Scabies

Scabies

“Scabies.” I know that you are already itching. Soon it will be uncontrollable. The Ped EM Morsels have covered several conditions that cause pruritus (ex, Eczema, Tinea Capitis, Hyperbilrubinemia) as well as a general approach to Rashes, but nothing will make a patient, or a clinician, more uncomfortable than the potential for the patient having Scabies!

 

Scabies: The Ultimate Itch

  • Scabies is a skin disease causes by infestation of a mite, Sarcoptes scabiei var. hominis.
  • The mite burrows into the top layers of skin, where the female will lay her eggs.
  • After 4-6 weeks, patients develop an allergic type reaction to the mite’s proteins and feces.
  • Intense pruritus leads to problems!
    • The itch leads to lots of scratching.
    • Lots of scratching leads to mechanical injury to the skin.
    • Skin injury allows for secondary bacterial infections (Staph and Strep) and complications:
      • Suppurative complications
        • Impetigo
        • Cellulitis
        • Subcutaneous abscesses
        • Sepsis
      • Non-Suppurative complications
        • Acute post-streptococcal glomerulonephritis
          • ~50% of acute post-strep GN in tropical settings is due to skin infection. [WHO]
        • Rheumatic heart disease
          • Scabies related skin infections offers an explanation of high rheumatic heart disease rates in countries with low rates of strep pharyngitis. [Parks, 2012]

 

Scabies: Under-appreciated

  • Scabies is more than a nuisance and control is a challenge. [Engelman, 2013]
  • Scabies is one of the most prevalent skin conditions worldwide.
    • 130 MILLION people have scabies at any one time worldwide. [WHO]
    • Effects ~5-10% of children in developing countries.
  • Effects people from every country, but is most prevalent in at risk populations:
    • Populations with poor access to resources
    • Young
    • Elderly

 

Scabies: Different in Children

  • Children may present with different clinical findings than adults.
  • Infants are more likely to have: [Boralevi, 2014]
    • Facial / Scalp involvement
    • Palm and plantar lesions
    • Dorsum of the forefoot lesions!
  • Children (2-15 yrs) are more likely to have relapses. [Boralevi, 2014]
  • Burrows are observed in all age groups, but not necessary for the diagnosis.
  • Nodules also are seen in all age groups, but in infants more often in axilla and back locations.
  • Look actively for burrows, axillary nodules and involvement in the soles, dorm of the forefoot, and scalp/face! [Boralevi, 2014]

 

Scabies: Treatments

  • No treatment is perfect.
  • Summarized nicely by Mousey and McCarthy [2013]
  • Permethrin 5% Topical
    • 1st line in many countries
    • Good safety profile and effective
    • Recommended to apply twice (2nd treatment 1 week after 1st treatment) to kill residual eggs that subsequently hatch.
    • Limitation = expensive cost
  • Benzyl Benzoate Topical
    • Dosage: Adults – 25%; children 10-12.5%
    • Highly efficacious
    • Inexpensive
    • Not available in the USA.
    • Limitation = significant skin irritation that occurs immediately, limiting tolerance
  • Ivermectin
    • Off-label in most countries, but known to be effective.
    • Oral 
      • Dose = 200 micrograms/kg; two doses, 2nd dose 1 week after 1st.
      • Used to treat Crusted Scabies (high mite burden) and for treatment of large groups of patients.
      • Not approved for kids < 15 kg or in pregnant / lactating women (who often have high burden of disease)
    • Topical
      • Dose = 1%
      • More effective than single dose of oral.
  • Other treatment considerations
    • Antihistamines
    • Avoidance of Lindane – less effective than other therapies and has adverse neurologic sequelae.
    • Topical corticosteroids are not recommended as they may mask treatment failure.
    • Treatment Failure:
      • Challenging to determine as clinical pruritus will continue even after appropriate therapy.
      • Most likely causes of treatment failure:
        • Inadequate therapy or application of topical treatment
        • Re-infestation (so consider treatment of contacts)
        • Mite resistance (less likely than the 1st two).

