Definition

Pediculosis pubis, commonly known as pubic lice, refers to an infestation of lice in the pubic or genital region. The pubic region comprises the bony prominence above the genitals, typically adorned with genital hair. This condition, prevalent across global populations regardless of race, ethnicity, or social status, manifests in people worldwide.

Causes

Pediculosis pubis results from an infestation of small lice known as Pthirus pubis. These lice differ from those typically found on the head and body. Adult pubic lice measure approximately 1 to 1.8 millimeters in length and sustain themselves by feeding on blood. The life cycle of pubic lice encompasses three stages:

• Egg: Lice eggs, or nits, are often challenging to see and typically attach to the hair shaft. They exhibit an oval shape and range in color from yellow to white. Lice eggs usually need 6 to 10 days before hatching.
• Nymph: Nymphs represent immature lice that have recently hatched. They share a similar shape to adult lice but are smaller in size. Nymphs undergo a development period of 2 to 3 weeks following hatching, in which they mature into adult lice capable of reproduction. Like their adult counterparts, nymphs must consume blood to develop.
• Adult lice: Adult pubic lice bear a resemblance to crabs when observed under magnifying glass. They possess six legs, with prominently large front legs reminiscent of crabs. These lice typically exhibit color ranging from brown to grayish white. Female lice tend to be larger than their male counterparts and are responsible for laying lice eggs. Adult lice rely on blood for sustenance, and if deprived of their food source after falling from human's hair, they will perish within 1 to 2 days.

Transmission of pubic lice primarily occurs through sexual activity, particularly in adults. In children, pubic lice may also infest the eyebrows or eyelashes, which could indicate potential sexual abuse. However, transmission can also occur through the sharing of clothing, bed linens, or towels with an infected person. It's important to note that dogs, cats, or other pets cannot transmit pubic lice to humans.

There's a common misconception regarding the ease of transmission of pubic lice by sitting in public toilets. This type of transmission is exceedingly rare. because pubic lice require a human host to survive, and they lack the ability to survive for extended periods without a human body. Moreover, their legs could not grip or traverse on smooth surfaces such as toilet seats.

Risk factor

Several factors can increase an individual's risk to pubic lice exposure, including:

• They have sexually transmitted infections
• Engaging in sexual activity with individuals affected by pubic lice
• Poor genital hygiene practices
• Infrequently changing their underwear

Symptoms

Bites of lice can trigger severe itching in the genital region, and both lice eggs and lice that move could be visible to the eyes. Additionally, lice can migrate to other regions with coarse hair, including:

• Limbs
• Chest
• Armpits
• Mustache or beard
• Eyelashes and eyebrows (more prevalent in children)
• Area surrounding the anus

It's worth noting that lice infesting the hair are referred to as head lice (pediculosis capitis), distinct from pubic lice (pediculosis pubis).

Diagnosis

Doctors typically confirm a diagnosis of pediculosis pubis through visual inspection of the pubic area or other hairy regions. The finding of active lice in the genital region confirms the diagnosis. Moreover, the presence of lice eggs or nits in the genital may suggest pediculosis pubis, although eggs can persist and attach to the hair even after successful treatment. While lice and their eggs are usually visible to the naked eye, a magnifying lens may be necessary for detecting the lice in some cases.

Given the potential for lice to migrate from the treated area to other hairy regions, doctors will also examine other parts of the body during evaluation. If you are diagnosed with pediculosis pubis, it's advisable to undergo screening for other sexually transmitted infections as well.

Management

Treatment for pediculosis pubis typically involves using a cream that kills both lice and their eggs. Over-the-counter medicine options include 1% permethrin or pyrethrin shampoos, which are safe and effective when used as instructed in the labels. If initial treatment fails to eradicate the genital lice infestation, a doctor may prescribe stronger medicines, such as:

• Malathion 0.5%. The lotion or cream is applied to the affected area and left on for 8 to 12 hours before being rinsed off. This medicine could effectively target lice and their eggs.
• Ivermectin. Available in pill form, typically taken as a single dose or in two doses, with the second pill taken 10 days after the first pill if necessary, where the first pill did not kill the lice.
• Lindane Shampoo. This is another treatment option capable of eliminating pubic lice and their eggs. However, due to its potential toxicity to the brain and nervous system, it is not recommended as initial therapy for pubic lice. Lindane shampoo is typically reserved for individuals who do not respond to other treatments or whose skin cannot tolerate alternative products. It should not be used in certain populations, including babies, people with seizure disorders, pregnant or breastfeeding women, those with skin disorders, children, elderly, or thin individuals.
• Treating eyelashes and eyebrows. For treating pubic lice found around the eyelashes and eyebrows, the treatment could involve petroleum jelly. This entails applying petroleum jelly using a cotton swab at night and washing it off in the morning. This regimen should be repeated for several weeks, however, it's important to be cautious as improper application could irritate the eyes. Alternatively, if only a few lice and eggs are present, they can be manually removed using a comb or fingernail. In some cases, a doctor may prescribe a special ointment for treatment.

Shaving your hair will not help get rid of pediculosis pubis. Treating pediculosis pubis requires patience and thoroughness in both personal hygiene and cleaning your potentially contaminated belongings. Here are some steps you can take:

• Use Cream and Shampoo. Opt for over-the-counter creams and shampoos specifically designed to kill pubic lice. Follow the instructions provided with the product carefully. In some cases, you may need to repeat the treatment 7 to 10 days after the first application.
• Wash Contaminated Items. Wash all bed linens, clothing, towels, and other items that may have come into contact with your body within the last two days before starting treatment. Wash these items in hot (at least 54 degrees Celsius), soapy water and then dry them at a high temperature for a minimum of 20 minutes. 
• For items that cannot be washed, consider dry-cleaning them or storing them in airtight plastic bags for at least two weeks.

Complications

Genital lice infections can typically be effectively treated with ointments such as creams or gels that target the lice. However, in some cases, pediculosis pubis can lead to complications such as:

• Changes in Skin Color. Continued feeding of blood by lice can lead to the formation of pale blue spots on the skin.
• Secondary Infection. Severe itching from lice bites may lead to intense scratching, resulting in open wounds that can become infected.
• Eye Irritation. In children with pubic lice affecting the eyelashes, it can lead to red eyes (conjunctivitis or inflammation of the lining of the eyeball).

Prevention

To prevent contracting pediculosis pubis, it's important to avoid sexual contact or sharing personal items such as bedding, clothing, and towels with infected individuals. If you're undergoing treatment for pediculosis pubis, it's crucial for all your sexual partners to also undergo treatment to break the chain of transmission.

When to see a doctor?

You should consult a doctor if:

• You have attempted to treat the lice with over-the-counter medications but your conditions do not improve
• You are currently pregnant
• Your skin becomes infected or develops sores due to intense scratching

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