Introduction
Background
Louse infestation remains a major problem throughout the world.1 Head louse infestation among school children has reached epidemic proportions in many parts of the United States. Body lice are important vectors of disease. This article discusses pediculosis capitis (head lice), pediculosis corporis (body lice), and pediculosis pubis (pubic lice, crabs). All medical information must be interpreted in the context of the patient and the clinical situation. This article provides general medical information; it is not intended to be a guide for the treatment of any specific patient.
The head louse, Pediculus humanus capitis, has an elongated body and narrow anterior mouthparts. Body lice look similar but lay their eggs (nits) on clothing fibers instead of hair fibers.
The pubic louse, Pthirus pubis, is identified by its wide crablike body.
Pathophysiology
Louse infestation is prevalent throughout the animal kingdom. Mallophaga, or chewing lice, are common pests of birds and domestic animals. Humans sometimes are affected as accidental hosts. All 3 types of human lice belong to the order Anoplura, the sucking lice. Body lice infest clothing, laying their eggs on fibers in the fabric seams. Head and pubic lice infest hair, laying their eggs at the base of hair fibers.2,3 All 3 types take periodic blood meals by piercing the skin of their host with narrow anterior mouthparts. The 3 types of human lice are Pediculus humanus capitis (head louse), Pediculus humanus corporis (body louse), and Pthirus pubis (crab louse).
Evidence exists to show that infectious organisms are altered by their arthropod vector and that disease manifestations may be vector specific. For example, bartonellosis spread by a louse has different manifestations from bartonellosis spread by a flea or biting fly. This may explain, in part, the varying syndromes caused by closely related species of Bartonella organisms (eg, acute Oroya fever, Peruvian bacillary angiomatosis, bacillary angiomatosis of AIDS, bacillary peliosis hepatis, catscratch disease, infective endocarditis).4
Frequency
United States
Head louse infestation is a major problem, especially in urban areas. Major infestations are seen in all socioeconomic groups. The social stigma attached to louse infestation facilitates the spread of infestation. Families who are affected by such an infestation are reluctant to share information with their neighbors. Individual children are treated, but the community fails to address the infestation as a community-wide issue. School-wide and community-wide programs to eradicate lice are necessary to halt their continued spread.
In the United States, pubic lice generally are spread as a sexually transmitted disease (STD). Pubic louse infestation serves as a marker for other STDs, which may have been acquired simultaneously. Body louse infestation in the United States mainly affects the homeless. Body lice are vectors for Bartonella quintana, an agent of infective endocarditis among the homeless and the cause of many thousands of cases of trench fever and epidemic typhus during World War I.5 The organism that caused trench fever persists among the homeless in urban areas, spread from person to person by lice. Human reservoirs of typhus also exist in the population. Following natural disasters, body lice have the potential to spread rapidly throughout the population, causing great epidemics similar to those seen during World War I.
International
Head lice are a major problem throughout the world. Black populations appear somewhat resistant to P humanus capitis infestation, although they may develop scalp infestation by P pubis. The patterns of pubic and body louse infestation throughout the world mimic those in US refugee populations, which commonly have a tremendously high rate of louse infestation. Louse-borne disease is a potential problem whenever body lice spread through a population.
Mortality/Morbidity
Morbidity results from the severe itching that is caused by lice infestation. Mortality may occur from infectious diseases transmitted by the body louse.
Race
Blacks have a lower incidence of infestation by the head louse but may experience scalp infestation by P pubis.
Sex
Males and females are equally at risk for lice infestation.
Age
Lice affect all age groups. Body lice are indiscriminate in regard to the age of their host. Head lice are common in young school children but much less common after puberty. Pubic lice infest body and pubic hair. Prepubescent scalp infestation by P pubis may occur in individuals with short, thick, curly scalp hair.6
Clinical
History
- Patients may come to the attention of a health care provider after discovering lice or nits. Parents and teachers typically make the initial diagnosis of head louse infestation. In the case of head lice, a school nurse usually discovers infestation, or a generic letter is sent home to parents indicating that they should inspect their children for lice.
