[STDs] Atlas of Pediculosis Pubis

These are the images, diagnosis and treatment of cases the disease caused by Pediculosis Pubis. This is a Cutaneous Infestations Diseases.

Pediculosis Pubis

Infestation with the crab louse (Phthirus pubis), or pediculosis pubis, is usually acquired through sexual contact with an infested person, but some cases probably result from exposure to shared clothes or bedding. P. pubis is adapted to survival in the pubic region, and Pediculus humanus to the head and body, by extremities adapted to grasping pubic hair or head and body hairs, respectively. Pruritus is common, but many patients are asymptomatic until eggs (nits) or lice are noticed. Maculae ceruleae, localized discoloration due to intracutaneous bleeding at sites of attachment, are rare but pathognomonic. Complications of pediculosis pubis are virtually unknown, and infestation is more a nuisance than a significant threat to health. Infestation is a marker of STD risk, and patients should be screened for other STDs.


Incidence and Prevalence
• Very common, but no reliable statistics available
• Diagnosed in 2–5% of patients attending some STD clinics

• Transmission occurs primarily by pubic area apposition with an infested person
• P. pubis is slowly motile and survives <24 hours without a blood meal, limiting nonsexual transmission; however, occasional cases may be transmitted through contaminated bedding or clothing

• No predilection; reflects sexual behavioral risks

• No special predilection 


Incubation Period
• Ova (nits) hatch in 5–10 days
• Hatched lice mature in 6–9 days and begin laying nits
• Symptoms may be delayed by several days or weeks, as pruritus is partly a consequence of allergy

• Visible nits or lice often are the only complaint
• Pubic area itching
• Lice appear nonmotile and may seem to adhere to skin, sometimes mistaken for scabs

Epidemiologic History
• Behavioral and population risks for STD
• Sexual contact with known case
• Sometimes communal living, typically in settings of poor hygiene

• Nits, attached at base of hair, are the most common sign of infestation
• Lice may be difficult to identify, particularly in dark-skinned patients
• Infestation usually limited to the pubic area, but sometime extends to thighs or trunk
• Eyelashes and eyebrows are occasionally involved, scalp rarely if ever
• Maculae ceruleae are pathognomonic but uncommon

• If diagnosis in doubt on visual inspection, suspected nits and lice may be examined microscopically

• Identification of nits or lice


Regimens of Choice
• Permethrin 1% cream rinse
• Pyrethrins with piperonyl butoxide
• Either treatment is applied to pubic area, intergluteal folds, and all skin surfaces from knees to waist, and to any other visibly infested areas except eyelashes
• Eyelash infestation: apply occlusive ophthalmic ointment to eyelid margins bid for 10 days

Alternative Regimens
• Resistance of pubic, body, and head lice to insecticides is widespread and increasing; use alternative
if infestation persists after initial treatment
° Malathion 0.5% lotion applied for 8–12 hours then rinsed
° Ivermectin 250 μg per kg body weight PO, repeated in 2 weeks (limited clinical experience)

• Main prevention strategies are sex partner selection and maintenance of personal hygiene
• Sex partners should be routinely treated 

Pubic louse infestation; Phthirus pubis and nits attached to pubic hairs.
13–1. Pubic louse infestation; Phthirus pubis and nits attached to pubic hairs.  


Patient Profile Age 33, male construction worker

History Pubic area itching for 1 week; noticed “white spots” clinging to pubic hair 1 day earlier; occasional causal sexual contacts

Examination Nits and typical crab lice in pubic hair; otherwise normal

Laboratory Urine NAAT for Chlamydia trachomatis and Neisseria gonorrhoeae, serological tests for
syphilis and HIV (all negative)

Diagnosis Pediculosis pubis

Treatment Permethrin 1% cream rinse

Partner Management Advised to inform partners and recommend attendance for clinical evaluation,
or self-treatment with over-the-counter preparations, e.g., pyrethrins with piperonyl butoxide lotion

Phthirus pubis nits (eggs) attached to pubic hairs
13–2. Phthirus pubis nits (eggs) attached to pubic hairs  

Phthirus pubis, the pubic louse, also called the crab louse
13–3. Phthirus pubis, the pubic louse, also called the crab louse. 

H. Hunter Handsfield, MD, Color Atlas & Synopsis of Sexually Transmitted Diseases, Third Edition.



Free Medical Atlas: [STDs] Atlas of Pediculosis Pubis
[STDs] Atlas of Pediculosis Pubis
These are the images, diagnosis and treatment of cases the disease caused by Pediculosis Pubis. This is a Cutaneous Infestations Diseases.
Free Medical Atlas
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