Body louse

Author: Priya Nagarajan, M.D., Ph.D. and Liye Suo, M.D. (see Authors page)

Revised: 21 October 2016, last major update October 2016

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Body louse

Cite this page: Body louse. website. Accessed October 26th, 2016.
Definition / General
  • Defined as infestation caused by body louse (Pediculus humanus corporis)
  • Skin lesions due to direct bite, hypersensitivity reaction and itching related excoriation
  • Louse is also vector for other diseases such as epidemic typhus, trench fever and relapsing fever
  • Pediculosis, Pediculus humanus corporis
  • Found worldwide and affects people of all races and social classes (CDC)
  • Highest in endemic areas, young, elderly, immunocompromised, nursing home residents and resource poor, overcrowded populations (Rev Chil Pediatr 2014;85:312)
  • Lice live and lay eggs in clothing and bedding
  • Usually do not live on human body, but are found only when they feed
  • Body lice prefer lower temperature and live and lay eggs in clothing and bedding
  • Lice are bloodsucking insects, feeding ~ 5 times a day by biting host
  • Small amount of louse saliva is injected into host during feeding, causing mild hypersensitivity reaction and associated pruritus
  • Lice are vector for epidemic typhus (Rickettsia prowazeki), trench fever (Bartonella quintana) and relapsing fever (Borrelia recurrentis) (Clin Microbiol Infect 2012;18:332, Clin Lab Med 2015;35:847)
Clinical Features
  • Intense itching and irritation of the body
  • Extensive excoriation, serous crusting and scaling on the body
  • Identification: Body lice are about the size of sesame seeds and are found on clothing and bedding, while nits are found in seams of clothing or rarely attached to body hair
  • Can be associated with secondary infections such as epidemic typhus, trench fever and relapsing fever (Infect Genet Evol 2014;23:209)
  • Thorough physical examination
  • Dermatoscopy is a non invasive technique important for the diagnosis of skin infestation diseases (Clin Dermatol 2014;32:315)
  • Histology examination is useful to find the diagnostic organism and to establish dermal hypersensitivity reactions associated with insect bites
Case Reports
  • Improving personal hygiene
  • Systemic medication: oral ivermectin (Dermatol Online J 2016:16;22)
  • Topical treatment: Lindane shampoo, benzyl alcohol 5% and permethrin
  • Prevention: Improving personal hygiene, regular washing of clothes and avoiding direct physical contact with those who carry body lice
Clinical Images

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Body louse

Scalp infection and scraping lesions

Micro Description
  • Skin lesion: Perivascular lymphohistiocytic infiltrate mixed with variable numbers of eosinophils, arranged in a wedge shape that tapers towards deep dermis, rarely intradermal hemorrhage
  • Body lice: 3 - 4 mm long, 3 pairs of legs, elongated body and thin head with narrow mouth parts
  • Nits (eggs): small white structures, 1 mm long, teardrop shaped, translucent with apical operculum
Differential Diagnosis