Scabies is a very contagious skin disease caused by infestation with a type of microscopic mite called Sarcoptes scabiei var. hominis. The parasite mites responsible for causing scabies can be easily contracted by entering in contact with infested persons. Scabies can also be acquired indirectly, by entering in contact with contaminated objects. Although scabies mites can live for a few days without a human host, recent studies have revealed that scabies is rarely acquired indirectly.

Once they find a human host, scabies mites quickly populate the skin, hiding in less exposed regions of the body. Female mites usually lay their eggs under the fingernails, in the skin folds between the toes or fingers, in the pubic region, in the areas of the buttocks or the upper back, in armpits and the region of the elbows. The first symptoms generated by scabies are skin inflammation, itch and rash. In later stages of the mite infestation, people can also develop skin ulcerations, lesions, blisters, pustules, crust and painful nodules. Most of the symptoms caused by scabies occur due to allergic reactions to the mites' toxic secretions. Persistent skin inflammation and the occurrence of open lesions render people affected by scabies very vulnerable to bacterial or fungal infections. In the absence of an appropriate medical treatment, scabies can lead to serious skin disorders such as impetigo.

Although scabies can be acquired by anyone, the condition is very common among hospitalized patients, especially those who suffer from mental disorders such as dementia. Scabies is very contagious and it can cause serious endemics in overcrowded hospitals, nursing homes and asylums. Due to their limited mobility and their poor self-awareness, debilitating patients in mental institutions are very exposed to acquiring scabies during outbreaks. Malpraxis, neglect and delayed medical assistance during scabies endemics in mental institutions allow the disease to spread among inpatients and medical staff.

In many cases, patients with mental impairment are diagnosed with scabies long after they develop serious complications, rendering the task of overcoming the disease even more difficult. Poor patient monitoring and medical neglect are nowadays thought to be leading factors in causing scabies outbreaks in mental institutions and nursing homes.

In the last decades, scientists have conducted various studies in order to determine the exact causes for the increased incidence of scabies in hospitalized patients with dementia and other mental disorders. Research results have revealed that the high incidence of scabies in mental institutions is caused solely by environmental factors. The conducted studies haven't suggested any physiological relations between mentally impaired patients and the high incidence of scabies among this category of people. Scientists have concluded that people with mental disorders don't present any increased physiological risks in developing scabies.