Overview: the state of head lice management and control.

Head lice infestations affect millions of people in the United States. Children become infested more often than adults and account for the largest percentage of infestations. Head lice have not been shown to transfer disease, and they are not associated with serious morbidity. The most common effect of lice infestation is pruritus of the scalp with occasional cutaneous infection caused by scratching. Nevertheless, many schools have "no-nit" policies, which require the dismissal of children from school if nits or lice are found. These policies are ineffective in preventing infestations and result in many missed days of school. Lice infestations are most effectively managed with pediculicides. Pyrethroids are the mainstay of over-the-counter products. Prescription pediculicides include OVIDE (malathion) Lotion, 0.5% and lindane (formerly marketed as Kwell). Resistance to pyrethroids due to misuse and overuse has been documented. Lindane resistance also has been reported, and serious safety issues about lindane have been raised by the Food and Drug Administration. Lindane labeling now includes warnings and several restrictions in its use. Malathion is not associated with major systemic safety issues or the development of resistance within the United States. A contributor to pediculicide resistance is misdiagnosis of lice infestations. Survey data reveal frequent misdiagnosis of infestations in children who do not have live lice. Physicians generally are more likely to misdiagnose infestations than nonhealthcare providers. Misdiagnosis contributes to resistance by causing overuse, and consequently overexposure, of pediculicides. These agents should be used only if live lice or viable nits are discovered. Head lice infestations generally do not contribute to health risks for individuals or the public. The most serious consequence is the social cost of missed school days and the associated cost of lost productivity and wages of parents who must care for children sent home from school. Better diagnosis, more appropriate use of pediculicides, and elimination of no-nit policies will improve the overall management of head lice infestations.