Dermatology

Scabies and Lice

A seven year old girl comes to your office with the chief complaint of itching of the scalp. She has no other symptoms and on physical exam there are numerous egg shells on the hair shafts, multiple excoriations on the scalp, and enlarged occipital nodes.

 

What is your diagnosis and how would you proceed?

Fahrenholzia pinnata.JPG
Light micrograph of Fahrenholzia pinnata
https://en.wikipedia.org/wiki/Louse

Head Lice- Pediculosis

Head lice are adult insects that infect the scalp. Transmission is by person-to-person contact and usually presents with scalp itching. Some individuals may have a large infestation without any pruritis. Adult insects may be difficult to locate on the scalp and the diagnosis is usually made by the presence of eggs(nits) on the hair shafts. However, nits found on hair shaft may be indicaative of treated lice and are "empty shells". The adults lay eggs that attach to the hair shafts with the production of a glue substance. Pediculosis is rare in African Americans for unknown reasons. Hair loss may occur if there is secondary pyoderma. Also, secondary bacterial infection may lead to enlarged occipital and cervical lymph nodes.

Transmission is by contact with an infected head.  Lice do not live long on fomites.  Children should not sharae combs and hats. 

Much of the management concerning head lice deals with prevention of spread.  Adults and children who live with a person diagnosed with pediculosis should be tested and treated if necessary. School no nit policies should be challenged becasue the presence of nits does not mean there is an active infection and the child has been infected and in school for a long period of time before diagnosis. 


https://en.wikipedia.org/wiki/Louse

Treatment

  1. 1% Permethrin rinse (Nix) and Pyrtherin (Rid) are the first line treatments. Do not use conditioners or shampoo prior to use becasue may decrease effectiveness of treatment.  do not shampoo for 48 hours after treatment.   Requires retreatment 7-10 days later because they are not ovicidal. Both are OTC and inexpensive. There are reports of resistance.
  2. If treatment failure, Malathion (Ovide) has excellent safety profile in children > 2 y.o. and with increased resistance of lice, may be first the choice. Expensive and requires a prescription. 8-12 hour application time.
  3. Failure to eradicate lice in children <2 would treat with  5% Benzyl alcohol, (Ulesfia).  Requires 2 applications 1 week apart.
  4. Oral ivermectin is a new treatment for previous failures.  Not FDA approved for treatment of lice.
  5. Topical Ivermectin (Sklice) approved by FDA 2012
  6. Lindane- not used in children.
  7. Spinosad (Natroba)- >4 y.o. Very expensive
  8. Carefully wash all bedclothes and brushes and combs
  9. Lice do not live long on fomites
  10. Nits are very tenacious and difficult to remove from hair shafts. After treatment, they are not able to transmit the infection although schools are often unwilling to allow children to return to school while nits are present. Combing with a fine tooth comb and going from outside toward the scalp may facilitate removal. Rinsing with a 1:1 vinegar to water rinse may be helpful.  Educating schools is very important to allow children to get back to school.
  11. Butter, olive oil, mayonnaise, and petroleum jelly have also been found efficacious to smother the lice and suffocate them.
  12. Parental reassurance. Some parents may get "neurotic" after their child is diagnosed with head lice and go on a wild cleaning spree of both the environment and the child's hair.
  13. Treatment of family members without infection usually is not indicated.

Scabies

Infection by the mite Sarcoptis scabiei leads to scabies. The infection is transmitted by contact with infected individuals. All ages are vulnerable. Debilitated and immunodeficient may have more severe cases. Animal scabies are not able to live on human hosts although they may cause rashes.  Animals, mostly dogs and cats, can also carry scabies.  The mites may live up to 48 hours on fomites. 

Life cycle-female burrows under the skin to superficial layer where she lays eggs (3/day up to 10-25 total) and deposits fecal material. The larva mature over 3-4 weeks and then make way to the surface where the adults mate and the males die and the females burrow again Adults can not live off body for longer than 2-3 days. Scabies is unusual in African Americans.


https://en.wikipedia.org/wiki/Scabies

Clinical Presentation

Usually presents with rash and severe itching due to a delayed type IV hypersensitivity reaction to the mite, mite feces, and mite eggs.  Itching is sometimes more severe at nighht.  In older individuals lesions are unusual above the neck. Children less than three and infants may have lesions on the face and scalp as well as involvement of the palms and sole with pustules and vesicles. There may be papules, nodules, scaling, evidence of severe itching, and secondary bacterial infection. Urticarial lesions may present after treatment, this hypersensitivity reaction does not indicate inadequate treatment. Will disappear without treatment, but may take months. 

Diagnosis

  1. think of scabies when patients present with severe pruritis, extensive rash, and positive history of someone with rash and pruruitis.
  2. Distribution on the webbed areas of the hands and feet and absence of lesions on the face, make the diagnosis likely. 
  3. The characteristic burrows may be found, but often are not present or difficult to locate. 
  4. Scrapping with scalpel demonstrating mites and scybala on a slide clinches the diagnosis. 

Treatment

  1. Treat all family members even if other members are asymptomatic. (30g/each adult)
  2. 5% Permethrin (Elimite). This is a single application that has a 90-95% cure rate. Don't use in less than 2 month olds. Apply thoroughly to skin from neck to solees of the feet, including nails.  May repeat in 7 days
  3. Lindane lotion. Some concern in causing seizures.  Not used presently
  4. Crotamition
  5. After treatment there may be continued itchingsecondary to allergic reaction to antigens and should advise patients of this possibility. May treat with oral antihistamines and topical steroids.
  6. Wash clothes and bed linens in hot water.  Place shoes and other non-washable items in air tight plastic bags for 3 days.
  7. PO Invermectin in difficult cases.  First line for crusted scabies.

References

  1. Reeves, J. Head Lice and Scabies in Children. Pediatric Infectious Disease Journal June 1987 Vol 6 No. 6
  2. Rasmussen, James. Scabies Pediatric in Review March 1994
  3. Williams Keoki, Reichert Amanda, MacKenzie William, Hightower Allen, and Blake Paul Lice, Nits, and School Policy Pediatrics, Vol 107 No. 5 May 2001
  4. Morgan-Glenn Patricia.  Scabies.  Pediatrics in Review September 2001
  5. Roberts,Richard Head Lice New England Journal of Medicine Vol 346 No. 21 May 23, 2002
  6. Pearlman D. A Simple Treatment For Head Lice: Dry-on, Suffocation- Based Pediculicide. Pediatrics Electronic pages September 2004.
  7. Chosidow O Scabies.  N Engl J Med April 20, 2006
  8. Lebwohl M. et al.  Therapy for Head Lice Based on Life Cycle, Resistance, and Safety Considerations.  Pediatarics May 2007
  9. Currie BJ, McCarthy JS. Permethrin and Ivermectin for Scabies.  New England Journal of Medicine  Feb 25, 2010.
  10. Chosidow O et al. Oral Ivermectin versus Malathion Lotion for Difficult to Treat Lice.  NEJM March 11, 2010
  11. American Academy of Pediatrics Head Lice Pediatrics August 2010
  12. Goates et al.  An Effective Nonchemical Treatment for Head Lice:  A Lot of Hot Air.  Pediatrics 2006; 118;1962
  13. Frankowski B et al. Head Lice.  Pediatrics 2010
  14. golant A and Levitt J. Scabies- A Review of Diagnosis and Management Based on Mite Biology. Pediatrics in Review January 2012
  15. Pariser D et al.  Topical 0.5% Ivermectin Lotion for Treatment of Head Lice.  New England Journal of Medicine Nov 1, 2012