Scabies is an infestation of the skin by the human itch mite, known scientifically as Sarcoptes scabiei var. hominis. This mite is a tiny, eight-legged parasite that is too small to be seen with the naked eye. The infestation begins when a fertilized female mite burrows into the upper layer of the skin, creating a tunnel where she lives and deposits her eggs.

The intense itching and pimple-like rash associated with scabies are not caused by the mites biting, but rather by the body’s allergic reaction to the mites themselves, their eggs, and their waste products (feces). For a person who has never had scabies before, this allergic reaction can take four to six weeks to develop after the initial infestation. For someone who has had scabies in the past, the immune system recognizes the invader much more quickly, and symptoms can appear within just a few days.

There are two main types of scabies:

• Classic Scabies: This is the most common form. An infected individual typically has only a small number of mites on their body, usually around 10 to 15. The rash and itching can be widespread due to the body’s allergic response.
• Crusted Scabies (formerly Norwegian Scabies): This is a much rarer and more severe form of the infestation. It occurs primarily in individuals who have a weakened immune system (such as the elderly, those with HIV/AIDS, or organ transplant recipients) or who are otherwise debilitated. In crusted scabies, the immune system is unable to control the mites, allowing them to multiply into the thousands or even millions. This results in the formation of thick, crusty patches on the skin that are teeming with mites and are extremely contagious.

In my experience, nighttime itching, especially if multiple family members have it, is the strongest red flag. Once one person in a household gets it, others usually follow unless treated quickly.

Scabies is caused by the infestation with the microscopic human itch mite, Sarcoptes scabiei var. hominis. The mite’s life cycle takes place entirely on and within human skin.

1. Burrowing: After mating, the adult female mite burrows into the epidermis (the top layer of skin), creating a characteristic S-shaped tunnel.
2. Egg Laying: She lays two to three eggs per day inside this burrow for the duration of her one- to two-month lifespan.
3. Hatching: The eggs hatch in three to four days, releasing larvae.
4. Maturation: The larvae mature into adult mites on the surface of the skin over a period of about one to two weeks, after which the cycle repeats.

As mentioned, the primary symptoms of itching and a rash are caused by a delayed hypersensitivity reaction of the body’s immune system to the proteins and waste products of the mites and their eggs.

I often explain to patients that it’s not the mites you feel, it’s your body’s reaction to them. This is why symptoms can start weeks after infestation and why even a few mites can cause severe itching.

Scabies is a highly contagious condition that is transmitted from person to person. It spreads easily in settings where people are in close physical contact.

Direct Skin-to-Skin Contact

This is the most common mode of transmission. The infestation is typically transmitted through prolonged, direct contact with an infected person’s skin.

• A quick handshake or a brief hug is usually not enough to spread the mites.
• The type of extended contact needed often occurs between family members living in the same household (e.g., sleeping in the same bed) or through sexual contact.

Transmission via Fomites (Contaminated Items)

While less common for classic scabies, it is possible to get infested by sharing personal items with someone who has scabies.

• This can include sharing clothing, towels, or bedding.
• This mode of transmission is a much greater risk for the hyper-contagious crusted scabies. Thick crust from the skin is filled with thousands of live mites.

Crowded Environments

Because it spreads so easily through close contact, scabies outbreaks are common in crowded settings where people are in close proximity for extended periods. This includes:

• Nursing homes and long-term care facilities.
• Childcare centers and schools.
• Prisons and other institutional settings.

It is important to remember that animals do not spread human scabies. Pets can get a different type of mite infection called mange, but the mite that causes human scabies cannot survive and reproduce on animals.

I always ask if others in the household have similar symptoms. Scabies loves company, it rarely affects just one person in close-contact settings like families or dorms.

The signs and symptoms of scabies are driven by the body’s allergic reaction to the burrowing mites.

The two hallmark symptoms are:

1. Intense Itching (Pruritus): This is the primary and most distressing symptom. The itching is often severe, relentless, and is characteristically worse at night, frequently disrupting sleep.
2. A Pimple-Like Rash: The rash typically consists of small, red bumps (papules) that can look like tiny pimples, hives, or small blisters.

Besides the rash, a key diagnostic sign that a doctor may look for is the burrow.

• A burrow is the small, thread-like tunnel created by the female mite. It may appear as a tiny, grayish-white or skin-colored line on the surface of the skin, often only a few millimeters to a centimeter long. Burrows can be very difficult to see with the naked eye, as they are often obscured by scratching.

