise repeating the treatment after a week and continuing to check for live lice for the following week to 10 days, as some eggs may survive the initial application and hatch later.
The Effectiveness of Wet-Combing
Despite the availability of various treatments, many experts consider wet-combing to be one of the most effective methods for eliminating head lice, as insects cannot develop resistance to physical removal. This method involves applying conditioner to wet hair and systematically combing through sections with a fine-toothed detection comb from root to tip. After each stroke, the comb should be wiped clean or rinsed to check for lice. Research suggests that systematic wet-combing can be more successful than some chemical treatments.
The NHS recommends a schedule of wet-combing on days one, five, nine, and 13, with a final check on day 17 to ensure the infestation is clear. Using a comb with teeth spaced no more than 0.3mm apart is recommended to catch even tiny newly hatched lice. It is also important to check and treat all household members found to have live lice simultaneously to prevent re-infestation.
Debunking Myths and Prevention
Contrary to some concerns, there is no need for extensive household cleaning, such as stripping beds or freezing soft toys. Head lice are highly adapted to living on the human scalp and typically die within 8 to 12 hours when separated from their host. Since lice spread primarily through direct head-to-head contact, a deep clean of the home is unlikely to significantly impact an infestation.
There is limited clinical evidence to support the effectiveness of preventive products like defence sprays or special shampoos. Experts suggest that avoiding head lice is difficult, as it is a natural part of social interaction. The NHS states that children with head lice do not need to be kept out of school. While tying back long hair may slightly reduce the chances of head-to-head contact, regular checks with a detection comb are considered a more practical approach for early detection and treatment.