Page 109 - JSOM Fall 2019

An Ongoing Series

Scabies

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Elena M. Crecelius, MD *; Mark W. Burnett, MD 2

Introduction
There are few things that make you feel itchy all over more so
than hearing that someone around you has scabies. The mite
Sarcoptes scabiei variety hominis is the cause of this extremely
itchy skin infection. These tiny parasites are present worldwide
but most commonly cause infection in tropical resource-poor
regions. Scabies can occur in people of all socioeconomic lev-
els and ages, with around 130 million people affected at any FIGURE 1 An enlarged
one time. The global prevalence in 2015 was over 200 million view of a Sarcoptes scabiei
var. hominis, which is the
cases, although this is likely an underestimate given the ende- cause of human scabies.
micity of this disease in resource-poor regions.

Background and Clinical Presentation Source: CDC, PHIL, 1975.
https://phil.cdc.gov//PHIL
The S. scabiei var. hominis mites pass from person to person _Images/3810/3810.tif
via prolonged, close contact between those sharing living
spaces or during sexual encounters (Figures 1 and 2). Trans-
mission may occur prior to development of a rash and as long
as the host remains untreated. In the most severe form of the
disease known as crusted, or Norwegian, scabies, transmission
may occur after minimal contact with the host or contact with
the exfoliated skin from the rash. After transmission, the adult
female mites burrow into the new host’s skin to lay their eggs.
After about 10 to 17 days, larvae emerge and eventually ma-
ture into adults which mate and start the cycle all over again.
The mites can live for up to 1 to 2 months on a human host
but only about 3 days on clothing or bedding. If a person is FIGURE 2 Classic rash
exposed to scabies for the first time, the rash usually appears caused by scabies with
4 to 6 weeks after transmission. If a person has been infected macules and papules
with scabies before, the rash usually appears 1 to 4 days after present in the intertriginous
space between the fingers.
exposure.
Scabies is caused by a hypersensitivity response to the mites’
proteins and feces in the skin. This reaction results in an itchy, Source: CDC, Public Health
Image Library, 1977.
reddened rash that can have a varied appearance from flat https://phil.cdc.gov//PHIL_
macules to bumpy papules. Burrows from the mites crawling Images/15381/15381.tif
through the skin may appear as thin, serpiginous lines but
may not be visible if the patient has been scratching their skin.
Milder infection occurs in patients with prior sensitization to
the mites. The rash may persist despite appropriate treatment,
this is most likely due to a prolonged allergic skin reaction.
*Correspondence to elena.m.crecelius.mil@mail.mil
1 CPT Crecelius is a resident physician in pediatrics at Tripler Army Medical Center in Hawaii. She is a graduate of the Indiana University School
of Medicine. COL Burnett is currently chief of pediatrics at Tripler Army Medical Center in Hawaii and is the pediatric subspecialties consultant
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to the US Army surgeon general. He is board certified in pediatrics and pediatric infectious diseases and has served overseas in Korea, Germany,
Kosovo, Iraq, Afghanistan, and Kuwait and as the JSOTF-P surgeon in the Philippines. He is a graduate of the University of Wisconsin-Madison
and the Medical College of Wisconsin.
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