Scabies mite

Scabies is a contagious skin disease caused by an insect called the itch mite (Sarcoptes scabiei).

The tick is transmitted from one person to another through direct contact or through personal items.

[ 1 ], [ 2 ], [ 3 ], [ 4 ]

Structure of the scabies mite

The structure of scabies mites has long been examined using a conventional microscope. Currently, information about the insect has been supplemented by data obtained during microscopic examination using an electronic scanner.

What does a scabies mite look like? The body of this arthropod has four pairs of limbs: two front and two middle-back. The front pairs have many joints, and the outermost of them is equipped with a tubular proboscis with a suction element. At the tip of this joint there are three short claws, with which the mite makes peculiar burrows and scabies passages in obstacles in its path. In the middle between the front limbs is the mouth opening.

The female scabies mite differs from the male by the presence of an elongated flagellate bristle on the back legs. The parasite's body looks like a bean, as it has an oval-oblong shape. On the back there are a large number of needles on both sides of the transverse slit. Females have such a slit on the abdomen: through it, eggs are laid.

The eggs of the scabies mite are oblong and small – their length is approximately 0.2 mm.

The larvae of the scabies mite are white, round, and equipped with three pairs of limbs. It is unlikely that you will be able to see the eggs and larvae of the parasite with the naked eye - they are too small.

The newly hatched young arthropods are also white and round, have four pairs of limbs, and are slightly smaller in size than adults.

Types of scabies mites

The mite that causes scabies is far from the only representative of this type of parasite. There are also species and subspecies of arthropods that can provoke the development of other, no less well-known diseases.

• Sarcoptes scabiei (scabies itch) is a parasite that infects humans, dogs and sometimes cats.
• Notoedres cati parasitizes under the epidermis of dogs, cats and rabbits, but can also pass to humans. It causes the disease notoedrosis.
• The mites Demodex folliculorum and Demodex brevis are the causative agents of human demodicosis.
• Otodectes cynotis is capable of parasitizing only in the ear canal. It dies when it gets on the skin. It causes the disease otodectosis, or ear scabies.

Ticks cannot be identified without examination under a microscope. Only tests can confirm the type of parasite and the type of disease it causes.

Life cycle of the scabies mite

Immediately after the tick attaches to the skin, it begins to make a hole in the stratum corneum of the epidermis: for an hour, the parasite literally “drills” the skin with its claws. The passages of the scabies mite begin with a vertical shaft-shaped hole, continuing further parallel to the skin surface.

The tick moves along the passage at approximately 0.1-5 mm/day, which depends primarily on the speed and activity of the forelimbs.

In total, the parasite can live for about 2 months.

Within a couple of hours after making the first passage, the female begins laying eggs: she can lay up to 3 eggs per day. After 3-4 days from egg laying, larvae emerge, leave the passage and rise to the epidermis layer. After another couple of days, the larvae transform into a nymph by molting, and only after that does the nymph turn into an adult insect. It follows that the general development cycle of the parasite - from egg laying to the emergence of a full-fledged tick - takes approximately two weeks. It should be taken into account, however, that not all eggs are guaranteed to turn into ticks over time: only about 10% of the laid eggs "survive" until this period.

The number of arthropods that can be found on one patient cannot be unlimited. As a rule, parasites do not occupy the entire skin surface, but are localized in certain places: on the hands, in the folds between the fingers.

How does scabies infection occur?

In the vast majority of cases, a person becomes infected through direct contact with another person infected with the scabies mite (provided the external environment is favorable). The main factors that contribute to infection are:

• sexual contact with someone who has scabies;
• failure to respect personal space, lack of personal items (shared towels, shared bed linen and clothing, etc.).

What do you need to know about the features of infection? A tick can survive outside human skin for a relatively short time. Parasites, as well as their larvae, can survive for no more than 2 days at a temperature of +22°C and a relative humidity of 35%. At a higher temperature, the tick dies faster (for example, at +55°C, the insect will die in 10 minutes), and at a lower temperature, it loses its ability to move.

From the above, we can conclude that it is often sufficient to wash clothes and linens at a temperature above +55°C in order to reduce the risk of contracting scabies.

It should be noted that in recent years the incidence of scabies has been approximately equal to the incidence of sexually transmitted diseases, so the risk of infection remains very high.

Symptoms of scabies

The symptoms of the disease caused by the scabies mite are divided into typical and probable (which may be present, but are not mandatory). This happens because each person has a different degree of immune protection. In a patient with a weak immune system, scabies can manifest itself violently, with a rich clinical picture. If the immune system is strong, and the scabies mite has not yet reached a certain degree of maturity, then the symptoms may be scanty.

The incubation period for scabies mite infestation can vary from 2 weeks to 1.5 months for the first infestation, and from four days for re-infestation. A person does not directly feel the bites of the scabies mite: clinically, the disease manifests itself only as the consequences of the parasite's vital activity.

The most typical symptoms are:

• itching of the skin, which intensifies significantly during sleep at night (night is the period of tick activity);
• light gray stripes approximately 6 mm long on the skin, with papular or vesicular elements at the end;
• scratching areas;
• bloody-purulent crusts.

Scabies rashes are small (up to 2 mm), sometimes double. The rash is most often found on the front surface of the body, on the bends of the arms, on the inner surface of the thighs.

