Pediculosis (Lice) Differential Diagnoses

  • Author: Lyn Guenther, MD, FRCP(C), FAAD; Chief Editor: Burke A Cunha, MD   more...
 
Updated: Feb 9, 2012
 
 

Diagnostic Considerations

True nit infestation must be distinguished from hair casts (pseudonits). Hair casts are ringlike remnants of the inner root sheath of the hair follicle. They are amorphous and freely moveable along the hair fiber.

Many scalp conditions can cause pruritus. Seborrheic dermatitis presents as erythema and scale. It affects the scalp, eyebrows, nasolabial folds, and central chest. Acne necrotica presents with folliculitis with superficial pustules within scattered hair follicles. It is extremely pruritic, and patients pick at the lesions. Secondary follicular excoriations typically are noted on examination.

Free-living primitive psocid lice feed on decaying matter in leaves, old books, and animal habitats. They may cause human scalp infestation when children visit a library or doghouse that is infested. Psocids have large heads with massive jaws and are distinguished easily from Anoplura lice.

Other problems to be considered in the differential diagnosis of head louse infestation include the following:

  • Dandruff
  • Dried hairspray/gel
  • Dermatophyte infection
  • Piedra (black piedra from Piedraia hortae, white piedra from Trichosporon asahii and other species of Trichosporon)
  • Hair shaft abnormalities (ie, Monilethrix, trichorrhexis nodosa)

Other problems to be considered in the differential diagnosis of body louse infestation include the following:

Other problems to be considered in the differential diagnosis of pubic louse infestation include the following:

Proceed to Workup
 
 
Contributor Information and Disclosures
Author

Lyn Guenther, MD, FRCP(C), FAAD  Professor, Department of Medicine, Division of Dermatology, University of Western Ontario; Medical Director, The Guenther Dermatology Research Centre, Canada

Lyn Guenther, MD, FRCP(C), FAAD, is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Society for Dermatologic Surgery, Canadian Dermatology Association, Canadian Dermatology Foundation, Canadian Medical Association, Canadian Medical Protective Association, College of Physicians and Surgeons of Ontario, European Academy of Dermatology and Venereology, International Society for Dermatologic Surgery, Ontario Medical Association, Royal College of Physicians and Surgeons of Canada, Society for Investigative Dermatology, and Society for Pediatric Dermatology

Disclosure: L'Oreale Consulting fee Consulting; Johnson & Johnson Consulting fee Consulting

Coauthor(s)

Sheilagh Maguiness, MD  Assistant Clinical Professor, Department of Dermatology, University of California San Francisco School of Medicine; Associate Physician, Department of Dermatology, Kaiser Permanente

Sheilagh Maguiness, MD is a member of the following medical societies: American Academy of Dermatology, Canadian Dermatology Association, Canadian Medical Association, Society for Pediatric Dermatology, and Women's Dermatologic Society

Disclosure: Nothing to disclose.

Thomas W Austin, MD  Professor Emeritus, Department of Medicine, Division of Infectious and Sexually Transmitted Diseases, University of Western Ontario, Canada

Thomas W Austin, MD is a member of the following medical societies: Canadian Infectious Disease Society, College of Physicians and Surgeons of Ontario, Ontario Medical Association, and Royal College of Physicians and Surgeons of Canada

Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD  Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital

Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Additional Contributors

David F Butler, MD Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Edward F Chan, MD Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine

Edward F Chan, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, and Society for Investigative Dermatology

Disclosure: Nothing to disclose.

Pamela L Dyne, MD Professor of Clinical Medicine/Emergency Medicine, David Geffen School of Medicine at UCLA; Attending Physician, Department of Emergency Medicine, Olive View-UCLA Medical Center

Pamela L Dyne, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Dirk M Elston, MD, Director, Ackerman Academy of Dermatopathology, New York

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Joseph F John Jr, MD, FACP, FIDSA, FSHEA Clinical Professor of Medicine, Molecular Genetics and Microbiology, Medical University of South Carolina; Associate Chief of Staff for Education, Ralph H Johnson Veterans Affairs Medical Center

Disclosure: Nothing to disclose.

