Leprosy is a complex infectious disease that is caused by bacteria. It is also known as Hansen's disease.
Although leprosy has been recognized as a disease for several thousands of years, Dr. Gerhard Armauer Hansen, a Norwegian scientist, first discovered the cause of leprosy in 1873. Considerable progress has been made over the last 40 years so that today the majority of cases can be treated without too much difficulty and most of the fears generated by the folklore surrounding it can be counteracted.
The disease has erroneously been associated with biblical leprosy, which scholars believe was actually a variety of skin diseases categorized under the term leprosy. Some of these conditions could have included:
The cause of leprosy is an infection with the bacteria
Mycobacterium leprae. Mycobacterium leprae are part of the family
Mycobacteriaceae. This is the same family as the bacteria that cause
tuberculosis (
Mycobacterium tuberculosis).
Mycobacterium leprae grow slowly and mainly affect the skin, nerves, and mucous membranes. It can also affect the:
- Eyes
- Muscles
- Bones
- Testes.
The illness can occur at any age, but cases of leprosy under age 1 are rare. Up to 20 percent of cases occur before the age of 10. In children, the disease occurs equally in males and females. In adults, it is twice as common in males as females.
There is a limited form of leprosy called tuberculoid or paucibacillary (few bacilli) and a more generalized form called lepromatous or multibacillary (many bacilli).
Despite first discovering
Mycobacterium leprae in 1873, research scientists still do not completely understand how the disease is spread.
Most scientists believe that it spreads from person to person through infected respiratory droplets. While this may be one mode of transmission, over half of the people who develop leprosy have no confirmed contact with an infected person. Other factors that may play a role in a person developing the condition include:
- Genetics
- The extent of exposure
- Environmental conditions.
When a person becomes infected with the bacteria that cause the disease, the bacteria begin to multiply within the body. After three to five years, symptoms can begin. This period between becoming infected and the start of symptoms is called the "leprosy incubation period." Although the incubation period for leprosy is typically between three and five years, it can range from six months to several decades.
Leprosy usually affects the skin and peripheral nerves. However, once a person starts experiencing symptoms, they can range in type and severity. The symptoms will also vary based on the form of leprosy that a person has (tuberculoid leprosy versus lepromatous leprosy).
In order to make a diagnosis, the doctor will ask a number of questions and perform a physical exam, looking at the skin and other parts of the body for signs of leprosy. If the doctor has a high suspicion that a person has the condition, he or she will likely recommend a skin biopsy.
Several other medical conditions that share common symptoms with leprosy include:
- Systemic lupus erythematosus (lupus)
- Lupus vulgaris
- Dermal leishmaniasis
- Sarcoidosis
- Peripheral neuropathy
- Yaws
- Syringomyelia.
Because leprosy can resemble other skin diseases, a diagnosis is often delayed.
Historically, there was no cure for leprosy, and lepers were segregated for extended periods of time. Today, most people with the condition are treated in the home and easily cured with antibiotics. Also, with early diagnosis and treatment, many symptoms and complications can be minimized or avoided altogether.
Treatment involves medicines along with supportive care. Supportive care is treatment of
leprosy symptoms and complications. The length of time a person is treated will vary depending upon the form of the disease that a person has. Treatment will generally continue for one year for the tuberculoid form and two years for the lepromatous form.
Leprosy is quite possibly the most common cause of crippling in the hands in the world. Other complications can include:
- Loss of fingers or toes following an injury or an infection
- Blindness
- An increased risk for arthritis and amyloidosis.
Worldwide, 1 to 2 million people are permanently disabled because of the disease.
Because leprosy can be cured with medicines
(see Cures for Leprosy), an early diagnosis will often reduce associated symptoms and complications. Therefore, while prevention is not always possible, especially where leprosy is endemic, control should be possible.
Statistics from 2002 include:
- The number of new leprosy cases detected worldwide was 763,917
- 96 cases occurring in the United States were reported to the Centers for Disease Control (CDC)
- The World Health Organization (WHO) listed Brazil, Madagascar, Mozambique, Tanzania, and Nepal as having 90 percent of leprosy cases that year.
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