Scabies Overview and Treatment

Scabies

• Highly contagious skin condition caused by a mite, Sarcoptes scabiei.
• Transmission:
  • Direct contact with infected individual.
  • Indirect contact through contaminated items like towels or bedding.
• Incubation period: 2 weeks to 2 months.
• Characteristic lesion: Burrows, appearing as small lines on the skin, typically seen early in infection.
• Symptoms:
  • Intense itching, especially at night.
  • Other lesions include papules, vesicles, and crusting.
  • Distribution: Commonly found on the hands, wrists, elbows, axillae, abdomen, genitalia, and lower limbs.
• Types:
  • Human classic scabies: The most common type.
  • Animal scabies: Transmitted from animals to humans.
  • Scabies in infants: Atypical distribution, affecting the scalp, face, and soles.

Treatment of Scabies

• Topical scabicides:
  • Permethrin 5% (treatment of choice): Apply twice, 24 hours apart. Safe in infants and pregnant women.
  • Crotamiton 10%: Apply twice, 24 hours apart.
  • Benzyl benzoate 25%: Apply twice, 24 hours apart.
  • Sulfur 10% (adults) / 3-5% (infants): Apply every night for four nights. Safe in infants, children, and pregnant women.
  • Gamma benzene hexachloride 1%: Apply once for 12 hours. Not recommended for infants, children, pregnant or lactating women, or those with seizures.
  • Malathion 0.5%: Apply for 12 hours, then wash off.
  • Ivermectin 1% solution: Apply for 12 hours, then wash off. Repeat after a week.
• Systemic scabicides:
  • Oral Ivermectin: Effective against scabies. Dose: 6 mg/15 kg (0.2-0.4 mg/kg). Repeat after one or two weeks. Not recommended for children under 15 kg, pregnant or breastfeeding individuals.
• Additional treatment:
  • Antihistamines for itching.
  • Antibiotics for bacterial infections.

Nodular Scabies

• Treatment:
  • Intralesional steroid injection.
  • Surgical excision.

Causes of Persistent Itching After Scabies Treatment

• Hypersensitivity to mite antigens.
• Reinfection.
• Unsuccessful treatment.
• Irritation from scabicides.
• Acarophobia (fear of mites).

Pediculosis (Lice)

• Def: Infestation with lice, small blood-sucking parasites.
• Life cycle:
  • Females lay eggs (nits) that attach to the hair shaft.
  • Nits hatch within a week.

Pediculosis Capitis (Head Lice)

• Site: Scalp, primarily above the ears and occiput.
• Transmission: Direct contact or sharing hats, combs, and brushes.
• Symptoms:
  • Itching.
  • Nits visible on the hair shaft.
  • Possible impetigo and cervical lymphadenopathy.

Treatment of Pediculosis Capitis

• Step 1: Treat bacterial infections if present (e.g., impetigo) with systemic antibiotics.
• Step 2: Apply topical pediculicides after controlling bacterial infection:
  • Malathion 0.5%, Ivermectin 1%, or Permethrin 5%.
  • Apply to clean, dry hair for 12 hours, then wash off.
  • Repeat treatment after one week to ensure eradication.
• Nit removal:
  • Apply a vinegar solution (equal parts white vinegar and water) to loosen the glue holding nits to the hair.
  • Wash after 1-2 hours and comb hair with a fine-toothed comb to remove nits.
  • Oral Ivermectin: Alternative treatment, 0.2-0.4 mg/kg single dose, repeated after 8 days.

Pediculosis Pubis (Crab Lice)

• Transmission: Sexually transmitted.
• Site: Pubic and perineal hair. Can also affect eyelashes.
• Symptoms:
  • Intense itching.
  • Lice firmly attached to the base of hairs.

Urticaria (Hives)

• Def: Acute skin condition characterized by wheals (raised, red, itchy bumps).
• Causes:
  • Allergic reactions (e.g., food, drugs, pollen).
  • Non-allergic reactions (e.g., physical factors, infections).
• Symptoms:
  • Sudden appearance of itchy wheals that last for hours to 48 hours.
  • Wheals can be localized or generalized, ranging in size from small to large.
• Associated conditions:
  • Angioedema: Swelling in the skin and subcutaneous tissue (face, lips, genitalia).
  • General symptoms: Nausea, vomiting, dysphagia, hoarseness, wheezing, dyspnea.
• Types:
  • Acute urticaria: Symptoms last for less than 6 weeks.
  • Chronic urticaria: Symptoms last longer than 6 weeks.
• Special types:
  • Angioedema
  • Dermographism
  • Cold urticaria
  • Aquagenic urticaria
  • Cholinergic urticaria
  • Solar urticaria
  • Contact urticaria
  • Serum sickness

Treatment of Urticaria

• Primary focus: Identifying and removing the triggering cause.
• Medications:
  • Antihistamines: Primary treatment.
  • Systemic steroids: Adjuvant treatment for severe cases.
  • Adrenaline, calcium gluconate (in severe, life-threatening cases).

Papular Urticaria (Prurigo Simplex)

• Def: Hypersensitivity reaction to insect bites (e.g., fleas, mosquitos).
• Symptoms:
  • Occurs mostly in infants and children.
  • Itchy red papules (1-5 mm).
  • Lesions located primarily on the limbs; occasionally on the trunk.
• Course:
  • Often subsides spontaneously, even with continued exposure to insects.
  • Desensitization to insect antigens may occur over time.
• Prurigo of Hebra (Atopic prurigo):
  • Persistent form of papular urticaria, especially in individuals with atopic dermatitis (eczema).
  • Characterized by numerous, lichenified (thickened) lesions, excoriated papules, and superficial lymphadenopathy.

Atopic Dermatitis (Eczema)

• Diagnosis: Four major criteria should be present.
  • Pruritis (itching)
  • Typical morphology and distribution for age group.
  • Chronic or chronically relapsing dermatitis.
  • Personal or family history of atopy (allergies, asthma, eczema).

Treatment of Atopic Dermatitis

• General measures:
  • Environment modifications.
  • Avoid triggers (e.g., irritating clothing, skin products, allergens).
• Medications:
  • Oral antihistamines.
  • Short-course systemic steroids for extensive cases.
  • Topical soothing lotions or corticosteroids.

This quiz provides essential information about scabies, a highly contagious skin condition caused by the mite Sarcoptes scabiei. Explore its transmission methods, symptoms, and effective treatments, including topical scabicides. Test your knowledge on scabies types and management strategies.