What Is Leprosy?
Leprosy is a
chronic, progressive bacterial infection caused by the bacterium Mycobacterium
leprae. It primarily affects the nerves of the extremities, the lining of
the nose, and the upper respiratory tract. Leprosy produces skin sores, nerve
damage, and muscle weakness. If it isn’t treated, it can cause severe
disfigurement and significant disability.
Leprosy is one of the oldest diseases in recorded history.
According to the World
Health Organization (WHO), the first known written reference to leprosy is
from 600 B.C.
Leprosy is common in many countries, especially those with
tropical or subtropical climates. However, it’s not as common in the United
States. The National
Institute of Allergy and Infectious Disease reports that only 100 to 200
new cases are diagnosed in the United States each year.
What Are the Types of Leprosy?
There are three systems for classifying leprosy. The first system
recognizes two types of leprosy: tuberculoid and lepromatous. A person’s immune
response to the disease determines their type of leprosy.
The immune response is good and the disease only exhibits a few
lesions (sores on the skin) in tuberculoid leprosy.
The disease is mild and only mildly contagious.
The immune response is poor in lepromatous leprosy and affects the skin, nerves, and other
organs. There are widespread lesions and nodules (large lumps and bumps). This
disease is more contagious.
WHO categorizes the disease based on the type and number of affected
skin areas. The first category is paucibacillary,
in which five or fewer lesions with no bacteria are detected in the skin sample.
The second category is multibacillary,
in which there are more than five lesions, bacteria is detected in the skin
smear, or both.
Clinical studies use the Ridley-Jopling system. It has six classifications based on
severity of symptoms. They are:
leprosy: a few flat lesions that sometimes heal by themselves and can
progress to a more severe type
leprosy: a few flat lesions, some large and numb; some nerve
involvement; can heal on its own, persist, or may progress to a more severe
tuberculoid leprosy: lesions similar to tuberculoid but smaller and more
numerous; less nerve enlargement; may persist, revert to tuberculoid, or
advance to another form
leprosy: reddish plaques, moderate numbness, swollen lymph glands; may
regress, persist, or progress to other forms
lepromatous leprosy: many lesions including flat lesions, raised bumps,
plaques, and nodules, sometimes numb; may persist, regress, or progress
leprosy: many lesions with bacteria; hair loss; nerve involvement; limb
weakness; disfigurement; doesn’t regress
How Does Leprosy Spread?
Leprosy spreads through contact with the mucus of an infected
person. This usually occurs when the infected person sneezes or coughs. The
disease isn’t highly contagious. Close, repeated contact with an untreated
person can lead to contracting leprosy.
The bacteria responsible for leprosy multiply very slowly. The
disease has an incubation period (the
time between infection and the appearance of the first symptoms) of up to five
years. Symptoms may not appear for as long as 20 years.
According to the New England Journal
of Medicine, an armadillo native to the southern United States can also
carry and transmit the disease to humans.
What Are the Symptoms of Leprosy?
The main symptoms of leprosy include:
- muscle weakness
- numbness in the hands, arms, feet, and legs
- skin lesions
The skin lesions have decreased sensation to touch, temperature,
or pain. They don’t heal after several weeks and are lighter than your normal
How Is Leprosy Diagnosed?
Your doctor will conduct a physical exam to look for telltale
signs and symptoms of the disease. They’ll also perform a skin biopsy or scraping. Your
doctor will remove a small piece of skin and send it to a laboratory for
Your doctor may also perform a lepromin skin test to determine the form of leprosy. Your
doctor will inject a small amount of leprosy-causing bacteria into the skin,
typically on the upper forearm. People who have tuberculoid or borderline
tuberculoid leprosy will experience irritation at the injection site.
How Is Leprosy Treated?
WHO developed a multidrug therapy in 1995 to cure all types of
leprosy. It’s available free of charge worldwide. Additionally, several
antibiotics treat leprosy by killing the bacteria that causes it. These
Your doctor may prescribe more than one antibiotic at the same
time. They also may want you to take an anti-inflammatory medication such as
aspirin, prednisone, or orthalidomide. You should never take thalidomide if you
are or may become pregnant. It can produce severe birth defects.
What Are the Potential Complications of Leprosy?
Delayed diagnosis and treatment can lead to serious complications.
These can include:
- hair loss, particularly on the eyebrows and
- muscle weakness
- permanent nerve damage in the arms and legs
- inability to use the hands and feet
- chronic nasal congestion, nosebleeds, and
collapse of the nasal septum
- iritis (inflammation of the iris of the eye)
- glaucoma (an eye disease that causes damage to
the optic nerve)
- erectile dysfunction and infertility
- kidney failure
How Can I Prevent Leprosy?
The best way to prevent leprosy is to avoid long-term, close
contact with an untreated, infected person.
What Is the Long-Term Outlook?
overall outlook is good if your doctor diagnoses the leprosy promptly. Early
treatment prevents tissue damage, stops the spread of the disease, and prevents
serious health complications. The outlook is worse when diagnosis occurs at a
more advanced stage, after an individual has significant disfigurement or
disability. It may be impossible to lead a normal life despite treatment in