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Pediculosis – Comprehensive Medical Guide

Overview

Pediculosis is the medical term for an infestation of lice (order Phthiraptera) on the human body. The three most common types are:

• Head lice (Pediculus humanus capitis) – live on the scalp and hair shafts.
• Body lice (Pediculus humanus corporis) – reside in clothing seams and move to the skin to feed.
• Pubic (crab) lice (Pthirus pubis) – attach to the coarse hair of the genital area, but can also be found on chest, abdomen, or facial hair.

Lice are obligate ectoparasites that feed on human blood. Infestations are not a sign of poor hygiene, but they can cause itching, secondary skin infections, and social distress.

Sources: Mayo Clinic¹, CDC², NIH³

Symptoms Checklist

Use the checklist below to see if you or someone you care for may have pediculosis.

• ☐ Persistent itching, especially on the scalp, neck, or genital area.
• ☐ Visible live lice on hair shafts, clothing seams, or pubic hair.
• ☐ Small, white or yellowish nits (lice eggs) firmly attached to hair shafts close to the scalp.
• ☐ Red or irritated skin from scratching.
• ☐ Small, painless bumps (papules) where lice have fed.
• ☐ Secondary bacterial infection (e.g., impetigo) – appears as crusted, pus‑filled lesions.

Sources: CDC², Cleveland Clinic⁴

Risk Factors

• Close personal contact (e.g., schoolchildren, family members sharing beds).
• Living in crowded or unsanitary conditions.
• Sharing personal items such as hats, combs, hair accessories, bedding, or clothing.
• Travel to areas where lice are endemic.
• Having a household member with a known infestation.
• Reduced access to regular laundering facilities.

Sources: CDC², Johns Hopkins⁵

Diagnosis

Diagnosis is primarily clinical and involves a visual inspection:

1. Head & Pubic Lice: Use a fine‑tooth comb on wet hair under a bright light. Look for live lice (≈2–4 mm) and nits attached within ¼ inch of the scalp.
2. Body Lice: Examine clothing seams, especially undergarments and socks, for moving insects or nits.
3. Microscopic Confirmation: In uncertain cases, a sample can be examined under a microscope.

Dermatologists may also perform a “wet mount” of skin scrapings to differentiate lice from other parasites.

Sources: Mayo Clinic¹, NIH³

Treatment Options

Medical Treatments

• Topical Pediculicides (approved by the FDA):
  • 1% Permethrin lotion or shampoo – applied to dry hair, left for 10 minutes, then rinsed. Repeat in 7–10 days.
  • 5% Malathion lotion – for resistant head‑lice infestations; leave on for 8–12 hours before washing.
  • Spinosad 0.9% suspension – a single 10‑minute application; effective against many resistant strains.
• Oral Ivermectin – used for refractory cases or body‑lice infestations; dosage is weight‑based and prescribed by a physician.
• Prescription‑strength shampoos (e.g., benzyl alcohol 5% lotion) – alternative for patients who cannot tolerate permethrin.

Home & Supportive Care

• Fine‑tooth nit combing every 2–3 days for 2 weeks.
• Wash all bedding, clothing, and personal items in hot water (≥130 °F/54 °C) and dry on high heat for at least 20 minutes.
• Seal non‑washable items (e.g., stuffed toys) in a sealed plastic bag for 2 weeks.
• Apply soothing lotions (e.g., calamine) to relieve itching.
• Avoid scratching to reduce secondary infection risk.

Sources: CDC², Cleveland Clinic⁴, Mayo Clinic¹

Prevention

• Do not share hats, scarves, hairbrushes, or headphones.
• Encourage regular hair‑checking in schools and daycare centers.
• Keep personal items (bedding, towels) separate and launder frequently.
• Use a protective “no‑nit” policy only when medically indicated; avoid unnecessary exclusion of children.
• Educate family members about the life cycle of lice (egg → nymph → adult ≈ 7 days) to understand treatment timing.
• For body lice, maintain clean clothing and change underwear daily; provide access to laundry facilities in high‑risk settings.

Sources: CDC², Johns Hopkins⁵

Living With Pediculosis

Even after successful treatment, vigilance is key to prevent re‑infestation.

• Routine Checks: Perform a quick scalp inspection once a week for the first month.
• Maintain Cleanliness: Wash hats, scarves, and pillowcases weekly during the outbreak period.
• Family Coordination: Treat all close contacts simultaneously to break the transmission cycle.
• Psychosocial Support: Reassure children that lice are common and treatable; avoid stigma.
• Document Treatment: Keep a log of medication dates, combing sessions, and laundry cycles.

Sources: Mayo Clinic¹, Cleveland Clinic⁴

When to Seek Emergency Care

Pediculosis itself is rarely a medical emergency, but certain complications require prompt attention:

• Signs of a severe secondary bacterial infection (e.g., rapidly spreading redness, warmth, pus, fever).
• Allergic reaction to a topical treatment (e.g., swelling of the face, difficulty breathing, hives).
• Persistent itching and skin breakdown leading to extensive excoriation.
• Infants younger than 2 months with head‑lice infestation (treatment options are limited).

If any of these occur, seek care at an urgent‑care center or emergency department immediately.

Sources: CDC², NIH³

``` **References** 1. Mayo Clinic. “Head lice: Symptoms and causes.” https://www.mayoclinic.org/diseases-conditions/head-lice/symptoms-causes/ 2. Centers for Disease Control and Prevention (CDC). “Pediculosis (Lice) – Treatment.” https://www.cdc.gov/parasites/lice/treatment.html 3. National Institutes of Health (NIH) – MedlinePlus. “Lice (Pediculosis).” https://medlineplus.gov/lice.html 4. Cleveland Clinic. “How to Get Rid of Lice.” https://my.clevelandclinic.org/health/diseases/21173-lice 5. Johns Hopkins Medicine. “Lice (Pediculosis) – Diagnosis and Management.” https://www.hopkinsmedicine.org/health/conditions-and-diseases/lice *All URLs accessed September 2024.*