What Causes Leprosy?
Leprosy is a bacterial infection caused by Mycobacterium leprae. This disease has a long incubation period, taking between five and 20 years from infection until the appearance of symptoms, which can make it difficult to know where or when someone contracted the illness. Children are more likely than adults to get the disease.
Leprosy is classified into six forms based on the severity of symptoms on a scale called the Ridley-Jopling system, which is outlined on MedicineNet:
● Intermediate leprosy: This form is characterized by flat lesions that may heal on their own. In some cases, this type of leprosy can progress to a more serious type.
● Tuberculoid leprosy: Characterized by flat lesions, some of which are large and numb and some involve the nerve. The condition may go away by itself, persist as it is or may become more severe.
● Borderline tuberculoid leprosy: Characterized by lesions similar to tuberculoid leprosy but are smaller and more numerous. The condition may persist as it is, regress to tuberculoid leprosy, or become another type of leprosy.
● Mid-borderline leprosy: Characterized by reddish plaques, some degree of numbness and swollen lymph glands. Again, the condition may regress, stay the same or become another type of leprosy.
● Borderline lepromatous leprosy: Characterized by numerous lesions, featuring flat lesions, raised bumps, plaques, and nodules. The condition may stay the same, regress, or become another type of leprosy.
● Lepromatous leprosy: This type of leprosy features numerous lesions with bacteria, hair loss, nerve involvement, limb weakness, and disfigurement. It does not regress.
How Is It Spread?
Leprosy is spread from person to person through a cough or contact with fluid from the nose of someone who is infected with the disease. This condition occurs more commonly among those living in poverty.
While those suffering from leprosy were often isolated in leper colonies (and, in fact, leper colonies still exist in some countries of the world, including India, China and Africa), this disease is not as contagious as other communicable diseases.
Globally, as of 2012, there are about 189,000 chronic cases of leprosy and 230,000 new cases. This number has decreased from more than 5.2 million cases in the 1980s, with a total of about 16 million people worldwide having been cured of the disease in the past 20 years. About 200 cases are reported each year in the United States, mostly in the South, California, Hawaii and U.S. islands.
What Are the Signs of Leprosy?
Many of the early signs of leprosy are subtle and occur over long periods of time (usually years), making it a difficult disease to diagnose in its early stages. Later signs and symptoms are more characteristic and identifiable. Among the symptoms that occur during the progression of the disease:
Numbness and Loss of Temperature Sensation
A gradual feeling of numbness and a loss of temperature sensation are some of the earliest symptoms that patients with leprosy experience. Because these symptoms develop slowly, usually over a period of years, they may go unnoticed for longer than a condition with a sudden onset.
Loss of Touch Sensation
As the disease progresses, the bacteria continue to attack and permanently damage the nerves, which causes patients to experience a decreased or lost sense of touch, then pain and eventually deep pressure. This is particularly dangerous because injuries to extremities may go unnoticed or untreated.
Painless Ulcers and Skin Lesions
Flat, pale areas of skin develop on leprosy patients, called lesions. These skin lesions have a lighter pigmentation than normal skin color, as well as decreased sensitivity to touch, heat or pain. They may not heal after several weeks or months and may accompany growths on the skin and thick, stiff, or dry skin. Ulcers may develop on the body, including on the soles of the feet.
Eye Damage
Leprosy can damage facial nerves, causing the eyelid muscles to stop working properly. Because the eyes no longer are protected by the blinking mechanism, and because they can be so easily damaged, this can eventually lead to blindness.
Muscle Weakness
Muscle weakness or paralysis may occur as the disease progresses, especially in the hands and feet and may spread to the arms and legs. This muscle paralysis can cause clawed fingers and foot drop, both characteristic of leprosy patients.
Loss of Digits and Facial Disfigurement
Contrary to popular belief, leprosy itself does not cause its victims to lose body parts. However, because a loss of sensation occurs, injuries from burns, fractures and other injuries, may go unnoticed, and may lead to complications. According to the American Leprosy Missions:
“Without feeling pain, people injure themselves, and the injuries can become infected, resulting in tissue loss. Fingers and toes become shortened and deformed as the cartilage is absorbed back into the body, and repeated injury and infection of number areas in the fingers and toes can cause the bones to shorten. The tissues around them shrink, making them short.”
This long-term progression of the illness begins and focuses on the cooler areas of the body -- namely, the hands, feet, face and knees.
What Should I Do If I Think I Have Leprosy?
If you have symptoms of leprosy, it’s important that you contact your healthcare provider immediately to begin treatment because while this disease can be cured, the damage that it causes cannot be reversed.
Your healthcare provider will administer lab tests to confirm the diagnosis. The disease is curable with the medications dapsone and rifampicin for a period of six months for less severe cases, and by doses of rifampicin, dapsone and clofazimine for 12 months in more severe cases -- or other antibiotic combinations may be prescribed.
In the United States, cases of leprosy need to be reported to the Centers for Disease Control and Prevention (CDC).