What is Scabies?
Scabies is a parasitic skin infestation by a mite (sarcoptes scabiei) which burrows into the skin and lays eggs.
This common worldwide condition can affect anyone and is spread by skin to skin contact with an infested person. Occasionally it might be spread by contact with clothing, bedding or furniture. The mites can infest these when they fall off a human. This is quite rare as they only survive a short time when not on a human host.
Scabies is prevalent in places like nursing homes, prisons and extended care facilities.
Child care facilities are also a common breeding ground for these infestations. (1)
The symptoms associated with this condition can take some time to appear after the mite has burrowed into the skin. An initial infestation might take anywhere from two to six weeks before the first indications of the condition are seen.
People who have been previously infected with scabies can experience symptoms in as little as one to four days. (2)
This condition can develop anywhere on the body. There are however certain sites the mites favor to burrow, lay eggs and feed. The common places they might be found include:
The skin between the fingers (webbing) and around the fingernails are common places to find scabies mites.
Mites also like the creases in the elbows and wrists and are often found here when a person is infected.
Skin Covered by Jewellery or Clothing
Other places these parasites like to burrow include skin which is covered by a ring, watch or bracelet. They also prefer areas like the buttocks, penis and the skin around the nipples.
Mites very rarely infect skin above the neck on adults, (3)
Children and Scabies
When children are infested with scabies it can be widespread. It can affect any part of the body even the soles of the feet, palms of the hand and scalp. (4)
The symptoms of this condition include:
Severe itching (pruritus) is the most common symptom associated with this condition. It tends to be worse at night, so much so it can interfere with sleep. (5)
A raised bumpy red skin rash can appear on the skin which can be widespread. It’s not always limited to the location where mites have burrowed. The rash is the result of the body’s reaction to this unwanted invader.
A line of spots will appear over the burrow. This can either be red or look like a silvery grey line with a dot at one end.
The rash might resemble hives, little knots under the skin, tiny bites or pimples. (6, 7)
Scratching the rash when it itches can cause it to become infected and produce sores on the skin. (8)
Scabies can sometimes cause an outbreak of eczema. This could be as a result of a reaction by the immune system to the mite infestation. There is potential for the eczema to become infected. (9)
There is a form of scabies called crusted scabies or Norwegian scabies. This tends to appear in people whose immune systems are weak, the elderly or disabled.
When this happens thick crusts are seen on the skin which contain large numbers of both mites and eggs.
These people are highly contagious and can spread the infestation by direct contact or personal items contaminated with mites or crusts.
With crusted scabies, the other symptoms of itching and a rash might sometimes, but not always, be absent. (10)
Scabies mites have a four stage life cycle.
Stage #1 Eggs
The eggs laid are oval in shape measuring about 0.10 to 0.15 millimeters. The female adult will lay two to three eggs per day as she burrows under the skin.
Stage #2 Larvae
Three to four days after the eggs are laid they hatch into larvae. These then move to the skin’s surface and create a new burrow in the outermost layer. The burrows are short and almost invisible and are called molting pouches.
The larvae have six legs at this stage, which lasts about three to four days.
Stage #3 Nymphs
In stage three the larvae shed their skin (molt) and become nymphs. They now have eight legs and look similar to adult mites. The burrow might often be near a hair follicle.
As the nymph grows it molts once more before becoming an adult mite.
Stage #4 Adult Mite
Adult mites are round and straw colored and have no eyes. The females are larger than the males, measuring about 0.30 to 0.45 millimeters. Males are 0.25 to 0.35 millimeters long.
Adult mites mate only once, and this renders the female fertile for her remaining life. Mating happens when a male penetrates the molting pouch occupied by the female mite.
After mating, the female will leave the pouch seeking out a suitable place to make her burrow and lay eggs. She holds onto the skin with sucker like pads on the ends of the front two pairs of legs.
Once in her burrow the female continues to make it longer, laying eggs as she does. This continues the for the rest of her life span which is one to two months.
On average only 10 percent of her eggs will result in adult mites.
Once away from a human host a scabies mite can only survive for 48 to 72 hours. When exposed to temperatures above 50˚C (122˚F) mites die within 10 minutes. (11, 12)
There are some general guidelines regarding the treatment of scabies.
A person who becomes infected might not have any symptoms for between two and six weeks after initial infestation. However, during this time they are still contagious and can spread the condition to others.
In addition to treating the person who is infested, all other family members and any sexual contacts should be treated. This is especially the case where prolonged skin to skin contact might have happened.
All individuals should be treated at the same time, whether they have symptoms or not. This helps prevent potential reinfestation.
All clothing, towels and bedding used by an infested person, their close contacts or sexual partners, also need decontamination. This applies to items used in the three days prior to treatment.
The best way to achieve this is to wash the items and then dry them on the hottest possible settings. Items that cannot be washed should be dry cleaned or sealed in a polythene bag or 72 hours.
We have already mentioned that the mites cannot survive more than about 3 days away from a human host.
It is also advisable to thoroughly vacuum the house, especially carpets and soft furnishings.
The medications used to treat scabies, which kill the mites, are called scabicides.
Available only by prescription these creams and lotions must be applied to all of the body from the neck down. This includes the feet and toes. In the case of infants and young children, the head and neck must be treated as well.
Instructions will be supplied with the medication; it is important to follow them carefully. The medication should be applied when the body is clean, and make sure to put clean clothing on after treatment.
All close contacts should also be examined and treated at the same time.
If you are unsure how to use the medication, consult your doctor or pharmacist.
The itching caused by this infestation is an allergic reaction to the mites and their feces. Itching can still persist for several weeks following treatment, even when all the mites and eggs have been killed.
It may be necessary to repeat treatment if you are still itching after two to four weeks, if you notice new burrows, or if the rash returns.
Any sores you might have as a result of scratching will also be treated with an appropriate medication from your doctor. This will most likely be an antibiotic to treat infection. (13)
What is scabies? Scabies is a parasitic skin infestation by a mite (sarcoptes scabiei) which burrows into the skin and lays eggs.
What are the signs of scabies? Scabies is seen as a red or grey pencil like line under the skin, accompanied by a widespread red, raised itchy rash.
How do you develop scabies? Scabies is contracted from skin to skin contact with an infested person, or occasionally items an infested person has been in contact with.
How are you diagnosed for scabies? Diagnosis will usually be made following observation of the characteristic symptoms. It will generally be confirmed by taking a sample of infested skin for examination under a microscope.
What is the best treatment for scabies? Medications call scabicides are prescribed for this condition.
What are the long term complications of scabies? Scratching the scabies rash can cause infection. This rash can also cause or exacerbate eczema. (14)
Is scabies considered a disability? This infestation is not considered a disability.
Is there a cure for scabies? Medications are available to cure scabies. It is important for all close contacts to be treated at the same time to prevent reinfestation.
Is scabies life threatening? While unpleasant, this is not a life threatening condition.
Scabies is caused by a microscopic mite that burrows under the skin and lays eggs. The immune reaction from the body results in an extremely itchy widespread rash.
Generally contracted by skin to skin contact, this condition can be successfully treated with prescribed medication.
It is important that all close contacts are treated as well, and personal items and homes are thoroughly cleaned to prevent reinfestation.