Scabies – The Seven-Year Itch

Recommend to others!


Scabies is usually transmitted through close, intimate contact, like sleeping in the same bed or touching a person with scabies; Scabies mites can not fly or jump, they move very slowly. Scabies mites can live up to four days without a human host. Meanwhile, they can be transmitted to other persons through clothing, sheets and other household and personal articles.


Scabies is caused by Sarcoptes scabiei or the itch mite. Mites that cause scabies are attracted to heat and body odor. Female mites enter the skin, digging small tunnels like threads, which are sometimes visible. Parasites lay their eggs in these tunnels.

Mode of transmission

Scabies is usually transmitted through close, intimate contact, like sleeping in the same bed or touching a person with scabies; scabies mites can not fly or jump, they move very slowly. Scabies mites can live up to four days without a human host. Meanwhile, they can be transmitted to other persons through clothing, sheets and other household and personal articles.
Sarcoptes scabiei penetrates the skin very quickly, especially the rough areas or the skin folds (crinkly), such as the elbows, metacarpal joints (finger joints) and knees. Touching and scratching the area infected with scabies can spread the disease to other parts of the body as well. After penetrating the skin, a female mite deposits between 10-25 eggs before dying. Three days later the eggs develop into larvae. These larvae move on the surface of the skin and become adults in 14-17 days. This cycle continues until the mites are killed. Sarcoptes scabies mites that infest man, do not infest dogs or other animals. Similarly, scabies mites transmitted from animals do not survive and do not reproduce in humans. However, they can live long enough in humans in order to cause itchy hives (allergies that cause itch) or produce papules in a few days.
The incubation and contagion period
Scabies is contagious. People with scabies can transmit the parasites to others, before and after the appearance of symptoms, as long as they remain infested and untreated. After the first infestation, several weeks must pass before the appearance of the first symptoms. The patient is contagious during this period which is also known as the incubation period. After a new infestation with sarcoptes scabiei, it will take probably two or three days for the symptoms to develop.


In the case of scabies, the sick person has an itchy and irritated skin, symptoms intensifying until the parasites are killed. Itching (pruritus) – usually appears first. Often it becomes more pronounced at night or after bathing and sometimes it is mistaken for dry skin. Itching is caused by an allergic reaction to the scabies mite. Sometimes the itching is very intense, especially in children and elderly people.
The irritated skin – appears as a rash, and at the level of the sensitive skin area, you can see some small traces like curves. These symptoms occur due to mites which dig tunnels underneath the top layers of the skin. Sometimes you can find a small blister or the parasite itself, which looks like a small black point at the end of the lesion. These traces can be difficult to see after the area was scratched. Infants may have only red and inflamed skin, sometimes with small painful blisters.
The portions of sensitive skin, called secondary lesions, develop later in the evolution of the disease. These lesions include:
- lesions due to scratching, sometimes covered by a crust; the scratch of the lesion can irritate and ulcerate the skin
- areas of red, dry, scaly, irritated skin
- nodular scabies: These lesions are represented by small, elevated, reddish brown areas (nodules); nodules may develop in covered areas that might involve the elbow, between the buttocks, on the scrotum and penis; the nodules are itchy and may persist for weeks or months after the onset of scabies.
Infants and elderly people are especially at increased risk to develop these lesions because they can not be treated immediately. The early symptoms in infants and the elderly are passed unnoticed or are mistaken for other diseases.

Physiopathogenic mechanism

The first infestation
In the case of the first infestation with scabies, itching may miss a few weeks. Meanwhile, the person is contagious, but he does not know that he is a scabies mites carrier. In the first weeks of scabies infestation, the body develops sensitivity to mites, their eggs and to the faeces. Once the body has been sensitized, an allergic reaction is triggered, causing itching. With treatment, scabies mites are killed and itching disappears gradually over several days or weeks. Usually the doctor will decide if it is safe for children to return to school, after the treatment was performed and the drug was completely washed from the skin. The treatment takes between 1-3 days depending on the drug which is used.
If the eggs of the mites are not all killed during the first treatment, they can turn into larvae and cause new symptoms. Without treatment, the parasites multiply and produce more sensitive and itchy. Scabies does not heal by itself. Only forms of scabies transmitted from animals disappear without treatment.
Repeated infestation
In people who have had scabies and are infested again with sarcoptes scabies, itch will appear instantly. The allergic sensitivity developed during the previous exposure triggers an immediate reaction of hypersensitivity to the parasite. Treatment is usually necessary in order to destroy scabies mites and their eggs; Scarcely will an allergic reaction kill the scabies mites.


