This disease can affect people at any age, but it is more common in young people and the elderly.

Ticks that cause ulcers are tiny parasites, smaller than a pinhead. They are usually spread through direct skin-to-skin contact with someone who already has an ulcer and sometimes, but rarely, through shared clothing, towels, or bedding. Scars on pets are caused by a different type of tick and therefore cannot infect humans. People with ulcers have an average of about a dozen adult mites on their skin
This very small creature causes an allergic reaction by burrowing into the human skin. The severe itching caused by infection is often so uncomfortable that it prevents a person from sleeping at night.