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Phthirus pubis (pubic louse, cosmopolitan crab, Pediculus pubis)
Epidemiology:
- most commonly affects teenagers & young adults [5]
- transmission occurs by intimate contact, primarily during sexual intercourse
- can occur after contact with fomites such as clothing, bedding, & towels used by an infected person [5]
- pubic hair grooming associated with pubic lice [4]
Pathology:
- found primarily on pubic hairs, but may extend to the chest armpit & facial hair (including eyelashes)
Clinical manifestations:
1) intensely pruritic lesions & 2-3 mm bite macules (maculae ceruleae) develop at sites of bites
2) blepharitis accompanies infestations of eyelashes
3) patients may be asymptomatic
Special laboratory:
- dermoscopy (case report with image, video) [5]
Management:
1) topical permethrin 1% or malathion 0.5% kills both lice & eggs
2) on eyelids, apply petrolatum for 3-4 days
3) oral ivermectin effective (case report) [5]
Related
lindane (Kwell, Scabene)
pediculosis; phthiriasis (lice infestation, vagabond disease)
permethrin (Elimite, Nix)
General
Phthirus
Properties
KINGDOM: animal
PHYLUM: arthropod
ORGANISM-CLASS: INSECTA
ORDER: anoplura
FAMILY: pediculidae
GENUS: Phthirus
References
- Clinical Diagnosis & Management by Laboratory Methods,
19th edition, J.B. Henry (ed), W.B. Saunders Co.,
Philadelphia, PA. 1996, pg 1302
- Harrison's Principles of Internal Medicine, 13th ed.
Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 935-36
- Medical Knowledge Self Assessment Program (MKSAP) 15,
American College of Physicians, Philadelphia 2009
- Osterberg EC, Gaither TW, Awad MA et al
Correlation between pubic hair grooming and STIs: results from
a nationally representative probability.
Sex Transm Infect. Dec 5, 2016
PMID: 27920223
http://sti.bmj.com/content/early/2016/10/31/sextrans-2016-052687
- Fuentes-Suarez A, Gonzalez-Marquez TN
"Acrobatic" Lice.
N Engl J Med 2017; 377:e19October 5, 2017
PMID: 28976865
http://www.nejm.org/doi/full/10.1056/NEJMicm1700352