The most common complication of scabies is represented by the bacterial infection of the skin called impetigo. This occurs most often when scratching the skin intensely. Pilous follicles may also become infected (folliculitis). Antibiotics may be needed in order to treat the bacterial skin infection. The skin may become thickened, red and scaly or shiny, because of the persistent scratching. Rarely, the encrusted (Norwegian) scabies, a severe form of scabies, may develop. Usually, this form of scabies is more common in people with impaired immune systems. For example, some people infected with HIV have developed an extreme infestation with tens of thousands of mites; on the other hand, the infestation is usually limited to 10-15 mites among healthy people.

Consulting a specialist

Consult a doctor if:
- family members suddenly develop itching, mostly nocturnal, which does not disappear in 3-4 days
- severe side-effects occur after using any product in the treatment of scabies
- itching lasts longer than 4 weeks after the treatment finished; after a successful treatment, itching persist for 2-4 weeks, as a result of an allergic reaction to scabies mites previously contacted
- signs of an infection of the skin appear. These include:
- increased pain, turgidity, heat, redness
- sensitive skin
- red streaks extending away from the affected area
- elimination of pus continues
- fever of 37.8 grade C or higher without any cause.

Watchful waiting

Do not expect more than three or four days to seek medical advice if you suspect that you have scabies. The infection and symptoms do not disappear without treatment. The longer you wait until you consult a specialist, the more mites are transmitted to other persons. If a case of scabies is considered to be correlated with a similar disease, spread by the animals (Sarcoptic mange), it is recommended to wait more than a week. The mites that cause this form of scabies can not live on human skin more than a few days, so the human infestation should go away by itself without treatment. However, the animal should be treated by the vet.

Recommended medical specialists

The following categories of healthcare workers can diagnose and treat scabies:
- the staff of the local public health department
- family-doctor or doctor of internal medicine
- pediatrician
- dermatologist.


Usually, the doctor can diagnose scabies if the patient has:
-intense itching, mostly at night (with exacerbation at night)
-skin rash, sometimes accompanied by skin sensitivity; this may appear as tiny curved traces; sometimes you can see small bubbles or a black dot at one end of the lesion; in infants, the lesions generally look like a red, irritated skin, sometimes with small, painful blisters; the doctor will examine the patient’s skin for sensitivity, scratching lesions, ulcerated areas, scabs and red skin which is typical of the infestation with scabies mites.
-other family members or contacts also have itching or have been recently diagnosed with scabies.
Sometimes, one of these tests is necessary in order to confirm the diagnosis:
- skin-scraping: the doctor will take a sample of material from the itchy area by applying a drop of mineral oil or other liquid on the skin, followed by scraping the area with a scalpel; then the sample is examined under the microscope in order to reveal the sarcoptes scabiei, the eggs, the egg box and the faeces of the parasite; this is the most commonly used test in order to diagnose scabies.
- the ink-test: the doctor will drip a washable fluid with the tip of the pen over the damaged area; the surface covered by ink is wiped with a cotton ball soaked in water or alcohol; any present lesion will absorb the ink and it will be seen as a dark line
- skin biopsy / punch biopsy: a sample of skin (punch biopsy or shave biopsy) may be useful in diagnosing diseases that pose problems of diagnosis; skin biopsy is rarely used
- the extraction of the mite using a needle: Rarely, a needle is used in order to extract the mite from its shelter; the mite is placed on a slide and examined under a microscope.

Treatment – Overview

If scabies is suspected, you should address the doctor as soon as possible in order to establish the treatment. Delaying the treatment increases the risk of scabies to be transmitted to other people as well. Scabies does not go away by itself. Scabies can be cured only by using creams and lotions prescribed by your doctor. The drugs which are not prescribed are not strong enough in order to kill the mites. Most creams and lotions are applied to the entire body from neck down. In young children, drugs are applied also to the scalp, face and neck, taking care to avoid the area around the mouth and eyes. The medication is left to act 8-14 hours and then it is washed.
Children can return to kindergarten or school after the treatment was performed completely and creams were washed. The treatment lasts 1-3 days depending on the medication which is used.
Your family doctor may indicate examinations every 2 and 4 weeks after completing the treatment in order to make sure that the scabies was healed. The persistent nodular scabies can be treated by injecting steroids in the nodules. In rare cases, the tar products are applied to the nodules.Itching will persist days or weeks after mites were successfully killed. This itching is caused by a continuous allergic reaction from mite bites. Your doctor may recommend antihistamines (like Benadryl), creams containing corticosteroids and in severe cases, corticosteroid tablets in order to combat itching. The allergic reactions will gradually disappear.
Keep in mind!
Anyone who has had close physical contact with a person infected with scabies should be treated. This includes people who cohabit in the same house, including those who have had direct close and prolonged interpersonal contact (sleeping, bathing or hugs) with the infected persons.


