Progression and diagnosis

Once infection has occurred, the bacillus multiplies very slowly and the incubation period is often in excess of 5 years. It can take as long as 20 years for symptoms of leprosy to appear. Reaching a correct diagnosis of leprosy can also be delayed, especially in countries where the disease is now very rare and awareness of its clinical presentation among the medical profession is low. Stigma can also delay presentation. However, it is important for patients to be diagnosed as soon as possible and started on drug treatment in order to prevent permanent damage and disability.

Leprosy usually starts as loss of sensation (anaesthesia) in a lighter coloured (hypopigmented) skin lesion that can occur anywhere on the body. Nerves and joints in proximity to these skin lesions become swollen when affected. The spectrum of disease which then develops is determined by the degree of cell-mediated immune response mounted by the host and is classified as follows:-

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In the majority of patients, the disease progresses without deformity or other serious effects. In a few patients, the involved nerves become damaged leading to loss of sensation and function with increased risk of trauma and infection, reduced circulation and muscle loss, and ultimately limb deformity and disability. However, with early detection and correct treatment leprosy is a curable disease.

• Leprosy - Notifying a case of leprosy
  Leprosy became a notifiable disease in England & Wales in 1951. A register of all leprosy cases is held at the Health Protection Agency Centre for Infections. The notification process is summarised on this page.
  Added/updated: 18 February 2010
  
• Leprosy - Global situation
  The introduction of multidrug therapy (MDT) in 1981, and its consequent almost universal adoption, has dramatically reduced the total number of patients on treatment at any one time. At the beginning of 2008, the global registered prevalence of leprosy was 212,802 cases, compared to 5.2 million in 1985.
  Added/updated: 18 February 2010
  
• Memorandum on Leprosy (PDF, 700 KB)
  Department of Health and the Welsh Office - Memorandum on Leprosy, August 1997. These guidance notes contain information on: the natural history and epidemiology of leprosy; presentation, diagnosis and notification of the disease; management of the patient, including complications and admission to hospital; and the leprosy register and its annual review.
  Added/updated: 18 February 2010