Scabies: contagion, symptoms and therapy

Scabies is a very contagious skin disease caused by mites (parasites) of the Sarcoptes scabiei hominis type, causing severe itching, red spots and pustules (blisters).


What is a Scabies norvegica?

Scabies norvegica or bark scabies is a severe form of scabies that can occur in some immunocompromised people (with weakened immune systems), the elderly, disabled or weakened people.

People with bark scabies often have grinds on their skin, which contain a large number of mites and their eggs.

People with bark scabies are highly contagious and can easily transmit the infection to other people, both through direct skin contact and through contaminated objects such as clothing, bedding and furniture.

People with bark scabies don’t always have to have the usual signs and symptoms of scabies, such as characteristic rash or itching.
People with bark scabies should receive quick-acting and aggressive medical treatment to cure and prevent outbreaks of scabies.

When do the symptoms of scabies begin after infection?

If a person has never had scabies before, symptoms may appear after up to 4-6 weeks.
One should be aware that an infected person can transmit scabies during this time, even if there are no symptoms yet.
In a person who has had scabies before, symptoms usually appear much earlier, about 1-4 days after contact.

How to get scabies?

The mode of transmission is the direct contact from skin to skin.
Scabies mites are very sensitive to their environment. They can only survive outside a host body for 24-36 hours. Close skin contact between two people is required to transmit the mites. The transmission of scabies can also be done by sharing a bed sheet if someone with scabies was lying there the night before.

Sexual contact is the most common form of transmission in young, sexually active people and scabies are considered by many to be a transmissible STD.
However, other forms of physical contact, such as the hug between mother and child, are sufficient to transmit mites.
Over time, friends and relatives can also get scabies.
School activities usually do not lead to prolonged physical contact, which would be necessary to transmit the mites.

Can you get scabies from a dog or a cat?

Dogs and cats are infested with various types of mites, which, however, do not infect humans.
Animals are not a source of human scabies.
Scabies in dogs are called mange.
When mites from dogs or cats come into contact with human skin, they cannot survive there and only cause a slight itch, which spontaneously disappears.
This disorder is very different from human scabies, which worsens if left untreated.

What are the risk factors for scabies?

Scabies can infect anyone who comes into contact with the mites. The only known risk factor is direct skin contact with someone affected by these mites. The contact arises between people who meet frequently. Transmission at school, on the other hand, is rather unlikely.

Sexual or other close contact (such as a hug) is a prerequisite for the spread of scabies.
The disease occurs in groups, so epidemics can occur within a community.

Symptoms of scabies

Those who suffer from scabies usually have a skin disorder with itching, which worsens until the mites die.

Itching is usually the first symptom.
It often occurs mainly at night or after a bath and is sometimes confused with too dry skin.
The itching is caused by an allergic reaction to the scabies mites.
Often the itching is very pronounced, especially in young children and in the elderly.
The irritated skin often has sores and rashes.
These symptoms are the result of channels (or ducts) that the mites dig into the upper layers of the skin.
Sometimes you can see a small bubble or the mite itself as a small black dot at the end of a canal.
The marks are difficult to see after the surface has been scratched.
Infants may also have just reddened and inflamed skin, sometimes with minor injuries that appear like blisters.

The areas of the body most affected by symptoms are:

  • Between the fingers and on the wrist surface
  • On the outer surfaces of the elbows and under the armpits
  • Around the waist
  • In the navel area
  • On the buttocks
  • Around the nipples, on the bra lines and the breast side
  • On the genitals.

In infants and young children, skin irritation and itching may also occur:

  • On scalp, neck and face
  • On the palms and soles of the feet
  • Often in children, the first symptom occurs in these areas.

Other issues

Skin injuries, so-called secondary skin lesions, can develop in the further course of the disease.

Skin disorders caused by scabies can include:

  • Scratch marks, sometimes covered by grinding. Scratching the mite ducts can irritate and tear the skin.
  • Areas of skin redness, skin dryness, scaling, irritation.
  • Nodular scabies, which are small brownish or reddened raised skin zones (nodules).

The nodules can develop in covered areas, such as the armpits, groin, buttocks, scrotum and penis.
The nodules cause itching and can persist for weeks and months after the scabies have healed.
Children and the elderly are particularly susceptible to these lesions because they are often not treated immediately. The first symptoms in children and the elderly are often confused with other diseases.

Note: Itching and rash in scabies are caused by an allergy (reaction) to the mites (saliva, feces or eggs).
The symptoms of scabies usually begin 2-6 weeks after the actual infection.
Itching and redness can develop in any area of the skin, even far from where the mites are actually located.
That means you can be contagious (that you can transmit scabies) before you know where it is.

