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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• Leprosy (Hansen's disease) facts
• What is leprosy?
• What is the history of leprosy (Hansen's disease)?
• What causes leprosy?
• What are the risk factors for leprosy?
• What are leprosy symptoms and signs?
• Are there different forms (classifications) of leprosy?
• How is leprosy transmitted?
• How is leprosy diagnosed?
• What is the treatment for leprosy?
• What are the complications of leprosy?
• How is leprosy prevented?
• What is the prognosis (outcomes) of leprosy?
• Where can I find more information on leprosy?
• Leprosy Index

The complications of leprosy depend on how quickly the disease is diagnosed and effectively treated. Very few complications occur if the disease is treated early enough, but the following is a list of complications that can occur when diagnosis and treatment is either delayed or started late in the disease process:

• Sensory loss (usually begins in extremities)
• Permanent nerve damage (usually in extremities)
• Muscle weakness
• Progressive disfigurement (for example, eyebrows lost, disfigurement of the toes, fingers, and nose)

In addition, the sensory loss causes people to injure body parts without the individual being aware that there is an injury; this can lead to additional problems such as infections and poor wound healing.

Prevention of contact with droplets from nasal and other secretions from patients with untreated M. leprae infection currently is a way recommended to avoid the disease. Treatment of patients with appropriate antibiotics stops the person from spreading the disease. People who live with individuals who have untreated leprosy are about eight times as likely to develop the disease, because investigators speculate that family members have close proximity to infectious droplets. Leprosy is not hereditary, but recent findings suggest susceptibility to the disease may have a genetic basis.

Many people get exposed to leprosy throughout the world, but the disease in not highly contagious; researchers suggest that over 95% of exposures result in no disease, and further studies suggest that susceptibility may be based,  in part, by a person's genetic makeup. In the U.S., there are about 200-300 new cases diagnosed per year, with most coming from exposures during foreign travel. The majority of worldwide cases are found in the tropics or subtropics (for example, Brazil, India, and Indonesia). The WHO reports about 500,000 to 700,000 new cases per year worldwide, with curing of about 14 million cases since 1985.

There is no commercially available vaccine available to prevent leprosy. However, there are reports of using BCG vaccine, the BCG vaccine along with heat-killed M. leprae organisms, and other preparations that may be protective or help to clear the infection or to shorten treatment. Except for BCG in some countries, these preparations are not readily available.

Animals (chimpanzees, mangabey monkeys, and nine-banded armadillos) rarely transfer M. leprae to humans; nonetheless, handling such animals in the wild is not advised. These animals are a source for endemic infections.