In atypical cases, the number of rashes is minimal, itching is mild. The hairline and nail plates may be affected.

Diagnostics

First of all, the patient seeks medical help due to skin itching, which can bother not only him alone, but also members of his family. During the examination, the doctor pays attention to the presence of scabies passages, vesicles, ulcers (papules).

There are also several known specific ways to diagnose the disease.

• To identify the mite, mineral oil is used. A drop of oil is applied to the area where the scabies burrow exits, after which the material together with the mite is examined using a microscope.
• Scrapings for scabies mites can be taken from papular and vesicular elements on the skin surface. In this case, larvae are found in the material.
• Sometimes scrapings are taken from under the patient's nail plates.
• In rare cases, diagnosis is made by trial treatment with anti-scabies agents.

General laboratory tests will be uninformative; only a blood test can determine an increase in the level of eosinophils (a sign of sensitization) and signs of an inflammatory process (in the presence of an infection).

Differential diagnosis is carried out with microbial eczema, or true eczema complicated by secondary infection.

[ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ]

Treatment of scabies

To treat scabies, you can use various means, both traditional medications and folk remedies.

Treatment measures should be applied both to the patient and to the people with whom he/she has been in contact recently. Usually, antiparasitic agents and antiseptics are prescribed to eliminate the disease (if necessary, antihistamine treatment is added).

1. Spregal is an aerosol preparation based on piperonyl butoxide and esdepalletrin. It has an effect almost after the first use. It can be used at any age, even in newborns.
2. Permethrin is an antiparasitic agent that kills ticks and lice. Permethrin is applied at night for 2 days.
3. Ivermectin is a common antiparasitic agent used in both medicine and veterinary medicine. The ointment is used in an amount of no more than 200 mg per kilogram of weight once a week. If the dosage is too high, intoxication is possible.
4. Sulfur ointment is a well-known antiseptic. It is used as a 20% ointment in adult patients and as a 10% ointment in pediatrics. The drug is applied before bedtime for 5 days.

Before choosing a remedy for scabies mites, it is necessary to evaluate some characteristics of the drug. In order for the selected drug to bring the expected effect, it must meet the following parameters:

• destroy not only ticks, but also their eggs;
• does not irritate the skin and does not cause allergies;
• if ingested, it does not have a toxic effect and is easily eliminated from the bloodstream;
• be comfortable to use, not stain skin and clothing, and not have an unpleasant odor.

How to get rid of scabies mites? Many people use folk remedies for this. However, it is necessary to be very careful with such treatment, since many herbal preparations only relieve the symptoms of scabies, without directly affecting the parasite and its larvae. Here are some popular folk recipes:

• Milk mixture: pour gunpowder into sour cream or curdled milk in a ratio of 3:1, put in a warm place for three hours, stirring occasionally. Distribute the mass over the affected areas of clean skin. The effect should appear after 4 procedures.
• Medicinal ointment for scabies mites: mix 1 tbsp. of melted lard, 1 tbsp. of grated laundry soap, 1 tsp. of tar, 2 tsp. of sulfur and apply to the infected areas for a week.
• A remedy made from laundry soap: grate laundry soap, add a little water and place on low heat until smooth. Then add grated onion and a head of garlic. After cooling, you need to mold new soap from the mass and wash yourself with it at night.
• Lavender oil: rub onto body at night.

Some users suggest using the well-known dichlorvos against scabies mites. The preparation is sprayed on the skin surface, avoiding the head area, before going to bed. At the same time, they promise complete relief from the disease in one application. This method can be quite dangerous, since dichlorvos is not intended for such purposes and can cause serious poisoning.

Does a quartz lamp help against scabies mites? Unfortunately, the use of quartz treatment does not affect the vital activity of the mite, and especially not their larvae. Therefore, the use of this method is not advisable. A quartz lamp can only be used to treat the room where the patient is located.

Prevention

The main preventive measure is the detection of scabies outbreaks, the fight against their spread and mandatory treatment of contact persons.

After contact with a patient with scabies, you should visit a doctor and undergo the necessary examination.

If a sick person appears in the family, he should be temporarily separated from other people. His personal belongings, clothes, bed linen, hygiene items should be thoroughly disinfected. Things that cannot be exposed to high temperatures (for example, boiled or ironed) can be treated with the anti-scabies aerosol "A-par".

The question arises: how to treat furniture from scabies mites? Furniture elements can be wiped with a 2-3% soda solution or another disinfectant, paying special attention to handles, armrests and other parts that are most often touched by patients.

It is recommended to wipe the floors indoors every day with a damp cloth using disinfectants.

You should not self-medicate a patient - there are specially trained medical specialists for this.

Forecast

With proper treatment, scabies goes away without a trace.

If the disease is prolonged and left untreated, a person may develop psychological disorders due to constant itching.

Scratches that appear on the skin can be complicated by dermatological problems, such as dermatitis, pyoderma, eczema. In addition, secondary sexually transmitted infections sometimes develop.

The longer the disease lasts and the more complications arise, the more difficult it is to correctly diagnose the pathology. For this reason, experts strongly recommend contacting doctors at the first signs of the disease, without waiting for the condition to worsen.

The scabies mite is not as rare as it seems. Therefore, it is necessary to take all measures to prevent scabies, especially when in contact with strangers and when visiting public places.