Bollettino epidemiologico nazionale

Pediculosis

Editorial Committee, BEN, with the assistance of Marta Ciofi degli Atti, Alberto Tozzi, Cristina Rota, of the Laboratory of Epidemiology and Biostatistics at the Istutito Superiore di Sanità and Luisella Grandori of the Local Health Authority of Modena.

In Italy, an increase has occurred in the number of cases of pediculosis (Pediuculus capitis), which occur primarily in school-based outbreaks. The number of reported cases, which undoubtedly represents an underestimate, rose from 3449 in 1990 to 4907 (in 1009 different outbreaks) in 1999.

Pediculosis is caused by a tiny louse (2-3 mm in length) that lives exclusively in the scalp of humans. Lice feed on human blood, and each day the females lay 8-10 eggs, which are firmly fixed to the hair shaft with a collagenous substance. The eggs hatch after approximately 20 days. Lice can survive only one or two days outside the scalp.

Pediculosis is not a sign of poor hygiene and affects persons of all social strata.  Spread occurs through person-to-person contact, or less easily, though contact with fomites such as combs and brushes, hats, and bed linen. As a result, spread within the family and within classrooms is extremely common.

Although many public health staff regard pediculosis as a problem of minor public health importance, it generates considerable concern on the part of parents and frequently leads to actions that are unwarranted or potentially harmful. Prevention and control of pediculosis requires the involvement and cooperation of public health, schools, and families.

Public health personnel can play an active role in providing training to school staff in the recognition of the problem and providing posters or distributing materials that can be distributed to families regarding recognition and treatment. In fact, one of the most frequent causes of ongoing transmission appears to be the failure of families to recognize the egg casings.

In addition, the public health authorities may need to intervene in the case of ongoing or extensive outbreaks in school settings or in settings where anxiety levels are high. In these situations, the community pediatricians or other public health personnel can work with school authorities to perform a rapid assessment of the extent of the problem, organize mass treatment if warranted, ensure certification for school re-entry, and  provide ongoing surveillance to assess whether the problem has been resolved.

In most situations, however, the intervention of public health staff is unnecessary. Schools that have been provided with adequate information on recognition and management of pediculosis can handle the problem without external intervention. Specifically, they can notify other parents of the need to when one or more cases are detected in class members and assist in organizing mass treatment if multiple class members are affected or the outbreak is prolonged.

Finally, the family plays perhaps the most essential role in control of pediculosis in school settings through ongoing surveillance for the presence of lice and their eggs, and in the prompt provision of treatment. A simple way of ensuring ongoing inspection is to urge parents to wash their children’s hair twice weekly with regular shampoo and check their heads at that time.

When a child is found to have an infestation, treatment of the affected child should be initiated and other family members should be inspected for the presence of the parasite and treated as necessary. The most effective products to eliminate lice are shampoos, lotions, and gels  based on pyrethrin, piperonibutiside, pyrethroids, permethrin, or other anti-parasitics, which are normally sold in pharmacies. In some situations, greater efficacy is achieved when a second application is made 7-10 days later. Combs and brushes should be cleaned with hot water and should be soaked in a basin containing solution of anti-lice shampoo. In addition, sheets, pillows, towels and other items that may have come in contact with the lice or their eggs should be washed in the washing machine on a 60 degree cycle. With regard to the household or classroom, normal cleaning is adequate. It is not necessary and may even be harmful to use insecticides in an attempt to eliminate the parasites. After treatment, a fine-tooth comb should be used to remove the egg casings.  Cutting hair and using anti-lice shampoos are not effective as preventive measures.

For additional information:

1) American Academy of Pediatrics: Red Book (Report of the Committee on Infectious Diseases),  25° ed. Elk Grove  Village 2000

2) A.S. Benenson: Manuale per il controllo delle malattie trasmissibili. DEA ed., 1997

3) C.M. Mazurek, N.P. Lee: How to manage head lice. West J Med 2000, 172:342-345

4) Bartolozzi G. I pidocchi del capo. www.medicobambino.com/