Scabies

Scabies

Scabies (Sarcoptes scabiei), also known as the human “itch mite” is an eight-legged microscopic mite that burrows into the epidermis of the skin, where it lives and lays its eggs. Scabies can occur anywhere in the world and affects people of all races and social classes. Scabies spreads very rapidly under crowded conditions where close body contact is frequent. Such places as nursing homes, extended-care facilities, and prisons are often sites of scabies outbreaks. (CDC, 2010)
Close physical contact and, less often, sharing clothing or bedding with an infected person can spread the mites. Once the scabies mite comes into contact with a host the female mite then burrows just beneath your skin and produces a tunnel in which she deposits her eggs. The eggs will then hatch within three to four days, and the scabies mite larvae will then work their way to the surface of the infected host’s skin. When they reach the host’s skin they will mature and spread to other areas of the host’s skin or to the skin of other people. The intense itching produced by the scabies mite are the results of an allergic reaction of your body to the mites, eggs and/or their waste. (Mayo Clinic, 2012)
Dogs, cats and humans all are affected by their own distinct species of mite. Each species of mite prefers one specific type of host and doesn't live long away from that preferred host. So humans may have a temporary skin reaction from contact with the animal scabies mite, but people are unlikely to develop full-blown scabies from this source, as they might from contact with the human scabies mite. (Mayo Clinic, 2012)

According to the May Clinic (2012) scabies causes severe itching that often becomes worse at night, and thin irregular burrow tracks can be seen on the skin. The burrow marks appear as tiny blisters or bumps and typically appear in folds of your skin. Although almost any part of your body can be infected, in adults scabies is most often found in the following locations: * Between the fingers * In the armpits * Around your waist * Along the insides of wrists * On your inner elbow * On the soles of your feet * Around the breasts * Around the male genital area * On the buttocks * On the knees * On the shoulder blades
The head, face, neck, palms of the hands, and soles of the feet often are involved in infants and very young children, but usually not adults and older children. Evidence of an infestation will vary depending on incidences of previous infection.
The amount of time that it takes for a host to exhibit signs and symptoms is dependent upon whether the infected host has ever has a scabies infection before. If the host is infested with scabies mites the first time, symptoms do not usually appear for up to two months (2-6 weeks) after being infested. If the infested person has had scabies before, symptoms will appear much sooner (usually within 1 to 4 days) after being exposed to the scabies mite. An infested person can still transmit scabies, even if they do not have signs and symptoms, until they are successfully treated and the mites and eggs are destroyed.
Even though scabies is not considered to be serious, it can lead to serious complications as a result of the infestation. When infested with scabies the host will experience intense itching that can lead to scratching, that can then lead to skin sores. These sores sometimes become infected with bacteria on the skin, such as Staphylococcus aureus or beta-hemolytic streptococci. Sometimes the bacterial skin infection can then lead an inflammation of the kidneys called post-streptococcal glomerulonephritis (Mayo Clinic, 2012).
If scabies is left untreated or infests an immunosuppressed patient it can become severe. Once it becomes severe it is called crusted scabies, and is much harder to treat. It can affect the elderly, people who have a compromised immune system, or who have conditions that prevent them from itching and/or scratching (spinal cord injury, paralysis, loss of sensation, mental debility). Common signs of crusted scabies are widespread crusts on the skin, that tend to be thick, crumble easily when touched, and look grayish in color. Sometimes the crusts appear on one or more areas of the body such as the scalp, back, or feet (American Academy of Dermatology, 2013). Crusted scabies are characterized by pimple like bumps and thick crusts that look similar to scabs over the skin, and they can contain many mites. The itching that is usually present in scabies infestation may be absent in crusted scabies because of a patient’s altered immune status or neurological condition. Because the host is infested with large numbers of mites (many times up to 2 million), people who are infested with crusted scabies are extremely contagious. Persons with crusted scabies may not show the usual signs and symptoms of scabies such as the characteristic rash or itching (CDC, 2010).
Diagnosing scabies is relatively easy. The physician looks at the patient’s skin, and locates a site of suspected infestation. Once the location is identified as having a possible scabies infestation the physician will then take a skin scraping of the area. He will then look at the sample under a microscope. Evidence of larvae, eggs, waste or an actual mite will prove infestation, and treatment can commence (Mayo Clinic, 2012).
There are a few different topical medications that can be used to treat scabies, all of them come in the form of either a lotion, cream or shampoo. Permethrin 5 percent is the most common medication that is used, as it is relatively safe for use on children and pregnant or lactating women. According to the Davis Drug Guide (2013) Permethrin 5 percent should be left on the skin for 8 to 14 hours after application and then washed off. The desired outcome is for the scabies mite, eggs and larvae to be eliminated after one application of this medication. In severe cases more than one application may be required to achieve the desired effects. Steps should be taken to prevent re-infestation of scabies.
The patient should be instructed on the proper methods of preventing re-infestation, which include washing all clothes, including outdoor apparel and household linens. This should be done by machine-washing using very hot water and dried for at least 20 min in a hot dryer. Dry-cleaning non-washable clothes, and the brushes and combs should be soaked in hot, soapy water for 5 to 10 minutes. The temperature of the water should reach at least 130°F in order to kill all scabies mites that are present on the brushes and combs. The patient should be reminded that brushes and combs should not be shared with other people. Wigs and hairpieces should be shampooed as well, and rugs and upholstered furniture should be vacuumed as soon as possible. Toys should also be washed in hot, soapy water. Items that cannot be washed should be sealed in a plastic bag for 2 weeks (Davis Drug Guide, 2013).

References

CDC. (2010). Retrieved from: http://www.cdc.gov/parasites/scabies/
The Mayo Clinic. (2012). Retrieved from: http://www.mayoclinic.com/health/scabies/DS00451
American Academy of Dermatology. (2013). Scabies: Signs and symptoms. Retrieved from: http://aad.org/dermatology-a-to-z/diseases-and-treatments/q---t/scabies/signs-symptoms
Davis Drug Guide. (2013). Retrieved from: http://www.drugguide.com/ddo/ub/view/Davis-Drug-Guide/51599/all/permethrin?q=Permethrin

*