Scabies

  • A very common but highly contagious ectoparasitic infestation of skin by human itch mite (Sarcoptes scabiei var hominis)
  • Predominantly though a disease of children it affects people of all races and social classes worldwide.
  • Intense itching, predominantly at night.
  • In day time it is tolerable but persistent.
  • In a person who has never had scabies before, symptoms take 6 weeks to appear because sensitivity begins about that period.
  • In a person who was infected earlier before, symptoms appear sooner (1-4 days).
  • SIGNS: Pruritic, papular or papulo-vesicular lesions, excoriations and burrows.
  • “Burrow” is the pathognomonic lesion of scabies, a serpentine, thread like, greyish or dark line ranging from few mm to cm or more.
  • Predominantly involves finger webs, wrist, axillae, areola, umbilicus, lower abdomen, genitalia and buttocks
  • forming an imaginary circle –
  • “circle of Hebra”.
  • In adults usually spares face and scalp.
  • In infants it involves entire skin.
  • Ulcerations and impetiginization due to scratching.
  • Secondary infection of ulcers with bacteria, like Stapylococcus aureus or beta hemolytic streptococci.
  • Sometimes post - streptococcal gromerulonephitis
  • Close person to person contact (even for 15-20 minutes).
  • Occasionally via fomites (e.g bedding or clothing).
  • In adults scabies is frequently sexually acquired.
  • Cannot be transferred by pets and animals.
  • Simultaneous treatment of all contacts, even if they are asymptomatic.
  • Avoiding direct skin to skin contact with infected person.
  • Bedding, clothing wash used at anytime during the 3 days before treatment should be washed and air dried.
  • Rooms used should be thoroughly cleaned and vaccum cleaned after use.
  • Environmental disinfection not necessary.
  • High humidity, low temperature.
  • Infested member in family or sexual partner.
  • In crowded conditions like jail inmates, hostels, army barracks where close body and skin contact is common.

How is it diagnosed?

  • Mainly diagnosed clinically
  • Demonstration of egg/ scybala / mite under microcope
  • Serological Tests: Less than 50% accuracy
  • Quantification of specific IgE antibodies to a major scabies antigen recombinant rSar s14.3 is highly sensitive
  • PCR, Immunosorbent Assays
  • Dermatoscopy

How is it treated?

  • Treat patient along with everyone who lives with him.
  • Recent sexual partner (if any).
  • Topicals to be applied whole body below neck in adults. In infants and children face and scalpe should be included.
  • All clothes worn along with bed sheet, pillow cover and bed linen should be washed and sundried in the morning.
  • Treatment not to exceed prescribed time limit.

Permethrin (5%)

Drug of choice at present

  • Most widely used, safe (even in children as young as 1 month old) and pregnant women.
  • Overnight application necessary.
  • Repeat the application after 7 days.
  • Cure rate of 89%-100%.
  • Insignificant irritant potential and adverse effects (2%).

LINDANE (GBHC 1%)

Benzoyl Benzoate 25%

Crotamiton 10% (Lotion / cream)

Ivermectin Solution

Precipitated Sulfur 5-10%

  • For secondary pyoderma.
  • Non irritant, non toxic antibacterial agents like Cetrimide / Chlorohexidine may help for topical use.

Ivermectin

  • Derivative of macrocyclic lactones.
  • Induces parasite paralysis by blocking neurotransmission.
  • Safety not established in children below 15 years and pregnant women.
  • Dose is 200 µg/kg/dose.
  • Two doses 2 weeks apart.
  • Neurotoxic.

Consult with experienced Doctors

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