Ancient origins

Hansen’s disease most likely originated in India or East Africa. Historical documents and a 4,000-year-old skeleton point to India. Genomic analysis of strains of Mycobacterium leprae indicate East Africa. Recent research suggests that M. leprae and M. lepromatosis settled in human ancestors as parasites millions of years ago.

Global spread

Trade, pilgrimage, migration, and military campaigns carried Hansen’s disease throughout the Eurasian continent and into islands in the western Pacific. Europeans introduced the disease to the Caribbean and the Americas when they crossed the Atlantic Ocean in the late 15th century. The transatlantic slave trade, which enslaved 10-12 million Africans and forced their migration to the Americas over a 400-year period, contributed significantly to spread of the disease.

“Leprosy” in the Bible

For over a thousand years, a Latin translation of the Bible known as the Vulgate was the most influential text in western Europe. The Vulgate used variants of Latin lepra to stand in for the Hebrew word zara’at and the Greek word lepra. The Old Testament instructed religious authorities to inspect skin problems and to declare the person clean or unclean according to ritual law. An unclean person would have to follow certain procedures and live “outside the camp.” In the New Testament, Jesus showed compassion to persons living as “lepers” (leprosi) and had the power to make a “leper” clean (mundare) through words and touch.

“Lepers” and “leper hospitals” in medieval Europe

The development of “leper hospitals” (leprosaria) reflected both Old and New Testament interpretations of the Bible. While these institutions were located outside of main settlements, they were usually situated along main roads and sometimes close to city gates to facilitate alms-giving and charitable donation to Christ’s favored pauperes Christi. Lepra was a divine punishment for sins, and at the same time, the suffering endured by the afflicted gave them spiritual status. Benefactors supported their religious training and sought their prayers. The Black Death of the mid-1300s destabilized society and increased persecution of the vulnerable, including persons identified as “lepers.” (Many of the ideas held today about how people with Hansen’s disease were treated in medieval Europe have been influenced by written materials and paintings from the 19th century. It is important to read histories produced since the 1990s that show diligent attention to archeological findings and primary sources from the medieval period.)

“Isolation and seclusion” as public health policy in Hawai‘i

In the mid-19th century, the Kingdom of Hawai‘i was coping with precipitous population decline as a result of diseases brought to the islands by traders, missionaries, plantation owners, and laborers. In response, King Kamehameha III organized a Board of Health in 1850. In 1863, a Prussian physician who had settled in Hawai‘i, Dr. William Hillebrand, wrote to the Board of Health, directed attention to the spread of leprosy, and recommended isolation of those affected by the disease. Two years later, King Kamehameha IV and the legislature passed an Act to Prevent the Spread of Leprosy. The Act focused on the power of the Board of Health and the police to arrest, isolate, and confine “all leprous patients who shall be deemed capable of spreading the disease.” Forced isolation began the following year, in 1866, when eight men, three women, and one boy were taken by boat to the Kalaupapa peninsula on the island of Molokai, and left there to care for themselves.

Symbiotic relationship between colonizers and missionaries

At the time that An Act to Prevent the Spread of Leprosy was signed into law, Hawai‘i was still an independent kingdom, but five of the seven members of the Board of Health were from the U.S. or Europe. This Board of Health appointed a Frenchman, Louis Lepart, as the first superintendent at Kalaupapa, but it did not provide a doctor. Care for those too ill or disabled to help themselves came first from fellow native Hawaiians, some of whom accompanied family members into exile and others who were already living on Molokai. In 1873, the Catholic Church sent a Belgian missionary known as Father Damien to the settlement. He was to tend to the souls of the Catholics among the persons with leprosy, but he provided much practical assistance to the entire community as well. He became internationally famous for his caregiving efforts and for his eventual death from leprosy at Kalaupapa in 1889. Kalaupapa was an early example of a pattern of settlers/colonizers establishing an isolation policy and then, in the absence of a medical cure, Christian missionaries providing care.

Hansen identifies Mycobacterium leprae

Leprosy had nearly disappeared from Europe by the end of the 16th century, but in the 18th century the number of patients began increasing in Norway. By the 19th century, leprosy in Norway had become a significant public health problem. A Royal Decree issued in 1856 initiated a control program through the establishment of the National Leprosy Registry of Norway and permanent municipal boards of health. In 1873, Norwegian physician Gerhard Henrik Armauer Hansen became the first person to see a bacillus through a microscope that could be linked to leprosy. His discovery of Mycobacterium leprae is celebrated today for facilitating the development of a secular, medical approach to the disease, but at the time it did not immediately lead to consensus about leprosy’s cause(s) and transmissibility. Standard ways to establish that a disease was infectious, such as transfer to experimental animals and cultivation in vitro, failed.

Hansen promotes isolation as part of leprosy control

Hansen himself did not consider discovery of the bacillus alone as proof that leprosy was a communicable disease. His confidence in contagion theory increased based on his subsequent analysis of the National Leprosy Registry. He found that the number of new cases of the disease declined most quickly in districts where isolation of patients in hospitals had been most consistently enforced. In 1875, as the newly appointed chief medical officer for leprosy, he used what he learned from the registry to argue that the nation’s control program should be altered to permit isolation of the most contagious patients. Laws passed in 1877 and 1885 required that patients either be isolated in separate rooms in their homes or admitted to a hospital. The Norwegian control program attracted international attention.

