Patients with typical (conventional)
scabies usually have only 10 to 15 live
adult female mites on the body at any
given time. purchase permethrin cream 5%
Usually, only one or two
mites, and frequently none, are
recovered from skin scrapings.
Intense pruritis, usually worse at night,
and a papular rash with or without
burrows occur. The rash and pruritis
result from an immune-mediated
delayed hypersensitivity reaction to the
mite, its eggs, and fecal material.
Areas of the body commonly involved are wrists, finger webs, antecubital fossae,
anterior axillary folds, breasts, waistline, lower abdomen, genitals, and buttocks.
The scalp and face are rarely involved in adults, but may be observed in young
children with scabies.
When diagnosis and
treatment are delayed,
scabies can have an
unusual or atypical
heavy infestation with
hundreds to thousands
of mites. Atypical clinical
presentations are more
debilitated patients, or
those who are immunosuppressed from underlying disease or drug therapy.
When extensive hyperkeratotic skin lesions with crusting and scaling develop,
the infestation is called crusted scabies or hyperkeratotic (formerly
“Norwegian”) scabies. Crusted scabies is highly contagious because
thousands of mites are imbedded in the thick crusts and easily shed in scales
and flakes from affected skin. Crusted scabies is commonly misdiagnosed by
dermatologists, and patients with crusted scabies may develop symptoms of
typical scabies in as little as a few days.
C. EPIDEMIOLOGY OF SCABIES
Transfer of the mite is usually from one person to another by direct skin-toskin
contact. Procedures such as bathing a patient, applying body lotions,
back rubs, or any extensive hands-on contact can provide an opportunity for
mite transmission. Mites may also be transmitted via clothing, bed linen or
other fomites. Fomites play a minor role in situations where the infestation in
the source case is typical scabies; the inanimate environment of patients with
crusted scabies, however, has been shown to be heavily contaminated with
infectious mature and immature mites. In HCF, scabies may be introduced
into the facility by a newly admitted resident with an unrecognized infestation
or by visitors or health care workers as a result of contact with an infested
person in the home or community.
2. Incubation Period
In a previously unexposed healthy individual, the interval between exposure
and the onset of itching is usually 4-6 weeks. In persons who have been
sensitized to the mite by a previous infestation, re-exposure may produce
symptoms in 48 hours or less (owing to prior sensitization to the mite and its
saliva and feces). Following exposure to a source case with crusted scabies
involving extremely large numbers of mites, the incubation period may be
reduced from the usual time of 4-6 weeks to as little as a few days.
3. Period of Communicability
Since the scabies mite is an ectoparasite, an exposed individual is
potentially immediately infectious to others, even in the absence of
symptoms. Cases are communicable from the time of infestation until
mites and eggs are destroyed by treatment.
Definitive diagnosis requires microscopic identification of the mite and/or its eggs
or fecal pellets on specimens collected by skin scraping, biopsy or other means
(Appendix A, “Diagnosis of Scabies by Skin Scraping”). The yield from skin
scrapings is highly dependent on the experience of the operator and the severity of
the infestation. A negative skin scraping from a person with typical scabies
not rule out scabies infestation; mites are easily recovered, however, in skin
scrapings from persons with crusted scabies.
III. SCABIES PREVENTION AND CONTROL PROGRAMS
It is recommended that HCF incorporate a scabies prevention program that involves
all levels of the health care team. The program should include an assessment of
the skin, hair and nail beds of all new admissions as soon as possible following
arrival. Pruritus, rashes and skin lesions should be documented and brought to the
attention of the nursing supervisor and the attending physician for further follow-up.
Essential elements of a successful scabies prevention program include:
1. Written policies and procedures for prevention and control of nosocomial
2. Health care workers who are trained to be suspicious of scabies in themselves
or their patients if unexplained rash or pruritus occurs in themselves or their
patients, and to report such occurrences to their supervisors;
3. A policy to screen newly admitted patients for scabies during the initial
assessment (especially if transferred from another healthcare facility) and any
suspect patient will immediately be placed on contact isolation until examined for scabies
4. A policy that all new employees (especially employees who work at more than
one facility) will be screened for scabies as part of pre-employment screening;
5. Access to and use as needed of the diagnostic skills of a consultant
experienced in recognizing scabies to evaluate difficult or unusual cases or
response to treatment
6. Assurance of adequate support from hospital administration, medical staff,
infection control, employee health and line staff for appropriate evaluation and
treatment of employees, in-house patients and exposed discharged patients
should an outbreak of nosocomial scabies occur.