How is an infestation with scabies diagnosed?

Diagnosis of scabies is usually made on the basis of the usual aspect, the distribution of the rash and the presence of ducts.
If possible, the diagnosis of scabies should be confirmed each time by identifying mites, mite eggs or mite feces.
This can be done by carefully removing a mite at the end of a duct with a needle tip or by scratching and examining it under the microscope for mites, mite eggs or mite droppings.
One must not forget that a person can be infected even if no mites, mite eggs or feces are found.
Usually, less than 10-15 mites are present all over the body of an affected person who is otherwise healthy. However, people with bark scabies can be infested with thousands of mites and should be considered highly contagious.

Differential diagnosis
Other diseases are sometimes confused with scabies. The scabies mite has a certain similarity with lice and sometimes the therapy of the skin disease is the same.
Scabies can also be confused with bed bug bites.
Unlike scabies, bedbugs are visible to the naked eye and can survive for long periods of time without food.
Sand fleas are fleas that feed on human blood, but unlike scabies, you become infected through contact with plants. Sand fleas also remain on the skin only a few days.
More rarely, rashes and other skin diseases such as tinea (ringworm), herpes zoster (shingles), eczema, dermatitis, allergic reactions (hives) and impetigo (bark lichen) can be confused with scabies.

How long can scabies mites survive?

On a person, scabies mites can survive up to 1-2 months.
Outside a person, the scabies mites survive no more than 48-72 hours. Scabies mites die when exposed to a temperature of 10°C (50°F) for 122 minutes.

Therapy and medication for scabies, guidelines

Treatment of scabies involves killing the mites with medication. There are various creams and lotions. As a rule, a drug is applied from the neck to the feet all over the body and then the cream is left on for at least eight hours.
A second treatment is required if rashes remain or ducts are found again.
Because scabies spreads so easily, the doctor may recommend treatment to all family members and close friends, even if they show no signs of mite infestation.

Medications commonly prescribed for scabies include:

Permetrin 5% (Infectoscab or InfectoPedicul)
The doctor may recommend applying this cream because it contains chemicals that kill the scabies mites and their eggs.
The cream must be applied twice with an interval of about a week.
Permetrin is considered safe in children and adults of all ages, including pregnant or breastfeeding women.

This drug is also a chemical treatment agent, it is available as a cream, lotion and shampoo. This drug is not suitable for children under two years of age, pregnant or lactating women and people with weakened immune systems.

Crotamiton (Eurax)
This medication is applied once a day for two to five days. The doctor may prescribe it to children with scabies.
Even if this drug kills the mites immediately, the itching may persist for a few weeks.

There are scientific studies that testify to the effectiveness of an oil with 10% sulfur in petroleum jelly, which is applied to the affected areas. It is available as an over-the-counter medication and can also be used by pregnant women and in infants.

Sometimes doctors prescribe the oral medication ivermectin (ScabiOral) for people with immunosuppression, for people who have bark scabies, or for people who do not respond to treatment with lotion and cream.

How long does scabies last?

Two one-day treatments are carried out at intervals of one week.
The itching may persist for a while, even if the treatment has removed all the mites.
Normally, the itching passes in 2-3 weeks (sometimes only after six weeks) after elimination of the mites.
Even after completion of therapy, in some cases some brownish-red itchy nodules of up to 2 cm in diameter remain.
These nodules are most commonly found on the genitals and under the armpits.
These blisters are infected, but this does not mean that mites are still present.
In some cases, there is a kind of prolonged skin reaction to the scabies mites.
If nodules form, they usually disappear within three months, rarely they persist up to a year.

When are you contagious?

As long as there are mites or eggs in the skin, you can infect other people.
To be on the safe side, you should wait a few days after the end of treatment. However, if the symptoms persist, you should ask the doctor if a new test may be necessary.

Natural remedies

Itching can persist for a long time after mite-killing drugs are applied.
Some natural therapies can help relieve the itching somewhat.
Cool the skin and immerse in cold water or apply a fresh and damp cloth to the
affected areas to relieve itching.

Apply a soothing lotion.
Calamine lotion is available over the counter and can relieve pain and itching on the skin.

Take antihistamines.
On the advice of the doctor, allergic symptoms caused by mites can be alleviated with over-the-counter antihistamines.

Prevention and prophylaxis

The infection occurs mainly through the handshake.
Since the mites can survive 2-3 days away from human skin, infecting another person is easily possible if they use the same bed or towels.
You should wash clothes, bed linen and towels after each use at a high temperature (above 60°).
To avoid infection in the family, it is necessary to carefully observe the rules of hygiene throughout the house and wrap the mattress with foil before going to bed.

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