Hansen's diseaseHansen's disease, also known as leprosy, is an infectious disease caused by infection by Mycobacterium leprae, named after its discoverer G. A. Hansen. Sufferers from Hansen's disease have generally been called lepers, although term is falling into disuse both from the diminishing number of leprosy patients and from pressure to avoid the demeaning connotations of the term. Leprosy used to be incurable, and severely disfiguring. Lepers were shunned and sequestered in "leper colonies". Now known as Hansen's disease, leprosy is easily curable by multidrug antibiotic therapy. The main challenges for Hansen's disease elimination efforts are to reach populations that have not yet received multidrug therapy services, improve detection of the disease, and provide patients with high-quality services and free drugs. Clinical Features This chronic infectious disease usually affects the skin and peripheral nerves but has a wide range of possible clinical manifestations. Patients are classified as having paucibacillary or multibacillary Hansen's disease. Paucibacillary Hansen's disease is milder and characterized by one or more hypopigmented skin macules. Multibacillary Hansen's disease is associated with symmetric skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa resulting in nasal congestion and epistaxis. Etiologic Agent The cause of this disease is a bacillus, Mycobacterium leprae, that multiplies very slowly and mainly affects the skin, nerves, and mucous membranes. The organism has never been grown in bacteriologic media or cell culture, but has been grown in mouse foot pads. It is related to M. tuberculosis, the bacillus that causes tuberculosis. Incidence In 1999, the world incidence of Hansen's disease was estimated to be 640,000; and in 2000, 738,284 cases were identified. In 1999, 108 cases occurred in the United States. In 2000, the World Health Organization (WHO) listed 91 countries in which Hansen's disease is endemic, with India, Myanmar, and Nepal having 70% of cases. Sequelae Worldwide, 1-2 million persons are permanently disabled as a result of Hansen's disease. However, persons receiving antibiotic treatment or having completed treatment are considered free of active infection. Transmission Although the mode of transmission of Hansen's disease remains uncertain, most investigators think that M. leprae is usually spread from person to person in respiratory droplets. What is known is that the transmission rate is very low. Risk Groups Close contacts with patients with untreated, active, predominantly multibacillary disease, and persons living in countries with highly endemic disease. Surveillance Hansen's disease is nationally notifiable in the United States. Trends Incidence/prevalence has remained relatively stable in the United States. There are decreasing numbers of cases worldwide, with pockets of high prevalence in certain countries. Opportunities Hansen's disease in the Western Pacific is a particular problem and opportunities exist for participation in Hansen's disease elimination activities in endemic-disease countries, and in the Republic of the Marshall Islands. Asylums There are a few 'leper colonies' around the world. In the United States on the tiny island of Molokai in the Hawaiian chain is the oldest leper colony in America. Government run leper colonies in Japan in 2001 came under judicial scrutiny ruling the Japanese government had mistreated the patients. Leper colonies are located in India and the Philippines, with high likelihood there are many more in many more countries.