What Is Scabies?

Overview

Scabies is an infectious skin condition caused by mites. Although scabies can impact people from any socio-economic background, those who live in poverty or in crowded areas are much more likely to contract it.¹ Even with an estimated 200 million cases each year, most people do not really know exactly what this disease is. It is important to know how this disease presents in order to get treated quickly and protect yourself and the people around you. 

Cause of scabies

Scabies is caused by a parasite known as Sarcoptes scabiei.¹ Sarcoptes is a small insect and a human parasite which depends entirely on its host for survival. These mites penetrate the skin, frequently through your hands, and then disperse throughout the rest of your body.

Due to their size, scabies mites are invisible to the unaided eye. The female mite is bigger than the male and lays eggs after burrowing into the skin.¹ A mite will lay between 40 and 50 eggs during its lifespan. After 3–4 days, the ova develop into larvae, which then mature into adults 10–15 days later.

Mites can attach to your skin via:¹

• Skin-to-skin contact, where a person comes into direct contact with the skin of an infected person
• Contact with a towel, piece of bedding, or upholstered furnishings that has been infested.

Most individuals won't contract scabies from a hug or handshake, as longer periods of skin-to-skin contact are needed for mites to crawl from one individual to another. Notably,  animals with mites cannot transmit scabies to you. Only humans can transmit scabies via skin-to-skin contact.

Types of scabies

There are 3 main types of scabies:²

• Typical mites: The most common cause of scabies. These mites cause itchy rashes on the hands, arms, and other parts of the body. However, the cheeks or scalp are usually unaffected.
• Nodular scabies: Characterised by rashes in the genital region, crotch, or underarm, which may manifest as intense itching, raised bumps, or lumps
• Norwegian scabies: A severe and highly contagious type of scabies. The mites causing Norwegian scabies can survive for up to a week without human interaction thanks to the food and shelter provided by their shed crust. Norwegian scabies is also known as “crusted scabies” due to the thick crusts that develop on the skin of infected individuals.

Signs and symptoms of scabies

The majority of scabies symptoms occur due to the body's immune reaction to the mite's saliva, eggs, or faeces.¹

The symptoms of scabies include:

• Intense itchiness: This is the main symptom of scabies. Itching is typically worse at night and tends to start in one location (often the hands) before spreading to other parts of the body.
• Raised rashes or spots: Usually, a scabies rash will develop right after the itching starts. It usually manifests as a red rash that can develop anywhere on the body. Whilst this rash is obvious on paler skin, it may be harder to see on dark skin. However, they can be felt. Due to how long it takes for the body to respond to mite droppings, it might take 4-6 weeks before the itchiness begins. However, symptoms may appear within 1-2 days of exposure.

Diagnosis of scabies 

Your doctor should be able to identify scabies based on the texture of your skin and by checking for the mite's burrow marks. Sometimes, a diagnosis can be made based on multiple family members exhibiting the same signs and symptoms.

In other cases, dermatoscopy or microscopy can be used. In this, a small sample of the affected skin may be carefully scraped off to be inspected under a microscope for signs of scabies mites, eggs, and faeces.² 

Management and treatment for scabies

If you have scabies and you have never been infected before, visit your doctor right away. Putting off treatment puts yourself and others in danger. Your doctor will need to rule out other serious skin conditions that cause similar symptoms by conducting a few tests. If you are diagnosed with scabies, your healthcare provider will get you started with the treatments. 

The most commonly used treatments for scabies are lotions like permethrin and balms, antihistamines, and steroids, which might also be given to manage the itching and inflammation. Your doctor will be able to give you advice on the best course of action. Cleaning your home's floors and thoroughly vacuuming your carpets and furniture, including your couch and armchairs, are both recommended in cases of crusted scabies.

Whether or not they exhibit any signs, your sexual partner(s) will need to be treated if you have scabies. This is due to the high likelihood that scabies have been spread through intimate physical contact. Avoid having sex and any other close physical contact until you and your partner(s) have finished treatment to lower the risk of reinfection.

FAQs

How can I prevent scabies?

The same measures can be taken to avoid all types of scabies. Avoid getting too close to infected individuals or sharing towels, bedsheets, or clothing with infected individuals. Unfortunately, scabies signs frequently do not appear until a person has been infected for a while, but they can still spread the mites to other individuals.

Even if you aren't yet exhibiting symptoms, it is advised that you get treated for scabies as soon as you learn that you've been exposed to the condition, before the mites have an opportunity to multiply and spread.

Who is at risk of scabies?

Scabies can affect anyone. However, the risk of scabies is higher in the elderly and in those whose immune systems are compromised by illnesses like HIV/AIDS, lymphoma, leukaemia, and organ transplant recipients.

How common is scabies?

Scabies is a prevalent skin disease in developing nations and is estimated that more than 200 million people worldwide are affected at any given moment.¹

With an estimated prevalence of 5–50% in children, scabies occur mostly in areas with poverty and limited healthcare facilities. However, there are also sporadic cases in high-income countries. 

When should I see a doctor?

As soon as you notice the signs and symptoms of scabies or come to know that you've been exposed to the condition, it is important to see a doctor. Even though the disease is not always serious, it needs to be treated properly to prevent it from spreading to people around you.

The scabies mites are rapidly killed by the medication, but the itching may persist for a few weeks. If your skin continues to itch 4 weeks after the end of the treatment, go back to your doctor.

Summary

Scabies is an infectious skin condition caused by Sarcoptes scabies, a species of mite. This small insect depends completely on its host for survival. They penetrate your skin, mostly through your hands, and slowly move throughout the body. The symptoms of the infestation are intense itching and a rash. Scabies can be spread through contact with infected persons or prolonged contact with items used by infected persons. So it is essential to avoid sharing clothes, bedding, etc, if you suspect you or someone you know are infected. Make sure to vacuum and clean the entire house, including the bed and couch, to minimize the spreading of mites. Your healthcare provider will diagnose you to rule out skin infections with similar symptoms. If you are diagnosed with scabies, your healthcare provider will get you started on treatment. It is usually ointments or tablets and resolves within a short period. If you experience itching 4 weeks after your last treatment, visit your healthcare provider again.