Daniel J Hogan, MD Clinical Professor of Internal Medicine (Dermatology), Nova Southeastern University College of Osteopathic Medicine; Investigator, Hill Top Research, Florida Research Center

Daniel J Hogan, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Contact Dermatitis Society, and Canadian Dermatology Association

Disclosure: Nothing to disclose.

Edmond A Hooker II, MD, DrPH, FAAEM Assistant Professor, Department of Emergency Medicine, University of Cincinnati College of Medicine

Edmond A Hooker II, MD, DrPH, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American Public Health Association, Society for Academic Emergency Medicine, and Southern Medical Association

Disclosure: Nothing to disclose.

Abdul-Ghani Kibbi, MD Professor and Chair, Department of Dermatology, American University of Beirut Medical Center, Lebanon

Disclosure: Nothing to disclose.

Rick Kulkarni, MD

Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: WebMD Salary Employment

David A Peak, MD Assistant Residency Director of Harvard Affiliated Emergency Medicine Residency, Attending Physician, Massachusetts General Hospital; Consulting Staff, Department of Hyperbaric Medicine, Massachusetts Eye and Ear Infirmary

David A Peak, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, Society for Academic Emergency Medicine, and Undersea and Hyperbaric Medical Society

Disclosure: Nothing to disclose.

Nelly Rubeiz, MD Consulting Staff, Department of Dermatology, American University of Beirut Medical Center; Associate Professor, Department of Dermatology, American University of Beirut, Lebanon

Nelly Rubeiz, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology

Disclosure: Nothing to disclose.

Robert A Schwartz, MD, MPH Professor and Head, Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School

Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and Sigma Xi

Disclosure: Nothing to disclose.

Russell W Steele, MD Head, Division of Pediatric Infectious Diseases, Ochsner Children's Health Center; Clinical Professor, Department of Pediatrics, Tulane University School of Medicine

Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, and Southern Medical Association

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

Jeter (Jay) Pritchard Taylor III, MD Compliance Officer, Attending Physician, Emergency Medicine Residency, Department of Emergency Medicine, Palmetto Health Richland, University of South Carolina School of Medicine; Medical Director, Department of Emergency Medicine, Palmetto Health Baptist

Jeter (Jay) Pritchard Taylor III, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, eMedicine

Disclosure: Nothing to disclose.

Wayne Wolfram, MD, MPH Associate Professor, Department of Emergency Medicine, Mercy St Vincent Medical Center

Wayne Wolfram, MD, MPH is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Pediatrics, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Neil W Yoder, DO Staff Physician, Department of Emergency Medicine, St Vincent Mercy Medical Center

Neil W Yoder, DO is a member of the following medical societies: American College of Emergency Physicians and Emergency Medicine Residents Association

Disclosure: Nothing to disclose.

Jeffrey M Zaks, MD Clinical Associate Professor of Medicine, Wayne State University School of Medicine; Vice President, Medical Affairs, Chief Medical Officer, Department of Internal Medicine, Providence Hospital

Jeffrey M Zaks, MD is a member of the following medical societies: American College of Cardiology, American College of Healthcare Executives, American College of Physician Executives, and American Medical Association

Disclosure: Nothing to disclose.

References

  1. Araujo A, Ferreira LF, Guidon N, et al. Ten thousand years of head lice infection. Parasitol Today. Jul 2000;16(7):269. [Medline].

  2. Walsh J, Nicholson A. Head lice in children--a modern pandemic. Ir Med J. May 2005;98(5):156-7. [Medline].

  3. Mumcuoglu KY, Gallili N, Reshef A, et al. Use of human lice in forensic entomology. J Med Entomol. Jul 2004;41(4):803-6. [Medline].

