In many parts of the US, teachers in nursery, kindergarten and elementary school classes regularly check the heads of pupils for head lice and nits (eggs) and send them home immediately if they find any.
Head lice that infest between six and 12 million children’s heads each year in the US alone and countless millions more worldwide. The lice have evolved into pesticide-resistant parasites that are more difficult to eliminate from children’s scalps than 40 or 50 years ago.
This hardy strain of bugs has led to the creation of a new industry: professional delousing consultants (nit-pickers) who come to your home for a few hundred dollars and comb and pluck away every last louse and egg. Professional lice removal is already a billion-dollar industry in the US. But that doesn’t mean that the practitioners know what they’re doing.
The negative view of head lice comes from the incorrect view that the parasites prefer “dirty” heads of children who have poor hygiene, but in fact, many infestations occur in upper-class children who are “clean” and have a healthy, hygienic environment.
Prof. Kosta Mumcuoglu, Israel’s top parasitology expert on head lice, recently headed an international team that wrote an article in the International Society of Dermatology about misconceptions on pediculosis. They argue, among other things, that a “no-nit” policy in educational institutions is “unjust and is based on misinformation rather than on objective science and should be discontinued.”
The team included experts not only from Mumcuoglu’s department of
microbiology and molecular genetics at the Hebrew University-Hadassah Medical in Jerusalem, but also from Harvard University;the University of Florida; the University of Queensland in Brisbane, Australia; Florida Atlantic University in Boca Raton; the Center of Insect Infections in Buenos Aires, Argentina; Hitit University in Turkey; Near-East University in Cyprus; the Henri Mondor Hospital in Paris; the German Environment Agency in Berlin, the ommunity Hygiene Concern in the UK; the Global Health Association of Miami; and Ghent University in Belgium.
“Head-louse infestations continue to be a concern of public health in most countries, including the most developed ones,” they wrote. “[Our] recommendations are intended to inform and stress the role and impact of the different authorities, institutions, industry and the public in the control of head lice to reduce the prevalence of this parasite. We encourage health authorities to pursue more effective methods to correctly identify such infestations and evaluate existing and new pediculicides, medical devices, louse repellents and louse- and nit-removal remedies.” A placebo-controlled clinical trial demonstrated the efficacy of a citronella formulation as a louse repellent when applied topically on the head of children.
The team added that medications and medical devices aimed at eliminating head lice must have verifiable claims in the instructions for use and should be tested periodically to document current levels of resistance by lice to the active ingredients and to the formulated products. “Where the prevalence of lice is claimed to be epidemic, children should be periodically evaluated objectively to document the actual level of prevalence. Continuing education for health providers and the general population promises to correct misinformation regarding the biology, prevention, and management of lice. Parents should
regularly inspect their children for head lice and treat as necessary.”
In addition, health authorities in the various countries should eliminate policies and practices that rely upon school exclusion as a means to reduce incidence and prevalence, sycg as the ‘no-nit’ policy that lacks scientific justification, and are counterproductive to the health and welfare of children.
The head louse, known as pediculus humanus, lives on the scalp of human beings, where it feeds exclusively on blood. Infestions occur mostly in children because they learn and play with their heads close together, but they do not develop serious symptoms, wrote Mumcuoglu and colleagues. Itching of the scalp can result in loss of sleep or concentration at work or school and excessive scratching occasionally poses risk of secondary skin infections. For many, head lice – or the fear of exposure to these pests is more an emotional and psychological problem rather than a clinical one. “Head lice become a public health concern when their prevalence increases and when perspectives, policies, and practices to prevent and abate these pests pose even greater risks to people than the infestation itself,” they wrote.
Increased prevalence of head louse infestation has been reported from Israel, Denmark, Sweden, UK, France, US, Iran, and Australia. Head lice normally move to a new host when an infested person’s hair is in direct contact with that of another person. Social and familial contact between children, as well as between parents and children, are more likely routes of infestation than via shared combs, brushes, towels, clothing and linens. Because of their longer hair, girls are diagnosed as infested two to 10 times more often than boys, and children between age four and13 years are most frequently affected. “Only evidence-based effective products that are not harmful to children or the environment should come to market. Introducing a new pediculicide into the market can only be based on a thorough evaluation of the formulation’s safety and efficacy. Pediculicide with an active ingredient that is already well-established for use in the marketplace but offered for registration in different concentrations, combined with different chemicals, or proposed in different dosages, may provide markedly different results. Therefore, each formulation should be tested separately in well-designed studies,” they continued.All new products whether they rely upon new chemistries, active ingredients currently approved but in products that differ markedly in their formulation or use or on alternative modes of action should first be tested in the laboratory on colonies of body lice or on ex vivo lice samples; however, it should be noted that even ex vivo [experimentation or measurements done in or on tissue from an organism in an external environment with minimal alteration of natural conditions] tests are only an indicator of possible efficacy and should not be relied upon as a guide to effectiveness in clinical use, the team wrote.
Muculoglu wrote that plant extract remedies and anti-louse devices such as those relying upon heated air, suction or “electronic teeth” must also
be evaluated before their introduction to the market. Because it is less likely that lice will develop resistance to mechanical methods, nonchemical products might not need periodic evaluation.
“Advertising for any product should prominently display whether it is licensed, either as a pharmaceutical product or a medical device.” Health providers such as physicians, nurses, and pharmacists should be well-informed about effective anti-louse strategies and products and updated on new developments. School nurses should address the head louse problem proactively by making information available to parents and investigating institutions with a high level of complaints. In addition, the school nurse can support families who find it difficult to manage treatment. Pharmacists should promote pediculicides only if health authorities have found them effective.
Mumcuoglu, who has examined the heads of endless young children to determine efficacy of various medications and devices (and often unwittingly taken his “work” home), said that studies involving 15,000 children in Israel using a louse comb revealed that 11% to 19% of the children were infested with living lice and eggs, while another 22–30% had nits only. About 80% of the children with signs of previous infestations had nits that were two to five centimeters away from the scalp, which was evidence of successfully treated infestations during the previous two to five months. So “when the diagnosis of head louse infestation is based solely on the presence of nits, one to two out of three were mischaracterized as being infested and could be sent home for treatment without justification.”
The team recommended that children with lice should be sent home only at the end of the school day with a letter to their parents suggesting that the child be examined and, if necessary, treated on the same day. “Excluding children from school because of the presence of lice or nits is discouraged because the infestation is likely to have been present for several days or even weeks. Parents should be given a pamphlet offering an informed choice of treatment methods and notification
of whom to ask if there are questions about which medications or other treatment methods would give the best results. Children should be allowed to return to school the next day, they stressed. Ideally, the school nurse could check for lice in her office upon return and again on the 10th day after the letter was sent and do follow-up inspections until the treatment is successful.