Pediculosis (lice)

Skin inflammatory (nontumor)
Infestations
Pediculosis (lice)

Author: Mowafak Hamodat, M.B.Ch.B., M.Sc.

Topic Completed: 1 July 2011

Revised: 2 April 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Pediculosis[TI] lice[TIAB]

Page views in 2018: 156

Page views in 2019 to date: 275

Table of Contents

Cite this page: Hamodat M Pediculosis (lice). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorpediculosis.html. Accessed November 12th, 2019.

Definition / general

Causes pruritis, enlarged local lymph nodes
Eggs are attached to hair shaft (nits)

Terminology

Pediculus humanus has 2 subspecies: P. h. humanus (body louse) and P. h. capitis (head louse) (CDC: Pediculosis [Accessed 15 October 2018])

Diagrams / tables

Images hosted on other servers:

Life cycle of Pediculus humanus capitis

Case reports

Young child from Southwest Asia had male Pediculus humanus crawl out of nostril (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 507 [Accessed 15 October 2018])

Treatment

Careful shampooing and combing to remove nits, followed up by heat treatment (CDC: Head Lice - Treatment [Accessed 9 November 2018])
May be resistance to topical pediculicides

Gross description

Key identifying features of Pediculus humanus (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 507 [Accessed 15 October 2018]):
- Small body (1 - 2 mm long)
- 6 legs
- Dorsoventrally flattened
- Wingless
- Raptorial (grasping) claws
- Fused thorax, distinct from the head (with antennae) and abdomen
- Enlongated body

Gross images

Contributed by Bobbi Pritt, M.D.

Male Pediculus humanus

P. h. capitis

Microscopic (histologic) images

Images hosted on other servers:

Nits

Differential diagnosis

P. h. humanus and P. h. capitis: not possible to tell apart by morphology alone since there is significant overlap in sizes between the 2 otherwise identical subspecies (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 507 [Accessed 15 October 2018])

Additional references

eMedicine: Pediculosis and Pthiriasis (Lice Infestation) [Accessed 15 October 2018], Wikipedia: Louse [Accessed 15 October 2018], CDC: Lice [Accessed 15 October 2018]