Leprosy 

• Leprosy is endemic in 24 countries.
• 1.6 billion people worldwide are exposed to leprosy.
• 300,000 new cases are found each year, that's over 1,300 cases every day.
• It is estimated that four to five million people already suffer from or have deformities due to leprosy.

IDRI's Efforts

In a partnership with the American Leprosy Missions, IDRI has embarked on an aggressive program to develop an effective vaccine and better diagnostic tests for leprosy. Our approach to leprosy is similar to what has proven successful with tuberculosis and leishmaniasis: identify and produce specific proteins from the organism and combine these with an effective adjuvant. We anticipate that our efforts will be aided by progress made with other vaccines and by the availability of the M. leprae genome sequence.

About Leprosy

Leprosy, or Hansen's disease, is a chronic infectious disease caused by the pathogen Mycobacterium leprae --a bacterium that is related to the organism that causes tuberculosis (TB). The bacillus primarily grows within lesions on cooler areas of the body, such as the skin, limbs, eyes, and nasal cavity. In addition, damage to the peripheral nerves leads to muscle weakness and atrophy, and numbness or loss of sensitivity to touch. Leprosy bacilli are transmitted through droplets from the nose and mouth of infected people. The stigma attached to leprosy has often caused those who contract the disease to be shunned by family, friends, and society.

Historically, leprosy has afflicted people in nearly every part of the world. Today, it is still considered a public health problem in 24 countries in Africa, Asia, and Latin America, most likely due to socio-economic factors. Although the World Health Organization (WHO) has declared leprosy to be under control in many previously endemic countries, most experts agree that current measures alone are not sufficient to eliminate this disease as a public health problem. Indeed, statistics show a 7% (50,000 cases) increase in the number of new cases detected in the last year. It is projected that an additional 2.5 million cases of leprosy will be identified in the next five years.

What More is Needed to Stop Leprosy?

Approximately 25 years ago, it became possible to treat leprosy with a multidrug therapy (MDT). Although drug therapy during the early stages of the disease reduces its progression and spread, poor diagnostics and lack of access to regular health care often mean that many who develop leprosy are treated late in the disease, after disfigurement and transmission to others have already occurred. Despite the therapeutic success achieved with MDT in leprosy patients, more work is needed. Considering that the incubation period for the disease can be up to 20 years, a vaccine and diagnostic tests to prevent the disease will ultimately lead to its elimination.

Thus far there has been variable success in human vaccination using BCG or BCG plus heat-killed Mycobacteria, with reported protection rates ranging from almost zero to 60%. Therefore, the main control strategy of case finding and treatment with MDT or BCG, while promising, is less than ideal to decrease the incidence and severity of human leprosy. Development of safe, precise and low-cost diagnostic tests to detect infection with the leprosy bacterium before signs and symptoms appear would bolster any leprosy elimination program.