What is Hansen’s disease (leprosy)?

Hansen’s disease (leprosy) is a chronic bacterial disease caused by Mycobacterium leprae. Leprosy is characterized by the involvement primarily of skin as well as peripheral nerves and the mucosa (lining) of the upper airway.

There are four major forms of the disease:

• Tuberculoid: one or a few well-demarcated, hypopigmented, and anesthetic (without feeling) skin lesions, frequently with active, spreading edges and a clearing center; peripheral nerve swelling or thickening also may occur
• Lepromatous: a number of reddened bumps that may occur on the face, hands and feet with skin lesions in a bilateral and symmetrical distribution that progress to thickening of the skin
• Borderline (dimorphous): skin lesions characteristic of both the tuberculoid and lepromatous forms
• Indeterminate: early lesions, usually hypopigmented bumps, without developed tuberculoid or lepromatous features

Who gets Hansen’s disease?

Anyone can get Hansen’s disease if they become infected with M. leprae. Most people who become infected have had prolonged contact with someone else who already has leprosy.

Leprosy is very rare in the United States, but is common in other parts of the world. Places where leprosy is common include South and Southeast Asia and some parts of Latin America.

How is Hansen’s disease spread?

The exact mode of transmission for leprosy has never been determined but prolonged contact with an infected person appears to be necessary for transmission.

What are the symptoms of Hansen’s disease?

People with Hansen’s disease develop the characteristic skin lesions and have decreased sensation in the area where the skin lesions have developed.

How soon after exposure do symptoms appear?

This is variable and can range from nine months to 20 years.

How is Hansen’s disease diagnosed?

The laboratory criteria for diagnosis include:

• Demonstration of acid-fast bacilli in skin or dermal nerve, obtained from the full thickness biopsy of a lepromatous lesion.
• A case of Hansen’s disease (leprosy) is confirmed when a clinically compatible case is also laboratory confirmed.

What is the treatment for Hansen’s disease?

Doctors can prescribe antibiotics for leprosy.

How can Hansen’s disease be prevented?

Hansen’s disease is extremely rare in the United States. It is also very slow to develop and can be treated successfully with antibiotics.

In parts of the world where leprosy is common, the best way to prevent more people from getting leprosy is to promptly recognize and treat those individuals who are already afflicted.

Where can I get more information?

Contact your doctor, the Southern Nevada Health District, Office of Epidemiology at (702) 759-1300 or the Centers for Disease Control and Prevention.
Case definitions for infectious conditions under public health surveillance. MMWR 1997; 46 (No. RR-10):15-16.