Etzel Cardena and David Gleaves believed the over-representation of DID in North America was the result of increased awareness and training about the condition which had formerly been missing. History
Early references
In the 19th century, "dédoublement", or "double consciousness", the historical precursor to DID, was frequently described as a state of sleepwalking, with scholars hypothesizing that the patients were switching between a normal consciousness and a "somnambulistic state".An intense interest in spiritualism, parapsychology and hypnosis continued throughout the 19th and early 20th centuries, running in parallel with John Lockes views that there was an association of ideas requiring the coexistence of feelings with awareness of the feelings. Hypnosis, which was pioneered in the late 18th century by Franz Mesmer and Armand-Marie Jacques de Chastenet, Marques de Puységur, challenged Lockes association of ideas. Hypnotists reported what they thought were second personalities emerging during hypnosis and wondered how two minds could coexist. In the 19th century, there were a number of reported cases of multiple personalities which Rieber estimated would be close to 100. Epilepsy was seen as a factor in some cases, and discussion of this connection continues into the present era.By the late 19th century, there was a general acceptance that emotionally traumatic experiences could cause long-term disorders which might display a variety of symptoms. These conversion disorders were found to occur in even the most resilient individuals, but with profound effect in someone with emotional instability like Louis Vivet (1863–? ), who had a traumatic experience as a 17-year-old when he encountered a viper.
Sézary disease, or Sézary syndrome, is a type of cutaneous T-cell lymphoma that was first described by Albert Sézary. The affected T cells, known as Sézarys cells or Lutzner cells, have pathological quantities of mucopolysaccharides. Sézary disease is sometimes considered a late stage of mycosis fungoides with lymphadenopathy. Signs and symptoms
Sézary disease and mycosis fungoides are cutaneous T-cell lymphomas having a primary manifestation in the skin. The diseases origin is a peripheral CD4+ T-lymphocyte, although rarer CD8+/CD4- cases have been observed. Epidermotropism (lymphocytes residing in the epidermis)  by neoplastic CD4+ lymphocytes with the formation of Pautriers microabscesses is the hallmark sign of the disease. Although the condition can affect people of all ages, it is commonly diagnosed in adults over age 60. The dominant signs and symptoms of the disease are:

Generalized erythroderma– redness of the skin
Lymphadenopathy – swollen, enlarged lymph nodes
Atypical T cells – malignant lymphocytes known as "Sézary cells" seen in the peripheral blood with typical cerebriform nuclei (brain-shaped, convoluted nuclei)
Hepatosplenomegaly– enlarged liver and spleen
Palmoplantar keratoderma – thickening of the palms of the hands, and soles of the feet

Diagnosis
Those who have Sézary disease often present with skin lesions that do not heal with normal medication. A blood test generally reveals any change in the levels of lymphocytes in the blood, which is often associated with a cutaneous T-cell lymphoma.