You’re probably familiar with head lice and body lice, but you may not have heard a lot about scabies, scabies mites, crusted scabies or Norwegian scabies. So what is scabies actually? How do you get scabies? Is it contagious? Here is what you should know about this skin condition.

Scabies infestation is one of the reasons a person may experience severe skin itching coupled with a rash. Scabies is a distinct skin condition caused by a parasitic mite (Sarcoptes scabiei var. hominis) and should not be confused with head lice or body lice. Lice are parasitic insects feeding on human blood, while mites feed on the outer layer of skin.

Scabies is a very common skin problem, affecting around 300 million people worldwide. It spreads mainly through skin to skin contact and occurs in all communities, regardless of age, gender, race, social class or personal hygiene habits. Scabies infestation is more common in areas with crowded living conditions such as nursing homes, hospitals, prisons, college dorms and childcare centers.


What Are Scabies Mites?

The mites that cause scabies are eight legged-microscopic parasites related to the spider family. They are grayish white, are less than 0.5 mm long and can seem like a tiny black dot to the naked human eye. A female mite makes tunnels (burrows) into the skin and lays her eggs. These burrows can sometimes be seen on the skin as short s-shaped lines. The female continues to burrow until she dies, in most cases after a month or two.

Within three to ten days the eggs hatch and start maturing. The mature mites travel back to the surface of the skin where they mate and repeat the cycle of tunneling and laying more eggs. Infected people usually have 10 to 15 active mites on their skin.  It is the females’ burrowing movements that cause an allergic reaction and the intense itching associated with scabies, sometimes called ‘the seven year itch’.

How Do You Get Scabies? Is Scabies Contagious?

Scabies is transmitted through close, prolonged skin-to-skin contact. The mites cannot jump or fly but can only crawl and therefore skin-to-skin contact must be long enough to give the mite an opportunity to get from one host to the other.

It is possible for parents and children to infect one another with the mites during the normal course of family life. You should know that scabies is highly contagious. However, scabies cannot be transmitted through a brief hand shake or storing clothes next to someone’s who is infected.




Below is a picture of the life cycle of scabies. After infestation, it can take up to 4 to 6 weeks for scabies symptoms to appear if the person hasn’t had scabies before. If someone had scabies before the symptoms may appear within 2 to 3 days. An infested person can spread scabies even if there are no symptoms present. Humans can’t get scabies from animals, although another type of mite causes a similar disease in animals.

scabies-life-cycle
Picture: CDC – Alexander J. da Silva, PhD/Melanie Moser

What is Norwegian Scabies?

Norwegian (crusted) scabies is a severe form of scabies and was first encountered and described in Norway. It occurs in people with weakened immune systems when scabies mites colonize and infect large areas of skin causing large, crusty red patches that eventually has a wart-like appearance. The elderly, people who are mentally or physically disabled and those with AIDS are at risk to develop Norwegian scabies. The lesions can occur on the hands, feet, elbows and scalp but it may spread over the whole body if left untreated. It is interesting that almost no itching is present in people with Norwegian scabies.

Large colonies of mites are present (usually over two million) causing persons with Norwegian scabies to be much more contagious to others. Because of the large number of mites present, the disease spreads not only through skin-to-skin contact, but also through clothing, bedding and furniture. It should be treated swiftly and aggressively to prevent an outbreak of the disease.

Main Symptoms of Scabies

The main symptoms of scabies are intense itching and a rash on the skin. The itching may be severe and is usually worse at night. Sometimes small s-shaped lines are noticeable where female mites made their burrows in the skin. In children, the rash may be more pronounced due to scratching.

Treatment for Scabies

Scabies can be cured, even though it is highly contagious. There are five main treatment options for scabies and its symptoms:

•    Application of skin creams designed to kill mites;

•    Oral anti-parasite medication;

•    Oral antihistamine to lessen itching;

•    Cortisone cream or oral cortisone for severe itching;

•    Getting rid of scabies mites in the living environment of the affected person.

There are no over the counter medicine available to treat scabies. It is best to consult a medical practitioner if you suspect scabies infestation.


References
Centers for Disease Control and Prevention, Parasites – Scabies
Kids Health, Scabies http://kidshealth.org/parent/infections/skin/scabies.html
Uptodate, Patient Information, Scabies
MedicineNet.com – Scabies Index
Andrews, R.M., J. McCarthy, J.R. Carapetis, and B.J. Currie. “Skin disorders, including pyoderma, scabies, and tinea infections.” Pediatr Clin North Am 56 (2009): 1421-1440.
Heukelbach, J., and H. Feldmeier. “Scabies.” Lancet 367.9524 May 27, 2006: 1767-1774.