- Pruritus is the most common symptom of infestation. Children often have trouble sleeping because of intense pruritus at night when lice are feeding.
- Children with infestation may be asymptomatic. Routine nit inspections by school nurses are standard in many parts of the United States.
- Both combing and visual inspection have value in the diagnosis of lice infestation.7
Physical
Manifestations of head louse infestation include scalp pruritus, occipital lymphadenopathy, and impetigo. Examination of the scalp reveals excoriations, dark specks of louse dung, nits, and adult lice. The heaviest infestation typically is in the retroauricular scalp. Pruritus commonly leads to excoriation, secondary bacterial infection, and regional lymph node enlargement. A generalized exanthem rarely accompanies louse infestation (pityriasis rosealike pediculid).
- Pediculosis capitis: Although head lice may be found on any part of the scalp, they most commonly are found in the retroauricular scalp. Eggs depend on body warmth to incubate, so nits are attached to the hair shafts just above the level of the scalp. Human scalp hair grows at a rate of approximately 0.37 mm/d. Nits found several millimeters from the scalp are nonviable empty egg cases. They indicate chronic infestation.
- Pediculosis corporis: Body lice infest the seams of clothing and take blood meals at night. Nits are found in the seams, not on human hairs. Maculae ceruleae, the hemosiderin-stained purpuric spots where lice have fed, suggest the diagnosis of body louse infestation.
- Pediculosis pubis: Pubic lice and nits generally are plainly visible throughout the pubic hair, extending onto adjacent hairy areas of the body. Eyelash nits are a manifestation of pubic louse infestation, not head louse infestation.
More on Lice |
 Overview: Lice |
| Differential Diagnoses & Workup: Lice |
| Treatment & Medication: Lice |
| Follow-up: Lice |
| Multimedia: Lice |
| References |
| Next Page » |
References
Walsh J, Nicholson A. Head lice in children--a modern pandemic. Ir Med J. May 2005;98(5):156-7. [Medline].
Elston DM. Nit picking. J Am Acad Dermatol. Jul 2005;53(1):164-7. [Medline].
Elston DM. Drugs used in the treatment of pediculosis. J Drugs Dermatol. Mar-Apr 2005;4(2):207-11. [Medline].
Koehler JE, Sanchez MA, Garrido CS, et al. Molecular epidemiology of bartonella infections in patients with bacillary angiomatosis-peliosis. N Engl J Med. Dec 25 1997;337(26):1876-83. [Medline].
Brouqui P, Lascola B, Roux V, Raoult D. Chronic Bartonella quintana bacteremia in homeless patients. N Engl J Med. Jan 21 1999;340(3):184-9. [Medline].
Klaus S, Shvil Y, Mumcuoglu KY. Generalized infestation of a 3 1/2-year-old girl with the pubic louse. Pediatr Dermatol. Mar 1994;11(1):26-8. [Medline].
Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. Mar 2009;145(3):309-13. [Medline].
Williams LK, Reichert A, MacKenzie WR, Hightower AW, Blake PA. Lice, nits, and school policy. Pediatrics. May 2001;107(5):1011-5. [Medline].
Lwegaba A. Shaving can be safer head lice treatment than insecticides. BMJ. Jun 25 2005;330(7506):1510. [Medline].
Burkhart CN, Burkhart CG. Head lice: scientific assessment of the nit sheath with clinical ramifications and therapeutic options. J Am Acad Dermatol. Jul 2005;53(1):129-33. [Medline].
Bailey AM, Prociv P. Persistent head lice following multiple treatments: evidence for insecticide resistance in Pediculus humanus capitis. Australas J Dermatol. Nov 2000;41(4):250-4. [Medline].
Downs AM, Stafford KA, Harvey I, Coles GC. Evidence for double resistance to permethrin and malathion in head lice. Br J Dermatol. Sep 1999;141(3):508-11. [Medline].
Gonzalez Audino P, Barrios S, Vassena C, Mougabure Cueto G, Zerba E, Picollo MI. Increased monooxygenase activity associated with resistance to permethrin in Pediculus humanus capitis (Anoplura: Pediculidae) from Argentina. J Med Entomol. May 2005;42(3):342-5. [Medline].
