Leprosy: Causes, symptoms, diagnosis, treatment
Leprosy is an infectious skin and nerve disease which can also affect the eyes and respiratory system.
There are no recent recorded cases of anyone catching or spreading leprosy in the UK, though there is a risk of infection in some places abroad, including Africa, Asia and Latin America.
Leprosy can only be caught through close and repeated contact with nose and mouth droplets from someone with untreated, severe leprosy. Children are more likely to get leprosy than adults.
What causes leprosy?
Leprosy is caused by a slow-growing type of bacteria called Mycobacterium leprae (M. leprae). Leprosy is also known as Hansen's disease, after the scientist who discovered M. leprae in 1873.
What are the symptoms of leprosy?
Leprosy primarily affects the skin and the nerves outside the brain and spinal cord, called the peripheral nerves. It may also strike the eyes and the thin tissue lining the inside of the nose.
The main symptom of leprosy is disfiguring skin sores, lumps, or bumps that do not go away after several weeks or months. The skin sores are pale-coloured.
Nerve damage can lead to:
- Loss of feeling in the arms and legs
- Muscle weakness
It takes a very long time for symptoms to appear after coming into contact with the leprosy-causing bacteria. Some people do not develop symptoms until 20 or more years later. The time between contact with the bacteria and the appearance of symptoms is called the incubation period. Leprosy's long incubation period makes it very difficult for doctors to determine when and where a person with leprosy originally became ill.
Forms of leprosy
Leprosy is characterised according to the number and type of skin sores you have. Specific symptoms and your treatment depend on the type of leprosy you have. The types are:
Paucibacillary/tuberculoid. A mild, less severe form of leprosy. People with this type have only one or a few patches of flat, pale-coloured skin (paucibacillary leprosy). The affected area of skin may feel numb because of nerve damage underneath. Tuberculoid leprosy is less contagious than other forms.
Multibacillary/lepromatous. A more severe form of the disease. It involves widespread skin bumps and rashes (multibacillary leprosy), numbness and muscle weakness. The nose, kidneys and male reproductive organs may also be affected. It is more contagious than tuberculoid leprosy.
Borderline. People with this type of leprosy have symptoms of both the tuberculoid and lepromatous forms.
How is leprosy diagnosed?
If you have a suspicious skin sore, your doctor will remove a small sample of the abnormal skin and send it to a laboratory to be examined. This is called a skin biopsy. A skin smear test may also be done. With paucibacillary leprosy, no bacteria will be detected. In contrast, bacteria are expected to be found on a skin smear test from a person with multibacillary leprosy.