  4. Elston DM. Nit picking. J Am Acad Dermatol. Jul 2005;53(1):164-7. [Medline].

  5. Elston DM. Drugs used in the treatment of pediculosis. J Drugs Dermatol. Mar-Apr 2005;4(2):207-11. [Medline].

  6. Burkhart CN, Burkhart CG. Fomite transmission in head lice. J Am Acad Dermatol. Jun 2007;56(6):1044-7. [Medline].

  7. 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].

  8. Mimouni D, Ankol OE, Gdalevich M, et al. Seasonality trends of Pediculosis capitis and Phthirus pubis in a young adult population: follow-up of 20 years. J Eur Acad Dermatol Venereol. May 2002;16(3):257-9. [Medline].

  9. Mumcuoglu KY, Meinking TA, Burkhart CN, Burkhart CG. Head louse infestations: the "no nit" policy and its consequences. Int J Dermatol. Aug 2006;45(8):891-6. [Medline].

  10. Willems S, Lapeere H, Haedens N, et al. The importance of socio-economic status and individual characteristics on the prevalence of head lice in schoolchildren. Eur J Dermatol. Sep-Oct 2005;15(5):387-92. [Medline].

  11. Akisu C, Aksoy U, Delibas SB, Ozkoc S, Sahin S. The prevalence of head lice infestation in school children in izmir, Turkey. Pediatr Dermatol. Jul-Aug 2005;22(4):372-3. [Medline].

  12. Rupes V, Vlcková J, Mazánek L, Chmela J, Ledvinka J. [Pediatric head lice: taxonomy, incidence, resistance, delousing]. Epidemiol Mikrobiol Imunol. Aug 2006;55(3):112-9. [Medline].

  13. Bahamdan K, Mahfouz AA, Tallab T, Badawi IA, al-Amari OM. Skin diseases among adolescent boys in Abha, Saudi Arabia. Int J Dermatol. Jun 1996;35(6):405-7. [Medline].

  14. Leung AK, Fong JH, Pinto-Rojas A. Pediculosis capitis. J Pediatr Health Care. Nov-Dec 2005;19(6):369-73. [Medline].

  15. Foucault C, Ranque S, Badiaga S, et al. Oral ivermectin in the treatment of body lice. J Infect Dis. Feb 1 2006;193(3):474-6. [Medline].

  16. Elston DM. Treating pediculosis--those nit-picking details. Pediatr Dermatol. Jul-Aug 2007;24(4):415-6. [Medline].

  17. 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].

  18. 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].

  19. Williams LK, Reichert A, MacKenzie WR, Hightower AW, Blake PA. Lice, nits, and school policy. Pediatrics. May 2001;107(5):1011-5. [Medline].

  20. Lwegaba A. Shaving can be safer head lice treatment than insecticides. BMJ. Jun 25 2005;330(7506):1510. [Medline]. [Full Text].

  21. 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].

  22. Di Stefani A, Hofmann-Wellenhof R, Zalaudek I. Dermoscopy for diagnosis and treatment monitoring of pediculosis capitis. J Am Acad Dermatol. May 2006;54(5):909-11. [Medline].

  23. British Association for Sexual Health and HIV. United Kingdom national guideline on the management of phthirus pubis infestation. National Guideline Clearinghouse. Feb 2008.

  24. 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.

  25. 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.

  26. 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]. [Full Text].

  27. 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]. [Full Text].

  28. Stough D, Shellabarger S, Quiring J, Gabrielsen AA Jr. Efficacy and safety of spinosad and permethrin creme rinses for pediculosis capitis (head lice). Pediatrics. Sep 2009;124(3):e389-95. [Medline].

  29. Akisu C, Delibas SB, Aksoy U. Albendazole: single or combination therapy with permethrin against pediculosis capitis. Pediatr Dermatol. Mar-Apr 2006;23(2):179-82. [Medline].

  30. 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].

  31. 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].

  32. González Audino P, Barrios S, Vassena C, et al. 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].

  33. 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].

  34. Kristensen M, Knorr M, Rasmussen AM, Jespersen JB. Survey of permethrin and malathion resistance in human head lice populations from Denmark. J Med Entomol. May 2006;43(3):533-8. [Medline].

