Understanding Scabies and Lice

Incidence and Health Risks

Scabies and lice have no geographic boundaries nor do they discriminate by age, race, gender, or social class. Each affects millions of Americans and hundreds of millions of people worldwide. The incidence of these infectious conditions has increased steadily in recent decades, despite available treatments.1,2 If left undiagnosed. or poorly managed, scabies and lice can lead to more significant health risks and increased public health burden.

Scabies and lice are diseases of global proportion

Anyone can get scabies:

Over 300 million people are affected by scabies worldwide, with millions of infections in the U.S. alone3
People of all ages, genders, races, and social classes get scabies4
Scabies is easily spread within families, to sexual partners, and among people living in crowded conditions5

Some people are at greater risk for scabies:

Hospitals, nursing homes, and long-term care facilities are likely sites of scabies epidemics5
People with weakened immune systems, such as those with HIV/AIDS, and the elderly are at risk for Norwegian (crusted) scabies, a more severe form of the disease6

: Poor hygiene is not thought to be a factor in the spread of scabies7

The incidence of lice infestation has increased over the last three decades:2

An estimated 10–12 million Americans are infested with lice each year2,8
Worldwide, hundreds of millions of cases of lice are reported annually2

Image of head lice infestation showing hair strands covered in “nits” or eggs. Severe itching and scratching can lead to bacterial infection and clumping of hair from fluid that weeps from the infected area.

Head lice and pubic (crab) lice are the most common forms in the U.S.:

Head lice are most often diagnosed in school-aged children 3 to 11 years old due to the close quarters of classrooms and daycare facilities2
Pubic (crab) lice are a common finding among sexually active people between the ages of 14 and 402,4

: Estimates of the incidence of lice infestation are likely low due to social stigma, self-treatment, and underreporting2,9

Scabies and lice can lead to other medical complications

Scabies complications can be serious:

Severe bacterial infection of the skin5
Bacterial infection of the blood (known as sepsis)5
Infection of the kidneys (glomerulonephritis)7
Progression to crusted or Norwegian scabies—an advanced, potentially life-threatening form of the disease*5,10

* Please note that lindane is contraindicated for the treatment of crusted (Norwegian) scabies and should not be used for this condition.

Heavy lice infestation of the scalp with secondary abscess formation

Bite reactions and secondary infections can complicate lice infestations

Bacterial and fungal infections, characterized by a foul-smelling matted clumping of hair, lice, and nits2,11
Pustules, crusting, and adenopathy (glandular infection)2,12

References:

Roos TC, Alam M, Roos S, et al. Pharmacotherapy of ectoparasitic infections. Drugs. 2001;61(8):1067–1088.
Guenther L, Maguiness S, Austin TW. Pediculosis. 2005. Available at: http://www.emedicine.com/med/topic1769.htm.
Chosidow O. Scabies and pediculosis. Lancet. 2000;355:819–826.
Orion E, Matz H, Wolf R. Ectoparasitic sexually transmitted diseases: scabies and pediculosis. Clin Dermatol. 2004;22(6):513–519.
Wendel K, Rompalo A. Scabies and pediculosis pubis: an update of treatment regimens and general review. Clin Infect Dis. 2002;35:S146–S151.
U.S. Centers for Disease Control and Prevention (CDC). Parasitic Disease Information: Scabies Fact Sheet. 2005. Available at: http://www.cdc.gov/ncidod/dpd/parasites/scabies/factsht_scabies.htm.
McCarthy JS, Kemp DJ, Walton SF, et al. Scabies: more than just an irritation. Postgrad Med J. 2004;80:382–387.
West DP. Head lice treatment costs and the impact on managed care. Am J Manag Care. 2004;10(9 Suppl):S277–282.
Hansen RC. Overview: the state of head lice management and control. Am J Manag Care. 2004;10(9 Suppl):S260–S263.
Walton SF, McBroom J, Mathews JD, et al. Crusted scabies: a molecular analysis of Sarcoptes scabiei variety hominis populations from patients with repeated infestations. Clin Infect Dis. 1999;29:1226–1230.
Wiederkehr M, Schwartz RA. Lice, scabies, and bedbugs. Best Practice of Medicine. October 2003. http://merck.micromedex.com/index.asp?page=bpm_report&article_id=BPM01DE11&section=report.
Habif TP. Pediculosis. In: Clinical Dermatology, 4th edition. New York: Mosby; 2004:506–510.