Your Guide to
Neglected Tropical Diseases

Scabies is a highly contagious skin condition caused by tiny mites that burrow into the skin and lay eggs. The main symptom is intense itching, especially at night, which usually begins 4-6 weeks after the mites first infest the skin. Most people have only 10-15 mites on their body. However, people with weakened immunity may develop keratotic or crusted scabies (also known as Norwegian scabies), a severe, highly contagious form where thick, scaly skin crusts harbor thousands or millions of mites.

Without treatment, scratching can lead to secondary bacterial skin infections that may cause serious complications including kidney disease and heart disease.

Scabies spreads primarily through prolonged direct skin-to-skin contact. This includes activities like holding hands, sleeping in the same bed, caring for children, or sexual contact. The mites cannot fly or jump (they can only crawl), so brief contact rarely transmits scabies. The disease spreads easily within households, schools, and healthcare settings. Transmission can also occur through sharing clothing, towels, or bedding, although this is uncommon with regular scabies.

Crusted scabies spreads much more easily, even through brief contact or contaminated items, because of the extremely high number of mites present. People can transmit scabies even before symptoms appear, during the 4-to-6-week period after infection.

Geographic scope:

• Globally, an estimated 200 million people are affected by scabies at any given time, with 400-600+ million new cases annually.
• Scabies occurs in every country but is particularly common in resource-poor tropical settings.
• Highest prevalence is found in Oceania (including Pacific islands), Latin America, East Asia, and Southeast Asia.

Population affected:

• Children and elderly people are most commonly affected, with the highest burden in children aged 1-4 years.
• Immunocompromised individuals are at higher risk for severe crusted scabies.
• Outbreaks are common in crowded settings such as refugee camps, prisons, hospitals, nursing homes, and disaster relief camps.

Scabies is treated with prescription creams or pills. The most common treatment is 5% permethrin cream applied to the entire body and washed off after 8-14 hours. Oral ivermectin pills are also effective but not recommended during pregnancy or for children who weigh less than 15 kg. Less expensive options include benzyl benzoate and sulfur ointment. However, treatment costs can be difficult for many affected families to afford. WHO has added ivermectin to its Essential Medicines List to improve access. In areas where scabies affects more than 10% of the population, mass drug administration programs provide free community-wide treatment.

Treatment must be repeated after one week because medications do not kill mite eggs. All household members and close contacts should be treated at the same time, even if they have no symptoms. Clothing and bedding should be washed in hot water or sealed in a bag for 3 days. People with crusted scabies need more intensive treatment combining both creams and pills.