Scabies: What it is, How to Recognise its Symptoms and How to Get Rid of it

Scabies (lat. Scabies, also known as the seven-year itch) is a highly infectious parasitic skin disease.

The name of the disease is derived from its main manifestation, i.e. itching.
The word scabies is from Latin: scabere, 'to scratch'.
The cause - the scabies mite or the itch mite - is called Sarcoptes scabiei which means scabby and itchy skin.

It is manifested by the formation of red spots, navels and abrasions on the skin, which significantly itch and force the patient to scratch.
In some cases, the patient scratches the skin to such an extent that it causes extensive wounds.

The causative agent of the symptoms of scabies is the female mite.

The disease is transmitted by direct contact with an infected individual (skin contact, sexual intercourse) or indirect contact with a contaminated object (clothing, blanket, bed linen, towels).

It typically occurs in people with low hygienic standards (more common among certain ethnic Roma communities, or generally people living in extremely poor socioeconomic conditions as well as among the homeless).

We also often encounter this disease in sanitary facilities such as dormitories or other low-standard hostels (hostels for workers, hostels for foreigners).

Worth knowing:
According to the World Health Organization (WHO), the incidence of scabies worldwide is estimated at 300 million cases per year, with the disease on an upward trend.
It affects people of all races and genders, but is most common in children under the age of 15 and in the elderly over the age of 75.
The increase in scabies in the past also occurred during wars or natural disasters, when it was not possible to follow hygienic habits as before.

Scabies has been known since the ancient times

Scabies was also known to our ancestors, and its history dates back to 2500 BC.

The first written mention dates back to 1200 BC, and is also mentioned in the Bible.

Aristotle described it as a skin disease with foci from which small animals climbed, from 384 to 323 BC, but some sources attribute this primacy to the Arab physician Ibn Zuhr.

Scabies was characterized in more detail and named at the time of our era by the Roman physician Aulus Cornelius Celsus.

It was not until 1687 that the Italian physician Giovanni Cosimo Bonomo discovered that scabies was caused by a parasite.

The causative agent of scabies is the obligate parasitic mite of scabies (Latin name: Sarcoptes scabiei var. hominis).
It belongs to the ectoparasites or ectopic parasites of the subclass Acari, the suborder Astigmata and the family Sarcoptidae (arthropod family, small whitish mites).

It attacks and parasitizes human hosts and there are several species of mites that parasitise about 47 other mammals.

In humans, it usually attacks the skin in places where it is most delicate.

What happens in the skin of the infected person?

After attacking a person, it disrupts the protective skin barrier and drills small tunnels in the outermost layer of the skin (epidermis).

Once inside the skin, it survives by absorbing oxygen throughout the body and feeding on the stratum corneum and tissue fluid.

At the blind ends of the superficial layers of the subcutaneous passages, which it closes, the female, which grows to a size of 0.2 to 0.5 mm, lays eggs and continues to reproduce.

The male lives only on the surface of the skin in shallow corridors and dies 2 days after copulation.

The female of the scabies usually lays about 50 eggs, from which new larvae later hatch.

After about two to three weeks, about one-tenth of the larvae hatch as adults.

Adult parasites survive in the human host for 4 to 6 weeks, and are able to create hundreds of new individuals during their short life.

Apart from the living host, they die within about three days. They are especially sensitive to dry, humid, sun or frost.

Worth knowing:
One fertilised female mite is enough to transmit the infection.

How is the disease transmitted?

The disease is transmitted by direct contact with an infected person, less often by indirect contact with contaminated objects.

Longer exposure is also required for this to occur.
A short handshake with a sick person is not enough for transmission, but scabies is still relatively easily transmitted.

Poor hygiene also contributes to the spread of the disease.
Therefore, it most often occurs in people with a low hygienic standard (homeless shelters, Roma communities).

However, it can occur anywhere and with anyone.

Direct transmission of scabies

Infection usually occurs after close physical contact, which lasts longer (hugs, sexual transmission).

The skin is a very slow parasite, so the skin-skin contact must be longer.

Indirect transmission of scabies

Indirect transmission occurs through contaminated objects.

The most common are textiles such as clothing, bed linen, towels and more.

That is why scabies occurs in smaller epidemics in inpatient facilities (sanitary facilities, hostels, camps).

Worth knowing:
Scabies is a highly infectious disease that spreads relatively quickly in certain communities.
It does not disappear spontaneously without adequate treatment.
Each case of the disease is subject to mandatory notification to the regional public health office and subsequent quarantine.
Treatment is necessary not only for the patient, but also for the patient's direct contacts (family, partner, roommate).
Disinfection of the environment and all textiles is also necessary.

Is it possible to get infected from an infected animal?

Many people think that if his pet has been infected with scabies, they can get it too.

The Answer is: NO.

The reason is quite simple.

Scabies in animals (scabies animalis) is caused by mites that are unlike those infecting humans.
Animal bites do not parasitize on the human host.
When in close contact, animal bites can pass to humans, but remain only on the surface of the skin.
Animal bites do not have the ability to settle permanently on human skin and subsequently reproduce.
Animal bites can be removed from the surface of human skin with water and disinfectant.

Worth knowing:
In severe animal disease, the animal's skin can cause local irritation (allergy) on the human body, but it is not an infection of the human host.
Once the animal gets rid of the infections, the local manifestations on the person's skin disappear, too.

After the incubation period of about 2 to 6 weeks, the first symptoms begin to appear.
Their onset and intensity are directly proportional to personal hygiene.
In neglected individuals, they appear earlier.
With recurrent scabies infection, symptoms may appear within 24 hours.
There are confirmed cases in which the disease appeared months to years later.