Avoid the close, direct contact (skin-skin) with someone who has scabies, as well as with the personal items of the infected individual; this will help to prevent the responsiveness of scabies. People infected with scabies are encouraged to be cautious, avoiding the transmission of scabies mites to other people.

Home treatment

Everyone in the house, who had close contact in the last months with people infected with scabies, should be treated. This typically includes all the tenants of the apartment, even if they have no symptoms (it may take 4-6 weeks after a person is infected for the symptoms to develop). It is important to disinfect the bed sheets and the clothing of the infected person, in order to kill any mite that might be live, once the prescribed treatment is started.
Over-the-counter drugs for scabies
There is no nonprescription drug which can cure scabies infestation. Nonprescription drugs are not strong enough in order to destroy parasites. If scabies is suspected, do not use nonprescription drugs before consulting the doctor, because the diagnosis of the disease may aggravate.
Over-the-counter drugs for itching
You can use one of these nonprescription drugs in order to combat the itching caused by scabies:
- creams containing corticosteroids (like hydrocortisone cream); this type of medication can cause the scabies lesions look different and so it is difficult for the doctor to diagnose scabies. It is recommended to use the medication only after the doctor examined the patient and diagnosed the disease.
-oral antihistamines (like Benadryl), these drugs do not interfere with the diagnosis or treatment of scabies.


The prescription of Permethrin (Elimite) cream or lotion, is the most common medication used to treat scabies. Unlike the most toxic product called Lindane, Permethrin is considered safe for children less than two months. Only Permethrin, Crotamiton and sulfur-based ointment are considered safe to treat children under two years. Lindane is sometimes used as a secondary treatment option for well-defined groups of people. It must be used only in one application, exactly as it is recommended. Lindane is not recommended to infants, elderly people and persons with weight lower than 49.9 kg or to individuals with impaired immune systems. Lindane shampoo and lotion are not available in all countries for the treatment of lice and scabies. Crusted scabies (Norwegian) – is a rare form, often requiring multiple treatments, sometimes more than one treatment.
The creams containing corticosteroids, antihistamines (like Benadryl) and in severe cases, corticosteroid tablets, can be used in order to combat itching, but they do not destroy sarcoptes scabiei. Persistent nodular scabies may be treated with injections of corticosteroids into the nodules or rarely, with tar products applied to the skin. Most creams or lotions are applied to the entire body from neck down. In young children, the medication is applied also to the scalp, face, neck, taking care to avoid the areas around the mouth or eyes. The drugs usually are allowed to act 8-14 hours and then they are washed. Nonprescription drugs are not strong enough to kill sarcoptes scabiei.
Medication Choices
The recommended drugs used to treat scabies include:
-Permethrin cream 5% (Elimite) – as first treatment for scabies, it usually cures scabies infestation after the first application
-Lindane 1% (Kwell) – it must be used exactly as it is indicated in order to avoid serious adverse effects; lindane is used only for persistent scabies, after trying other drug options or if the patient is unable to use other types of treatment
- Sulfur-based ointment 5% -10% (precipitated sulfur) – an easy and less effective medication than permethrin or lindane medication, it is sometimes used to treat infants and pregnant and breastfeeding women
-Crotamiton 10% (Eurax) – is not frequently used to treat scabies, because it does not always kill all mites and their eggs
-oral ivermectin – present in the United States, the use of ivermectin in order to treat scabies is considered decommissioned; more research is needed in order to confirm the efficacy of the treatment and to determine which individuals would benefit most from this drug; however, the doctor may prescribe it in certain situations, such as in combination with other medicines, in order to treat people with severe scabies. It is necessary to use antibiotics to treat secondary skin infection.
Keep in mind!
When used correctly, lindane is considered a safe and effective treatment for scabies. By its misuse or overuse, lindane can be dangerous and cause permanent impairment of the central nervous system. If your doctor recommends lindane to treat scabies, patients should make sure that they receive, understand and strictly follow the instructions for a proper use.

Treatment failure

The treatment of scabies can fail if:
-medication is not applied correctly; the instructions of the medications used for scabies should be followed accurately
-if the medication did not destroy the mite eggs, when they turn into larvae, a new infestation begins
-when the contacts of an infected person are treated.


Surgery is not indicated for scabies.

Other treatments

Currently, there are no other forms of treatment.



Speak Your Mind


Current day month ye@r *