2. Scabies also known colloquially as the seven-year itch, is a
contagious skin infection caused by the mite Sarcoptes scabiei.
The mite is a tiny, and usually not directly
visible, parasite which burrows under the host's skin, which in
most people causes an intense itching sensation caused by an
allergic response. The infection in animals other than humans
is caused by a different but related mite species, and is
calledsarcoptic mange.
3. • Overcrowding.,Poverty, poor nutritional status.,Homelessness.,Poor
hygiene.
• Institutions. Residential care homes in the UK, refugee camps in some
parts of the world.
• Dementia.,Sexual contact.,Children, especially in developing countries.
• Immune suppression (eg, HIV infection). Like the elderly,
immunocompromised individuals are at particular risk of the crusted
variant. They tend to present with clinically atypical lesions and are often
misdiagnosed, causing a delay in appropriate treatment and increased risk
of a local epidemic.
• The characteristic symptoms of a scabies infection include
intense itching and superficial burrows. The burrow tracks are often linear,
to the point that a neat "line" of four or more closely placed and equally
developed mosquito-like "bites" is almost diagnostic of the disease
RISK FACTORS
4. • Misdiagnosis is common and other skin disorders,
particularly those causing itching, should be
considered, including: Insect bites, Pubic lice and body
lice, Atopic eczema, Tinea, Folliculitis, Impetigo,
Contact dermatitis
• Lichen planus.
• Dermatitis herpetiformis.
• Systemic lupus erythematosus
• Bullous pemphigoid
• Urticaria pigmentosa
• Seborrhoeic dermatitis
• Psoriasis,Prurigo nodularis
DIFFERENTIAL DIAGNOSIS
5. • The diagnosis is largely clinical. A magnifying lens may
help in identification of burrows or even occasionally
mites.--The ink burrow test can be helpful in confirming
burrows. Ink is rubbed over a burrow (for example, with
the surface of a fountain pen nib) then wiped off with an
alcohol swab. Ink will track into a burrow, outlining it.--
The diagnosis can be confirmed by taking a skin scraping
from an affected area, placing the material on a glass
slide with a drop of 10% potassium hydroxide and seeing
an adult mite, egg or eggshell under light microscopy.--
Whilst the sensitivity of skin scrapings is low, it is very
specific and a mite or eggs seen under the microscope
will remove any doubt.
INVESTIGATIONS
6. • The diagnosis is largely clinical. A magnifying lens may
help in identification of burrows or even occasionally
mites.--The ink burrow test can be helpful in confirming
burrows. Ink is rubbed over a burrow (for example, with
the surface of a fountain pen nib) then wiped off with an
alcohol swab. Ink will track into a burrow, outlining it.--
The diagnosis can be confirmed by taking a skin scraping
from an affected area, placing the material on a glass
slide with a drop of 10% potassium hydroxide and seeing
an adult mite, egg or eggshell under light microscopy.--
Whilst the sensitivity of skin scrapings is low, it is very
specific and a mite or eggs seen under the microscope
will remove any doubt.
INVESTIGATIONS