Scabies
What is scabies and how is it treated? Tips to prevent its spread.
Symptoms and Causes
Human scabies is a disease caused by Sarcoptes scabiei. When this mite infests the skin, it digs small tunnels to lay its eggs. The immune system’s response causes irritation in the affected area.
This contagious disease spreads very quickly through close contact between individuals. It is usually transmitted through skin-to-skin contact but can also spread by sharing towels, bed sheets, or clothing since Sarcoptes scabiei can survive for a few days outside the human body. Therefore, it is common to treat all members of a small community when a case of scabies is detected, even if they show no symptoms.
Despite popular belief, scabies does not only occur in unsanitary environments, although it is more common in enclosed places where many people live together. It often spreads quickly among families living in the same household, daycare groups, or elderly residents in nursing homes. However, scabies stops being contagious 24 hours after treatment begins.
Symptoms
The main symptoms of scabies are:
- Intense itching, typically worse at night in the inflamed areas.
- Sores or wavy burrows in the skin caused by the mites as they move to lay eggs.
- Lumps or small blisters that appear along the sores.
- Vesicles in the folds of the fingers, wrists, arms, legs, or waist.
- Infants and young children often experience generalized exanthema, which consists of a red rash usually accompanied by fever.
Causes
Scabies is caused by a small mite (Sarcoptes scabiei) that, once on the skin, digs burrows to lay its eggs. When the larvae hatch, they move toward the surface. When the body detects their presence, an immune system response or allergic reaction occurs, causing irritation and itching.
The type of mite that causes scabies in humans is different from the one that affects animals, making it impossible for the disease to be transmitted between different species.
Risk Factors
Risk factors for contracting scabies include:
- Direct contact with an affected person.
- Using clothing or belongings that may have the mites on them.
Complications
Complications arise when the affected individual scratches the irritated area, which can lead to a bacterial infection (impetigo) caused by staphylococci or streptococci on the skin.
In rare cases of crusted scabies, caused by a high number of mites on the skin, the disease may be more difficult to treat. Children, the elderly, and people with weakened immune systems are more prone to this. When it occurs, starting treatment as soon as possible is crucial for recovery.
Prevention
When a case of scabies has been detected, the best way to prevent its recurrence or the spread to others is:
- Wash clothing, sheets, and towels that have been used before starting treatment. To kill the mites, use the highest temperature settings for washing and drying.
- For items that cannot be washed, it is recommended to place them in sealed or vacuum bags for one week, so they cannot feed or get air.
- Clean the house thoroughly to remove any remaining mites, infected skin, or scabs.
Diagnosis
Scabies diagnosis is primarily clinical, although certain tests can help confirm or rule out similar conditions.
- Studying the patient’s symptoms and medical history, including lifestyle habits.
- Observing the skin.
- Scraping to take samples for laboratory analysis under a microscope.
- Ink test to visualize the mites in the skin burrows.
Treatment
Treatment for scabies is usually applied to all household members, even those without symptoms, due to its ease of spread. The most commonly used medications are those that kill the mites, available in cream or pill form. The most effective drugs include:
- Sulfur ointment 6-8%: suitable for any patient, typically recommended for nighttime application. Since resistant S. scabiei species have been detected since 2021, this should be considered the first-line treatment.
- Permethrin cream: contains antiparasitic substances to kill the mites. It should be applied to the skin and left for several hours before removal. It is suitable for individuals over two months old but is currently facing multiple resistances.
- Ivermectin: an oral treatment typically prescribed when the cream treatment doesn’t work or to treat patients with weakened immune systems. It currently faces multiple resistances.