  35. Meinking TL, Entzel P, Villar ME, Vicaria M, Lemard GA, Porcelain SL. Comparative efficacy of treatments for pediculosis capitis infestations: update 2000. Arch Dermatol. Mar 2001;137(3):287-92. [Medline].

  36. Drugs for head lice. Med Lett Drugs Ther. Jan 17 1997;39(992):6-7. [Medline].

  37. Yoon KS, Gao JR, Lee SH, Clark JM, Brown L, Taplin D. Permethrin-resistant human head lice, Pediculus capitis, and their treatment. Arch Dermatol. Aug 2003;139(8):994-1000. [Medline].

  38. Lebwohl M, Clark L, Levitt J. Therapy for head lice based on life cycle, resistance, and safety considerations. Pediatrics. May 2007;119(5):965-74. [Medline].

  39. Chosidow O, Giraudeau B, Cottrell J, et al. Oral ivermectin versus malathion lotion for difficult-to-treat head lice. N Engl J Med. Mar 11 2010;362(10):896-905. [Medline].

  40. Barkwell R, Shields S. Deaths associated with ivermectin treatment of scabies. Lancet. Apr 19 1997;349(9059):1144-5. [Medline].

  41. Bredal WP. Deaths associated with ivermectin for scabies. Lancet. Jul 19 1997;350(9072):216. [Medline].

  42. Coyne PE, Addiss DG. Deaths associated with ivermectin for scabies. Lancet. Jul 19 1997;350(9072):215-6; author reply 216. [Medline].

  43. Diazgranados JA, Costa JL. Deaths after ivermectin treatment. Lancet. Jun 7 1997;349(9066):1698. [Medline].

  44. Reintjes R, Hoek C. Deaths associated with ivermectin for scabies. Lancet. Jul 19 1997;350(9072):215; author reply 216. [Medline].

  45. 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].

  46. 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].

  47. Pearlman DL. A simple treatment for head lice: dry-on, suffocation-based pediculicide. Pediatrics. Sep 2004;114(3):e275-9. [Medline].

  48. Pearlman DL. Nuvo lotion and the future of head-lice treatment. Pediatrics. May 2005;115(5):1452-3. [Medline].

  49. Benzyl alcohol lotion 5% [package insert]. Atlanta, GA: Sciele Pharma Inc; 2009. [Full Text].

  50. 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]. [Full Text].

  51. Burgess IF, Lee PN, Matlock G. Randomised, controlled, assessor blind trial comparing 4% dimeticone lotion with 0.5% malathion liquid for head louse infestation. PLoS One. Nov 7 2007;2(11):e1127. [Medline]. [Full Text].

  52. 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].

  53. Burgess IF. Current treatments for pediculosis capitis. Curr Opin Infect Dis. Apr 2009;22(2):131-6. [Medline].

  54. 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].

  55. Burgess IF. The mode of action of dimeticone 4% lotion against head lice, Pediculus capitis. BMC Pharmacol. Feb 20 2009;9:3. [Medline]. [Full Text].

  56. Izri A, Chosidow O. Efficacy of machine laundering to eradicate head lice: recommendations to decontaminate washable clothes, linens, and fomites. Clin Infect Dis. Jan 15 2006;42(2):e9-10. [Medline].

 
Previous
Next
 
Nit on a hair. Note the thin, translucent cement surrounding the hair shaft. Photo courtesy of David Shum, MD, Division of Dermatology, University of Western Ontario.
Nit from Pediculus humanus capitis on a hair.
Two empty nits from Pediculus humanus capitis. Note the open shells still attached to the hairs and the porous operculi through which the lice have hatched. Photo courtesy of David G. Schaus.
Three specimens of Pediculus humanus capitis.
Pediculus humanus corporis.
Phthirus pubis. Note the clawlike talus.
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.
 
 
 
All material on this website is protected by copyright, Copyright © 1994-2012 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.