Pediculosis (Lice) Workup

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

Approach Considerations

Because the diagnosis of infestation requires identification of a live louse and/or a viable nit, examining suggestive particles under the microscope confirms the diagnosis. Cellulose tape can be applied over an infested area to pick up lice and place them on a microscopic slide to be examined. A Wood lamp examination of the area considered to be infested shows yellow-green fluorescence of lice and nits. Dermoscopy can be used to reliably differentiate nymph-containing eggs from empty cases or pseudonits.[22]

Infestation with Pediculus pubis is a sexually transmitted disease (STD), and 30% of these patients have an addition STD. Thus, it is appropriate to screen these patients for other STDs, including human immunodeficiency virus (HIV), syphilis, gonorrhea, chlamydia, genital herpes, and trichomoniasis.

Scrapings for a fungal culture can be collected if dermatophyte infection is in the differential diagnosis. This is useful when the diagnosis is unclear (ie, no nits or lice have been identified).

Properly evaluating persons who have been raped is essential. Evidence should be collected in such a way as to avoid contamination and to ensure a legal chain of custody. Human DNA can now be identified in the amount of blood present in a pubic louse. Lice recovered after an attack have the potential to provide evidence valuable in securing a conviction.

Histology is rarely required for diagnosis. Examination of a bite shows intradermal hemorrhage and a deep, wedge-shaped infiltrate with many eosinophils and lymphocytes.

Louse bites demonstrate intradermal hemorrhage and a polymorphous wedge-shaped infiltrate rich in eosinophils.

Proceed to Treatment & Management
 
 
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.

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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.
 
 
 
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