Picollo MI, Vassena CV, Mougabure Cueto GA, Vernetti M, Zerba EN. Resistance to insecticides and effect of synergists on permethrin toxicity in Pediculus capitis (Anoplura: Pediculidae) from Buenos Aires. J Med Entomol. Sep 2000;37(5):721-5. [Medline].
Borkhardt A, Wilda M, Fuchs U, Gortner L, Reiss I. Congenital leukaemia after heavy abuse of permethrin during pregnancy. Arch Dis Child Fetal Neonatal Ed. Sep 2003;88(5):F436-7. [Medline].
Menegaux F, Baruchel A, Bertrand Y, et al. Household exposure to pesticides and risk of childhood acute leukaemia. Occup Environ Med. Feb 2006;63(2):131-4. [Medline].
Pearlman DL. A simple treatment for head lice: dry-on, suffocation-based pediculicide. Pediatrics. Sep 2004;114(3):e275-9. [Medline].
Pearlman DL. Nuvo lotion and the future of head-lice treatment. Pediatrics. May 2005;115(5):1452-3. [Medline].
Benzyl alcohol lotion 5% [package insert]. Atlanta, GA: Sciele Pharma Inc; 2009. [Full Text].
Roffe C. Treatment of pediculosis capitis by dry combing. Lancet. May 13 2000;355(9216):1724. [Medline].
Mumcuoglu KY, Magdassi S, Miller J, et al. Repellency of citronella for head lice: double-blind randomized trial of efficacy and safety. Isr Med Assoc J. Dec 2004;6(12):756-9. [Medline].
Burgess IF, Brown CM, Lee PN. Treatment of head louse infestation with 4% dimeticone lotion: randomised controlled equivalence trial. BMJ. Jun 18 2005;330(7505):1423. [Medline].
Burgess IF. Current treatments for pediculosis capitis. Curr Opin Infect Dis. Apr 2009;22(2):131-6. [Medline].
Toloza AC, Vassena C, Picollo MI. Ovicidal and adulticidal effects of monoterpenoids against permethrin-resistant human head lice, Pediculus humanus capitis. Med Vet Entomol. Dec 2008;22(4):335-9. [Medline].
Burgess IF. The mode of action of dimeticone 4% lotion against head lice, Pediculus capitis. BMC Pharmacol. Feb 20 2009;9:3. [Medline].
[Guideline] British Association for Sexual Health and HIV. United Kingdom national guideline on the management of phthirus pubis infestation. National Guideline Clearinghouse. Feb 2008.
[Guideline] Centers for Disease Control and Prevention, Workowski KA, Berman SM. Ectoparasitic infections. Sexually transmitted diseases treatment guidelines 2006. MMWR Morb Mortal Wkly Rep. Aug 4 2006;55(RR-11):79-80.
[Guideline] University of Texas, School of Nursing, Family Nurse Practitioner Program. Guidelines for the diagnosis and treatment of pediculosis capitis (head lice) in children and adults 2008. National Guidelines Clearinghouse. May 2008.
Permethrin. Nurs Times. May 31-Jun 6 2005;101(22):29. [Medline].
Barkwell R, Shields S. Deaths associated with ivermectin treatment of scabies. Lancet. Apr 19 1997;349(9059):1144-5. [Medline].
Bredal WP. Deaths associated with ivermectin for scabies. Lancet. Jul 19 1997;350(9072):216. [Medline].
Coyne PE, Addiss DG. Deaths associated with ivermectin for scabies. Lancet. Jul 19 1997;350(9072):215-6; author reply 216. [Medline].
Diazgranados JA, Costa JL. Deaths after ivermectin treatment. Lancet. Jun 7 1997;349(9066):1698. [Medline].
Reintjes R, Hoek C. Deaths associated with ivermectin for scabies. Lancet. Jul 19 1997;350(9072):215; author reply 216. [Medline].
Centers for Disease Control and Prevention. Unintentional topical lindane ingestions--United States, 1998-2003. MMWR Morb Mortal Wkly Rep. Jun 3 2005;54(21):533-5. [Medline].