Manifestations of pruritus are caused by an allergic reaction to mites, i.e. to their proteins.
These proteins are present in the intestines of the skin and come into contact with the host through feces.
Allergy is accompanied by the production of specific IgE antibodies, i.e. symptoms of typical allergic manifestations such as itching or reddening of the skin may persist for some time after healing.

The first signs of scabies

One of the first manifestations of pruritus is itchy skin, which initially occurs only at night.
During sleep, scabies is the most active, at the same time itching is evoked by heat, so it is more pronounced in bed during sleep.

Unpleasant itchy sensations are most common in areas where the skin is softest and warmest.

Typical (predilection) sites of scabies:

• on the hands between the fingers
• on the inside of the wrists
• on the inside of the forearms
• in on the inside of the elbow
• in the armpits
• around the nipples
• around the navel
• in the groin area
• around the genitals
• on the inside of the thigh
• on the inside of the
• on the instep

Worth knowing:
In adults, scabies is not usually found on the face.
The palms and soles are rarely affected.

Itching forces the patient to scratch. Often the sick wake up with scratches on the affected areas.

On closer inspection, it is possible to see pink-gray corridors with a size of 1 mm to 2 cm, which the scabies have drilled.

The tunnels in the skin are erythematous dashed shapes (sometimes resembling the letter S), slightly elevated and at the ends of which the skin can be seen under a thin layer of skin as a darker dot.

In the vicinity of the corridors, reddish skin similar to mosquito bites, which are caused by bites, are present.

Later signs of scabies

Due to very intense itching and subsequent scratching, exematous deposits form on the skin, reminiscent of other forms of dermatitis such as psoriasis or other skin infections.

Scratches form on damaged areas of the skin as with other common injuries.
There are a large number of parasites in the scabs, so a patient with large scabs may be more infectious.

The smaller papules (rash) to reddish papular or vesicular formations are usually present at the ends of the tunnels.

Symptoms of advanced and untreated scabies

In the advanced stage of the disease, when the scabies has multiplied (mainly due to inadequate treatment, or in an untreated individual), extensive eczemas develop.

These dry surface layers of the skin rarely peel off.

Peeling of the skin intensifies itching and scratching, which also worsens scratches, abrasions and wounds on the skin.

Scabies also spreads outside predilection sites (typical sites).

Complications of scabies

Broken skin is a mild source of secondary skin infection.
If another microorganism gets into the wounds, the disease is complicated by inflammation caused by another pathogen.

The infected wound is usually red, hot to the touch and painful.
Pyoderma (purulent skin infections) and purulent pustules (pus-filled deposits) are often present.

Purulent deposits are covered with yellow crusts, which penetrate after the secretion has dried.

Whole-body infection - sepsis is very rare.

Table: Untypical forms of scabies

At first glance, a simple diagnosis based on clinical manifestations is in many cases complex, resp. incorrect.
Scabies is often confused with other itchy dermatoses.
These are mainly diseases from the prurigo group, or allergies.

1. Misdiagnosis usually occurs in patients whose hygienic standard is within normal limits.
2. However, infection can also occur in purebred individuals if they visited a place where they could become infected or were in close contact with an infected person.
3. There are also atypical forms of pruritus that can make diagnosis difficult.

Examination based on clinical picture and anamnesis

Despite the above, the diagnosis is made primarily on the basis of the clinical picture.

At the forefront of the clinic is itching and redness of the skin, scratches on the skin, eczematous deposits, disappearing rashes, or papular formations.

It is also important to visually examine the patient's standard of hygiene and take a targeted medical history focused on the socioeconomic conditions of the patient.

Another important anamnestic aspect is finding out what happened in the pre-disease and where the patient stayed about 6 weeks ago.

Microscopic examination - direct evidence of the parasite

Based on the manifestations of the disease, a professional medical examination is subsequently performed, which consists in proving the presence of the parasite in the skin.

The next step is a biopsy of a part of the skin and subsequent microscopic examination of the deeper layers of the skin, or direct puncture of the parasite from the corridor with the help of a needle.

An experienced doctor can make the correct diagnosis after a microscopic examination of skin scales, where the scabies or its eggs are demonstrably present.

Alarming diagnostic aspects:

• worsening of itching after heating
• similar manifestations in a person in close contact with the patient
• finding corridors with papules arranged in pairs

Table: diseases with which scabies is most often confused

Scabies is caused by infecting a susceptible individual (mammal, human) with a scabies parasite.

The incubation period of pruritus from infection to the onset of the first symptoms is approximately 2 to 6 weeks for the initial infection, and for reinfection (re-infection) the disease may manifest itself after 24 hours.

The first manifestations in the form of pruritus (itchy skin) will appear within a month.

Although the life cycle of the parasite itself is relatively short (14 days), and one would expect the death of the parasite to end the disease, the opposite is true.

The parasite of the skin is then buried under the upper layer of the skin (epidermis), where it forms corridors and lays eggs.  

With this rapid multiplication, the infection stagnates or progresses, never subsiding spontaneously.  
Without treatment, the condition can only get worse.

Extensive scratches cause not only itching but also pain and secondary infection.

However, the prognosis of properly treated disease is very favourable.

Scabies prevention

The most important preventive measure against scabies is to comply with hygiene standards, and therefore it is necessary to pay attention to the principles of personal hygiene.

Hygienic measure in scabies prevention:

• keep regular personal hygiene
• perform hand hygiene frequently
• minimise direct contact with people with a low hygienic standard
• wash and iron personal fabrics (clothes, bed linen...)
• avoid sharing personal items with others
• avoid sharing clothing
• perform hygiene in common areas (hostels, hotels...)