Leprosy is a chronic contagious bacterial infection that attacks the body's nerves, mucous membranes and skin. The only clear physical symptom is skin lesions, but the disease also causes granulomas on the nerves, resulting in loss of sensation, and in the mucous membranes. If untreated, the disease causes severe disfiguration of the skin, limbs and eyes.
The disease is not easy to treat and requires a multi-drug regimen over a period of at least twelve months, and occasionally for life or a repeated treatment if the disease reoccurs.
However, the disease is also very difficult to contract. Only about 5% of the population appears to be susceptible to it, and infection appears to take prolonged contact with an infected person. Unlike other bacteria, it appears that the actual symptoms are caused by what amounts to an allergic reaction to the bacteria rather than damage caused by the bacteria itself. Moreover, the disease ceases to become contagious within a month of it being treated. Treatment with antibiotics is contraindicated as the death of the bacteria merely increases the body's allergic reaction to it.
Contrary to popular belief, the disease does not cause the loss of body parts. However, the combination of lesions and nerve damage often allow minor wounds to result in a slow deterioration of the tissues.
In Cursed, the patient contracted the disease from his father, who had spent a prolonged period of time in Asia.
In Dying Changes Everything, the patient, who traveled extensively, contracted lepromatous leprosy, which has the effect of making skin actually look younger.