Classic Locations

The scabies mite prefers to burrow in specific areas of the body. The rash and burrows are most commonly found in the following locations:

• The webbing between the fingers.
• Wrist, elbow and knee creases.
• The armpits.
• The waistline or belt line.
• Around the nipples in women.
• On the buttocks and genital area.
• In infants and very young children, the infestation can be more widespread and may also affect the face, scalp, palms of the hands, and soles of the feet.

When someone tells me they itch more at night and the rash is in webbed areas between fingers or around the waist, I strongly suspect scabies. Often, one look at the burrows confirms it.

While the symptoms of intense nighttime itching and a rash in the classic locations are highly suggestive of scabies, a definitive diagnosis is important to ensure proper treatment.

• Clinical Diagnosis: In many cases, a doctor or dermatologist can make a diagnosis based on a physical examination of the rash and a detailed history, especially if other household members are also itching.
• Skin Scraping: The most definitive way to diagnose scabies is to perform a skin scraping. A doctor will use a scalpel blade to gently scrape a burrow or an un-scratched papule. The scrapped material is placed on a microscope slide with a drop of mineral oil. When examined under the microscope, the presence of a mite, its eggs, or its fecal pellets (known as scybala) confirms the diagnosis.
• Dermoscopy: A doctor may use a dermatoscope (a special handheld magnifying device) to look for the “delta-wing” sign, which is the triangular shape of the mite’s head visible at the end of a burrow.

You don’t always need a microscope. In many cases, the history, itch and rash are enough. But in unclear cases, I prefer doing a quick skin scraping to confirm.

Scabies treatment involves killing the mites and addressing symptoms and reinfection risk.

The Most Important Principle: Treat Everyone at Once

 Because scabies is so contagious, a critical part of successful treatment is that all household members and any other close contacts (including sexual partners) of the infected person must be treated at the same time, even if they do not have any symptoms. Failure to treat all contacts simultaneously is the most common reason for treatment failure and re-infestation.

1. Scabicide Medications

• Permethrin 5% Cream: This is the gold standard and first-line treatment for scabies worldwide (CDC, 2024). It is highly effective and is safe for use in adults, children, and infants older than 2 months. The cream must be applied meticulously to the entire body, from the neck down to the soles of the feet. It is left on for 8 to 14 hours (typically overnight) and then thoroughly washed off. In infants and the elderly, the scalp and face may also need to be treated.
• Oral Ivermectin: This is an oral anti-parasitic medication that is an effective alternative. It is often used for crusted scabies (where topical cream application is difficult) or in institutional outbreaks.

2. Environmental Decontamination

On the day that treatment is started, it is also necessary to decontaminate the immediate environment to kill any mites that may have fallen off the body.

• All bedding, clothing, and towels used by the infested person in the three days prior to treatment should be machine washed in hot water and dried on a high heat setting.
• Items that cannot be washed should be removed from body contact and sealed in a plastic bag for at least 72 hours. Scabies mites cannot survive for more than 2 to 3 days away from human skin.

3. Managing the Post-Scabetic Itch

 A crucial point for patients to understand is that even after successful treatment has killed all the mites and their eggs, the itching can persist for another two to four weeks. This is not a sign of treatment failure or re-infestation. It is due to the body’s ongoing allergic reaction to the dead mites and their debris that are still embedded in the skin. A doctor may recommend over-the-counter antihistamine pills or a topical corticosteroid cream to help manage this lingering itch.

I always remind patients to treat their whole household, even if they feel fine. Scabies is a team problem, and unless everyone is treated together, it’ll just keep coming back.

Scabies is a common and intensely uncomfortable skin infestation that can affect anyone, regardless of their personal hygiene. It is caused by the microscopic human itch mite and is characterized by a relentless itch that is worse at night. The key to successful eradication is a comprehensive and diligent approach. This includes a proper diagnosis from a healthcare provider, the correct application of a prescription scabicide cream, the simultaneous treatment of all family members and close contacts, and the decontamination of bedding and clothing. While the experience can be distressing, it is important to remember that scabies is a fully curable condition.

Centers for Disease Control and Prevention (CDC). (2024). Parasites – Scabies. Retrieved from https://www.cdc.gov/parasites/scabies/index.html

American Academy of Dermatology (AAD). (n.d.). Scabies: Overview. Retrieved from https://www.aad.org/public/diseases/a-z/scabies-overview

World Health Organization (WHO). (2023). Scabies. Retrieved from https://www.who.int/news-room/fact-sheets/detail/scabies