How to identify scabies

Overview

Scabies is a contagious skin infestation caused by a tiny mite known as Sarcoptes scabiei. These mites burrow into the upper layer of the skin to live and lay eggs, leading to an intensely itchy rash. The itching is often the most prominent symptom and is typically worse at night, disrupting sleep. While scabies can affect anyone, it is more common in crowded conditions and close personal contact situations. Prompt identification and treatment are crucial to prevent its spread to others and to alleviate discomfort.

What are the symptoms of scabies?

The hallmark symptom of scabies is intense itching, often described as unbearable and significantly worse at night. This itching can begin several weeks after infestation, as the body's immune system reacts to the mites, their eggs, and their waste products. Other common symptoms include:

• Rash: A pimple-like rash that can appear anywhere on the body, but is most common in specific areas. It may look like small red bumps, hives, or tiny blisters.
• Burrows: These are thin, wavy, raised, and grayish-brown lines on the skin, typically only a few millimeters to a centimeter long. They represent the tunnels the female mites have dug into the skin. Burrows are often difficult to see, especially in crusted scabies, but they are a strong indicator of infestation.
• Sores: Scratching the itchy rash can lead to open sores, which can sometimes become infected with bacteria.

Where does scabies typically appear on the body?

While scabies can affect the entire body, it has preferred locations, especially in adults. In infants and young children, scabies can appear on the head, neck, face, palms of the hands, and soles of the feet. In older children and adults, the rash and burrows are most commonly found in the following areas:

• Between the fingers and toes (finger webs)
• Wrists and forearms
• Elbows
• Armpits
• Waistline
• Buttocks
• Genitals (penis, scrotum, breasts)
• Around the navel

It's important to note that the distribution can vary, and some individuals may have less typical presentations.

How is scabies diagnosed?

Diagnosing scabies can sometimes be challenging, as the symptoms can mimic other skin conditions like eczema or dermatitis. A healthcare provider will typically conduct a physical examination, looking for the characteristic rash and burrows. However, the definitive diagnosis is made by identifying the scabies mite, its eggs, or its feces (scybala) under a microscope. This is usually done by taking a skin scraping from a suspected burrow or rash, placing it on a slide with a drop of mineral oil, and examining it. Other diagnostic tools include dermoscopy (using a magnifying lens) and, in some cases, polymerase chain reaction (PCR) testing for mite DNA.

What is crusted (Norwegian) scabies?

Crusted scabies is a severe and highly contagious form of scabies that primarily affects individuals with weakened immune systems, the elderly, or those with certain disabilities. In crusted scabies, the skin becomes thick, scaly, and crusty, often with widespread lesions and millions of mites. The itching may be less intense than in typical scabies, but the risk of spreading the infestation is significantly higher. Prompt and aggressive treatment is essential for crusted scabies.

When should I see a doctor?

You should consult a healthcare professional if you suspect you have scabies, especially if you experience intense itching that is worse at night, or if you notice a rash that doesn't improve with over-the-counter treatments. Early diagnosis and treatment are vital to prevent the spread of scabies to family members and close contacts, and to avoid secondary bacterial infections from scratching.