 

References

Romani L1, Steer AC2, Whitfeld MJ3, Kaldor JM4. Prevalence of scabies and impetigo worldwide: a systematic review. Lancet Infect Dis. 2015 Aug;15(8):960-7. PMID: 26088526. [PubMed] [Read by QxMD]

Ahmad HM1, Abdel-Azim ES1, Abdel-Aziz RT1. Clinical efficacy and safety of topical versus oral ivermectin in treatment of uncomplicated scabies. Dermatol Ther. 2015 Nov 11. PMID: 26555785. [PubMed] [Read by QxMD]

Boralevi F1, Diallo A, Miquel J, Guerin-Moreau M, Bessis D, Chiavérini C, Plantin P, Hubiche T, Maruani A, Lassalle M, Boursault L, Ezzedine K; Groupe de Recherche Clinique en Dermatologie Pédiatrique. Clinical phenotype of scabies by age. Pediatrics. 2014 Apr;133(4):e910-6. PMID: 24685953. [PubMed] [Read by QxMD]

Chung SD1, Wang KH, Huang CC, Lin HC. Scabies increased the risk of chronic kidney disease: a 5-year follow-up study. J Eur Acad Dermatol Venereol. 2014 Mar;28(3):286-92. PMID: 23374101. [PubMed] [Read by QxMD]

Rosamilia LL1. Scabies. Semin Cutan Med Surg. 2014 Sep;33(3):106-9. PMID: 25577847. [PubMed] [Read by QxMD]

Engelman D1, Kiang K, Chosidow O, McCarthy J, Fuller C, Lammie P, Hay R, Steer A; Members Of The International Alliance For The Control Of Scabies. Toward the global control of human scabies: introducing the International Alliance for the Control of Scabies. PLoS Negl Trop Dis. 2013 Aug 8;7(8):e2167. PMID: 23951369. [PubMed] [Read by QxMD]
Mounsey KE1, McCarthy JS. Treatment and control of scabies. Curr Opin Infect Dis. 2013 Apr;26(2):133-9. PMID: 23438966. [PubMed] [Read by QxMD]

Parks T1, Smeesters PR, Steer AC. Streptococcal skin infection and rheumatic heart disease. Curr Opin Infect Dis. 2012 Apr;25(2):145-53. PMID: 22327467. [PubMed] [Read by QxMD]

Nolan K1, Kamrath J, Levitt J. Lindane toxicity: a comprehensive review of the medical literature. Pediatr Dermatol. 2012 Mar-Apr;29(2):141-6. PMID: 21995612. [PubMed] [Read by QxMD]

Bouvresse S1, Chosidow O. Scabies in healthcare settings. Curr Opin Infect Dis. 2010 Apr;23(2):111-8. PMID: 20075729. [PubMed] [Read by QxMD]

Diamantis SA1, Morrell DS, Burkhart CN. Pediatric infestations. Pediatr Ann. 2009 Jun;38(6):326-32. PMID: 19588676. [PubMed] [Read by QxMD]
Abedin S1, Narang M, Gandhi V, Narang S. Efficacy of permethrin cream and oral ivermectin in treatment of scabies. Indian J Pediatr. 2007 Oct;74(10):915-6. PMID: 17978449. [PubMed] [Read by QxMD]

Hengge UR1, Currie BJ, Jäger G, Lupi O, Schwartz RA. Scabies: a ubiquitous neglected skin disease. Lancet Infect Dis. 2006 Dec;6(12):769-79. PMID: 17123897. [PubMed] [Read by QxMD]

Heukelbach J1, Feldmeier H. Scabies. Lancet. 2006 May 27;367(9524):1767-74. PMID: 16731272. [PubMed] [Read by QxMD]

Raimer SS1. New and emerging therapies in pediatric dermatology. Dermatol Clin. 2000 Jan;18(1):73-8, viii. PMID: 10626113. [PubMed] [Read by QxMD]

Sean Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renown educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

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2 Responses

  1. Alex says:

    Thank you for this information. My doctor doesn’t seem to know anything about this condition and I am in misery trying to deal with this!

  1. January 2, 2016

    […] have covered some specific ones as well (ex, Atopic Dermatitis, Molluscum, Scalded Skin, Measles, Scabies, Popsicle Panniculitis, Meningococcemia, Intertrigo, and Perianal Strep). Now let us review a […]

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