Scabies

Scabies: Overview

Scabies is a parasitic skin infestation caused by the tiny mite Sarcoptes scabiei var. hominis. These mites burrow into the skin's outer layer, leading to intense itching, particularly at night, and a red, bumpy rash.

Scabies primarily spreads through close skin contact with an infected person and can affect various parts of the body, including the wrists, fingers, armpits, and groin.

Scabies mites and their Life cycle

Scabies mites burrow into the top layer of the skin, where the adult female lays eggs. The eggs hatch in 3–4 days, developing into adult mites in 1–2 weeks. Allergic reactions to mite proteins and feces in the burrow cause intense itch and rash after 4–6 weeks.

The scabies mite belongs to the Acarina group and has a life cycle consisting of four stages:

1. Eggs: Laid in the skin's outer layer by the adult female.
2. Larvae: Hatch from eggs and have six legs.
3. Nymphs: Molt into eight-legged forms, still maturing.
4. Adults: Mature mites that burrow into the skin to lay eggs, completing the cycle in a few weeks.

How do Scabies mites spread?

Scabies is highly contagious and spreads through prolonged skin contact. Although less common, it can also spread by sharing clothing, towels, or bedding with an infected person.

Although they can survive off the body for a short time, they need the warmth and moisture of human skin and quickly die without it. This means they can't easily move to new people and require direct, prolonged contact for transmission.

Types of scabies

Classic Scabies: This is the most common type, causing intense itching on the hands, wrists, elbows, and between fingers.

Nodular Scabies: This type creates itchy, raised bumps or lumps, especially around private areas, armpits, or the groin.

Crusted Scabies: This is a more serious and highly contagious form of scabies, also known as Norwegian scabies. It creates thick crusts on the skin containing large numbers of mites and eggs.

People with weakened immune systems, like those living with HIV, using certain medications (such as some for rheumatoid arthritis), or undergoing chemotherapy, are more susceptible to developing crusted scabies.

Where do scabies appear the most?

Scabies can occur on various parts of the body, and the common areas where the infestation is often found include:

• Wrists
• Between the fingers
• Folds of the armpit
• Elbow creases
• Groin area
• Nipple
• Penis
• Creases of the buttocks

Most challenging facts about scabies?

Scabies can be problematic for several reasons, and the most challenging aspects include:

Intense Itching: The persistent and intense itching, especially at night, can significantly impact one's quality of life and disrupt sleep.

Contagious Nature: Scabies are highly contagious and easily spread through close personal contact, making it challenging to control outbreaks, especially in crowded environments.

Diagnostic Challenges: Figuring out if you have scabies can be tricky because they look different for everyone and can seem like other skin problems. This might make it take longer to get the right treatment.

Treatment Resistance: In some cases, scabies mites may develop resistance to certain treatments, requiring adjustments in the therapeutic approach.

Impact on Vulnerable Populations: Scabies is more prevalent in low-income tropical areas, affecting vulnerable populations such as children and older individuals. This can make health differences worse and make it harder to fix the problem.

Complications and Secondary Infections: Scratching the itchy rash can lead to open sores, increasing the risk of bacterial infections. In severe cases, complications such as cellulitis or impetigo may occur.

Psychological Impact: Persistent itching and visible skin manifestations can have a psychological toll, causing stress, anxiety, and discomfort for individuals dealing with scabies.

How to prevent Scabies?

Dealing with scabies needs a good plan, like getting the right treatment, and making sure it doesn't spread around too much.

To avoid getting scabies, it's important to keep a few simple steps in mind. First, always wash your hands and stay clean.

• Avoid close skin contact with someone who has scabies.
• Do not share clothing, towels, or bedding with an infected person.
• Wash clothing and bedding in hot water to kill mites.
• Keep your living space clean, including furniture and carpets, to prevent mites from lingering.

Sources

https://www.ncbi.nlm.nih.gov/books/NBK544306/

https://www.who.int/news-room/fact-sheets/detail/scabies

https://www.nhs.uk/conditions/scabies/

https://www.nhsinform.scot/illnesses-and-conditions/skin-hair-and-nails/scabies/

https://www.webmd.com/skin-problems-and-treatments/ss/slideshow-scabies-overview

https://www.nhs.uk/conditions/impetigo/

The mites responsible for causing scabies are tiny parasites (an organism – a parasite that lives

on or inside another organism – the host) smaller than a pinhead, scientifically known as Sarcoptes scabiei var. hominis.

The mites burrow into the outer layer of the skin, where they lay eggs, and trigger an allergic reaction, leading to the characteristic symptoms of intense itching and a rash.

The mites are primarily transmitted through close personal contact (sexual activity) with an infected person, and occasionally through shared clothing, towels, or bedding.

People with scabies usually have around 10-12 adult mites on or in their skin, although some may carry more.

Scabies is easily spread between individuals, but it is not caused by a lack of cleanliness.

In rare cases, a severe form called 'crusted scabies' occurs in individuals with a weakened immune system or those who are elderly and ill. This variant is highly contagious, with thousands of mites on the skin.

It's important to note that scabies in animals are referred to as 'mange,' caused by a different type of mite that cannot live on or in humans.

Scabies medications

For scabies treatment, doctors typically prescribe topical ointments, creams, or lotions, while oral medications may also be prescribed in some cases.

The medication is typically applied at night, as the mites are most active then, maximizing treatment effectiveness.

It's usually necessary to treat the entire body from the neck down, and the medication can be washed off the next morning. This process is often repeated for several days or weeks. Common medications for scabies include:

Derbac M (malathion) lotion. 5% permethrin cream, 25% benzyl benzoate lotion, 10% sulfur ointment, 10% crotamiton cream, and 1% Lindane lotion, Oral ivermectin

PATIENT INFORMATION LEAFLET SCABIES

Advice for Topical Scabies Medication

When using skin treatments for scabies, put the medicine on ALL of your skin, not just the itchy parts. The mites could be anywhere, so covering all areas ensures better treatment. Follow the instructions carefully for effective use.

The most common symptoms include unbearable itching, especially at night when the mites are more active, and the development of small, red, raised bumps. The infestation typically affects areas like fingers, wrists, elbows, and the groin.

It can also make your skin sore and, in rare cases, lead to secondary infections. Doctors treat it with topical creams/lotion or pills.

https://cdn.bad.org.uk/uploads/2021/12/19174008/Scabies-update-PIL-Oct2023.pdfWhen someone is infested with scabies, the symptoms typically develop after an incubation period, which is the time between initial exposure to the mites and the onset of noticeable signs.

If you've had scabies before, the itching usually starts within 1 to 4 days because your body recognizes the mites and reacts quickly.

However, if it's your first time getting scabies, your immune system needs more time—about 2-6 weeks—to react and show symptoms like itching and skin problems.

So, how fast you notice the signs depends on whether your body has dealt with these tiny mites before.

The symptoms of scabies include:

• Intense itching particularly worsened at night.
• Itchy lines (linear burrows) and bumps (papules) on fingers, wrists, arms, legs, and the belt area.
• Inflamed bumps on male genitalia and female breasts.
• Larger rash in infants and small children, appearing on the palms, soles of the feet, ankles, and scalp.
• Typically, most individuals are infected with 10–15 mites.