Scabies are caused by the Sarcoptes scabies mite, which is an obligate human parasite, meaning it requires a human host to survive. The mites are tiny, measuring only about 0.3–0.4 millimetres, making them barely visible to the naked eye.

Transmission:

• Direct Skin-to-Skin Contact: The most common mode of transmission is through prolonged direct skin-to-skin contact with an infected person. This often occurs during close personal contact, such as between family members, and sexual partners, or in crowded living conditions like nursing homes or shelters.

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• Fomites: Although less common, scabies can also spread through contact with infested clothing, bedding, or towels, as the mites can survive away from the human body for 24–36 hours under normal conditions.

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• Sexual Contact: Scabies is often classified as a sexually transmitted infection (STI) when it spreads through sexual contact. However, it is important to note that any close physical contact can facilitate transmission, not just sexual activity.

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Symptoms of Scabies

The symptoms of scabies typically appear 2 to 6 weeks after initial infestation in individuals who have never had scabies before. In those who have had scabies before, symptoms may develop within 1 to 4 days due to a quicker immune response.

Common Symptoms:

• Intense Itching (Pruritus): The hallmark symptom of scabies is intense itching, particularly at night. This itching is caused by the body's allergic reaction to the mites, their eggs, and their waste products.

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• Rash: The scabies rash appears as small, red bumps, blisters, or pustules. It often affects areas such as the webs of the fingers, wrists, elbows, armpits, waistline, buttocks, and genitals.

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• Burrows: Burrows are thin, wavy, greyish-white lines on the skin that indicate where the mites have tunnelled under the skin. These are most commonly found in the spaces between the fingers, on the wrists, and on the outer surfaces of the elbows.

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• Crusted Scabies: Also known as Norwegian scabies, this is a severe form of scabies that occurs in individuals with weakened immune systems. It is characterized by thick, crusted areas of skin that contain thousands of mites. Unlike typical scabies, crusted scabies may cause little or no itching but are highly contagious.

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• Secondary Infections: Persistent scratching can lead to breaks in the skin, making it vulnerable to bacterial infections such as impetigo or cellulitis. Symptoms of secondary infection include increased redness, warmth, swelling, and pus formation.