Phthirus pubis infestation (pubic lice) is usually spread by sexual contact. Blue macules about 3 mm in diameter develop at bite sites. Patients are often co-infected with another STD. Patients present with intense itching and have lice or nits (pubic, chest, abdominal, leg, eyelash, and head hair).
CASES/YEAR
875,000 (US); 17,500,000 (Global)
OTHER NAMES
Crab or pubic lice (Phthirus pubis);
INCUBATION
7-8 days (egg incubation); 17-22 days (life span); [PPID, p. 3484]
INITIAL SYMPTOMS
Itching;
PRECAUTIONS
Contact until 24 hours after initiation of effective therapy; [CDC 2007 Guideline for Isolation Precautions] "Under suitable environmental conditions, head and crab lice eggs can remain viable away from the host for up to 7-10 days;" [CCDM, p. 447]
COMMENTS
Pubic lice are usually spread by sexual contact. Blue macules about 3 mm in diameter develop at bite sites. [Harrison ID, p. 1177] Lice can survive away from the body for 10 days. Pubic lice can infest pubic, axillary, head, and eyelash hair. Test all patients with pubic lice for STDs and treat all contacts. [ABX Guide] Patients are often co-infected with another STD. Patients present with intense itching and have lice or nits (pubic, chest, abdominal, leg, eyelash, and head hair). [Cecil, p. 692] Children may be infected after close parental contact. Fomites (towels, bedding, and clothing) may spread infection. Louse excreta (dark brown specks) may be found on skin and underwear. [Merck Manual, p. 1058]
DIAGNOSTIC
May find blue spots (maculae ceruleae) on trunk, thighs, and upper parts of arms; Lice look like scabs in a scratching area, but if placed on a slide, they walk away; [ABX Guide]
SIGNS & SYMPTOMS
-
H lymphadenopathy
-
S lymphadenitis, acute
-
S papules or plaques
-
S urticaria
ENTRY
Skin or Mucous Membranes (Includes Conjunctiva), Sexual Contact
REFERENCES FOR CASES/YEAR
1. (US) 1/20 X global cases/yr;
2. (Global) Incidence of 3.5% in STD clinics has been reported; [Gorbach, p. 242] 1 million STIs /day; Each year 500 million cases of Chlamydia, Gonorrhea, Syphilis, and Trichomonas; [Fact sheets from WHO 2013] Calculate: 0.035 X 500 million = 17,500,000;