Meinking TL, Taplin D. Safety of permethrin vs lindane for the treatment of scabies. Arch Dermatol. Aug 1996;132(8):959-62. [Medline].
Benenson AS, ed. Pediculosis. In: Control of Communicable Diseases in Man. 15th ed. Washington, DC: American Public Health Association; 1990:316-318.
Brown S, Becher J, Brady W. Treatment of ectoparasitic infections: review of the English-language literature, 1982-1992. Clin Infect Dis. Apr 1995;20 Suppl 1:S104-9. [Medline].
Burgess I. Head lice. Clin Evid. Dec 2004;2306-11.
Clore ER, Longyear LA. A comparative study of seven pediculicides and their packaged nit removal combs. J Pediatr Health Care. Mar-Apr 1993;7(2):55-60. [Medline].
Danes I, Enrique R. [Efficacy of pediculicidal drugs in pediculosis capitis]. Med Clin (Barc). Apr 9 2005;124(13):512-4. [Medline].
Halpern JS. Recognition and treatment of pediculosis (head lice) in the emergency department. J Emerg Nurs. Apr 1994;20(2):130-3. [Medline].
Hart G. Risk profiles and epidemiologic interrelationships of sexually transmitted diseases. Sex Transm Dis. May-Jun 1993;20(3):126-36. [Medline].
Hill N. Treatment of head lice. Lancet. Dec 9 2000;356(9246):2007; author reply 2008. [Medline].
Hipolito RB, Mallorca FG, Zuniga-Macaraig ZO, Apolinario PC, Wheeler-Sherman J. Head lice infestation: single drug versus combination therapy with one percent permethrin and trimethoprim/sulfamethoxazole. Pediatrics. Mar 2001;107(3):E30. [Medline].
Houhamdi L, Parola P, Raoult D. [Lice and lice-borne diseases in humans]. Med Trop (Mars). 2005;65(1):13-23. [Medline].
Ibarra J, Fry F, Wickenden C. Treatment of head lice. Lancet. Dec 9 2000;356(9246):2007; author reply 2008. [Medline].
Ibarra J, Hall DM. Head lice in schoolchildren. Arch Dis Child. Dec 1996;75(6):471-3. [Medline].
Meinking TL, Clineschmidt CM, Chen C, et al. An observer-blinded study of 1% permethrin creme rinse with and without adjunctive combing in patients with head lice. J Pediatr. Nov 2002;141(5):665-70. [Medline].
Peter G, ed. Pediculosis. In: 1997 Red Book: Report of the Committee on Infectious Diseases. 24th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 1997:387-390.
Plastow L, Luthra M, Powell R, Wright J, Russell D, Marshall MN. Head lice infestation: bug busting vs. traditional treatment. J Clin Nurs. Nov 2001;10(6):775-83. [Medline].
Pollack RJ, Kiszewski AE, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatr Infect Dis J. Aug 2000;19(8):689-93; discussion 694. [Medline].
Reynolds JEF, ed. Malathion. In: Martindale: The Extra Pharmacopoeia. 1996. ed. London, England: Pharmaceutical Press; 1437-1438.
Roberts RJ, Casey D, Morgan DA, Petrovic M. Comparison of wet combing with malathion for treatment of head lice in the UK: a pragmatic randomised controlled trial. Lancet. Aug 12 2000;356(9229):540-4. [Medline].
Sanford JP, Gilber DN. The Sanford Guide to Antimicrobial Therapy. 23rd ed. Vienna: Antimicrobial Therapy Inc; 1997.
Sendzik J, Stahlmann R. [Drugs for head lice. Toxicology and actions]. Med Monatsschr Pharm. May 2005;28(5):167-72. [Medline].
Sholdt L. The Epidemiology of Human Pediculosis in Ethiopia. Fort Collins: Colorado State University; 1976.
Tomalik-Scharte D, Lazar A, Meins J, et al. Dermal absorption of permethrin following topical administration. Eur J Clin Pharmacol. Jul 2005;61(5-6):399-404. [Medline].
Further Reading
Keywords
lice, lice infestation, pediculosis, louse infestation, nits
