How Is Leprosy Spread and What Is the Treatment for It?

Leprosy dates back to ancient times and is one of the oldest recorded diseases. It is endemic in the tropical and subtropical areas of the world, with Brazil, Indonesia, and India having the highest case rates. There are approximately 250,000 cases worldwide every year, with about 250 in the U.S. One-fifth of those cases are in Florida, and the numbers are rising. Read on to learn what causes leprosy, what are the signs and symptoms, and how to diagnose and treat it.

Key takeaways:

What is leprosy?


Leprosy, also known as Hansen's disease, is a bacterial infection caused by the microorganism Mycobacterium leprae. It is called Hansen's disease after the Norwegian physician who discovered the bacteria, Dr. Gerhard Hansen. Leprosy preferentially attacks the skin, nerves, eyes, and mucosa of the upper respiratory tract.

Leprosy is endemic to certain parts of the world. This means it is highly prevalent in certain tropical and subtropical areas of the world, but it is not spreading out of control. It is a slow-growing bacteria that is difficult to contract without prolonged close contact over months. Leprosy cases in India, Brazil, and Indonesia account for over 80% of all cases worldwide. Africa, Southeast Asia, and the Philippines account for about 14% of all cases. Interestingly, Florida accounts for 20% of all U.S. cases, and the number is increasing. In fact, leprosy is considered endemic in Florida, probably due to the recent influx of people from other endemic countries.

How do you get leprosy?

Leprosy is not a highly contagious infection. It can take up to 5 years after the initial infection to begin to show signs. In some patients, it has taken 20 years. Only about 5% of people exposed to leprosy will develop symptoms because 95% of people have natural immunity.

You can contract leprosy in several ways:

  • Inhaling respiratory droplets from an infected person, such as from a cough or sneeze
  • Close, repeated skin contact with an untreated, infected patient
  • Contact with armadillos, which carry the disease

Types of leprosy

There are three different classifications of leprosy. The first one relates to the patient's immune response to the bacteria. Another classification system involves the type and number of lesions present in the patient. Finally, the last one stems from the severity of symptoms experienced by the patient.


Immune response classification, Immune response:

  • Tuberculoid leprosy. Immune response is good, so there are a few lesions, and the disease is mild.
  • Lepromatous leprosy. Immune response is poor, so there are many lesions, and the disease is severe.
  • Borderline leprosy. Features of both.

World Health Organization classification, type and number of lesions:

  • Paucibacillary. Five or fewer lesions and no bacteria detected.
  • Multibacillary. More than five lesions and numerous bacteria detected.

Ridley-Jopling classification, severity of symptoms:

  • Tuberculoid leprosy (TL). One or few flat lesions, some large lesions with numbness, and some nerve involvement.
  • Borderline tuberculoid leprosy (BT). Similar to TL but lesions are more numerous and there is more nerve involvement.
  • Mid-borderline leprosy (BB). Thicker red lesions (plaques), moderate numbness, more nerve involvement, and swollen lymph nodes.
  • Borderline lepromatous leprosy (BL). Many thick lesions and bumps (nodules) and more numbness.
  • Lepromatous leprosy (LL). Many lesions, hair loss, severe nerve involvement, weakness, and disfigurement.

Diagnosis of leprosy

Prompt diagnosis is critical to complete recovery and prevention of irreversible complications. Physicians often diagnose leprosy with a thorough physical examination of the skin, upper respiratory tract, eyes, and nervous system. If the diagnosis is unclear, a skin or nerve biopsy may be required. Also, the lepromin skin test is an alternative diagnostic test, but it can only detect tuberculoid or borderline tuberculoid leprosy.

Signs and symptoms of leprosy

Patients with leprosy can exhibit various signs and symptoms. The bacteria preferentially infects the skin, nervous system, eyes, and upper respiratory tract. However, 90% of patients with leprosy will exhibit numbness.


Here are the most common signs and symptoms of leprosy:

  • Skin. Flat lesions with lighter or darker color change or redness, bumps on the face or earlobes, painless ulcers, hair loss on the brows and lashes, thickened skin, dry skin, or burning sensation.
  • Nerves. Numbness or enlarged and tender nerves.
  • Muscles. Weakness, atrophy, or paralysis.
  • Disfigurement. Crippled with the loss of fingers or toes.
  • Upper respiratory tract. Saddle nose deformity, nosebleeds, or nasal congestion.
  • Eyes. Blindness, glaucoma, corneal ulcers, or dry eyes.
  • Reproductive. Infertility or erectile dysfunction.
  • Kidney. Renal failure.

Treatments for leprosy

Leprosy is a treatable disease, which, when diagnosed early, will not lead to any permanent complications or disfigurements. The treatment involves the use of multiple antibiotics to prevent the development of bacterial resistance. Paucibacillary leprosy patients receive treatment with a combination of dapsone and rifampin. Multibacillary leprosy patients undergo the same treatment regimen plus clofazimine. For certain patients, minocycline or ofloxacin are possible substitutions. Steroids help alleviate nerve pain. Thalidomide is also beneficial for the treatment of leprosy nodules (bumps).

It can take 1–2 years of antibiotic treatment before complete resolution of the infection occurs. If patients stop their treatment prematurely, the infection will continue, and permanent disfigurement will occur. The good news is that, as soon as you begin treatment, you are no longer contagious to others.

How to prevent leprosy

Leprosy is preventable if you adhere to these practices. You must avoid close, continued contact with infected patients. If you experience contact with infected persons, practice good hygiene by washing your hands thoroughly. Also, avoid contact with armadillos and mangabey monkeys, which carry the bacteria. Finally, avoid travel to endemic areas if possible.

Leprosy, while a devastating and debilitating disease, is treatable and preventable. The key to avoiding permanent disfigurement and disability is prompt diagnosis and complete treatment. If you develop any new lesions, rashes, or numbness, see your doctor immediately.

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