The First International Congress of Leprosy (Berlin, 1897)

In 1897, nearly 180 leprologists, dermatologists, and scientists, along with thirty delegates from various countries, gathered in Berlin for discussion of leprosy science and policy recommendations. Participants agreed to resolutions proposed by Hansen and amended by French dermatologist Ernest Henri Besnier: “all nations with local self-government and a sufficient number of physicians” were encouraged to follow Norway’s example and implement a system of compulsory registration, control, and isolation.

Support for compulsory isolation spreads worldwide

Britain had been against implementing segregation in India—mostly for practical reasons—but in 1898 enacted the Lepers Act, which authorized the arrest of “pauper lepers” and their detainment in “leper asylums.” The American government obtained colonial control of the Philippines in 1898 and four years later decided to isolate all leprosy patients on the island of Culion. In 1907, the Japanese government promulgated the first Leprosy Prevention Law and in 1909 opened five public sanatoriums. In a world without a cure, separation of the diseased from the healthy took on the meaning of a modern best practice, even as the hardship that it forced on individuals continued to be noticed and debated.

The first effective medical treatment

In 1941, Dr. Guy Henry Faget successfully treated patients at the National Leprosarium in Carville, Louisiana, United States of America, with the drug Promin. At the time, the flow of information was affected by World War II, and news of the successful treatment entered Japan via a pharmaceutical journal written in German. The article mentioned only “a sulfone compound,” but Morizo Ishidate, a professor of pharmaceutical science who later became a co-founder of Sasakawa Health Foundation, had been working on developing drugs for tuberculosis (TB) and recognized it as Promin. A laboratory under his direction successfully synthesized a small amount of the drug in 1946. With Promin, Hansen’s disease became a curable disease, but the drug could only be administered by injection and caused a number of side-effects. In 1950, researchers found that a related drug, dapsone, could be taken orally. Single drug treatment (monotherapy) with dapsone became the global standard for Hansen’s disease control programs worldwide.

Recommendation to avoid compulsory isolation

In 1953, the Expert Committee on Leprosy of the newly formed World Health Organization (WHO) issued its first report. In the section on control of the disease, the experts acknowledged that isolation was still a useful approach for infectious cases, but “compulsory isolation” had “very serious disadvantages” and should be avoided as much as possible. The “old idea” that patients should be segregated on islands and other distant places was condemned. Despite this recommendation, laws and policies were often slow to change.

From monotherapy to multidrug therapy (MDT)

Because of increasing bacterial resistance associated with dapsone monotherapy, in 1981, a WHO study group recommended the use of three drugs to treat Hansen’s disease: rifampicin, dapsone and clofazimine. Use of multidrug therapy (MDT) became the new global standard.

“Elimination” of Hansen’s disease

Encouraged by the efficacy of MDT, the 44th World Health Assembly adopted a resolution in 1991 calling for the elimination of Hansen’s disease as a public health problem by the year 2000. “Elimination” was defined as prevalence of below 1 case per 10,000 population at the global level.

MDT subsidy and donation for free treatment

In 1994, Yohei Sasakawa, as President of The Nippon Foundation (TNF), pledged US$ 50 million to the WHO to fund the free distribution of MDT around the world for five years from 1995 to 1999. In 2000, Novartis, the developer of two of the three drugs in MDT, committed to donating the medication to the World Health Organization (WHO) so that free treatment could continue. In 2021, Novartis and WHO signed a five-year extension of their partnership. Novartis agreed to continue donating multidrug therapy (MDT) medicines through the end of 2025.

Hansen’s disease as a human rights issue

With the formation of the International Association for Integration, Dignity and Economic Advancement (IDEA) in 1994, advocacy for the human rights of persons affected by Hansen’s disease spread around the world. In 2003, The Nippon Foundation approached the Office of the United Nations High Commissioner for Human Rights to propose that discrimination endured by persons affected by Hansen’s disease be recognized officially as an issue of human rights. Seven years later, in December 2010, the UN General Assembly approved the Principles and Guidelines for the Elimination of Discrimination Against Persons Affected by Leprosy and their Family Members.

Post-elimination plateau

In 2000, the WHO announced that Hansen’s disease had been eliminated as a public health problem at the global level. In 2005, India achieved the elimination target at the national level. By 2011, Mozambique, the Democratic Republic of Congo, Nepal, and East Timor also achieved elimination, leaving Brazil as the only country with a population of over 1 million yet to do so. At the sub-national level, endemic hotspots remain, and the number of registered cases worldwide has plateaued at around 200,000 annually. Governments that have achieved “elimination” no longer see the disease as a priority, and sustaining interest in Hansen’s disease has become difficult.

Involvement of persons affected by Hansen’s disease in disease-related services

In 2011, WHO published “Guidelines for strengthening the participation of persons affected by leprosy in leprosy services.” Persons affected by Hansen’s disease were actively involved in the development of these guidelines, which identified a constructive role for them in every aspect of service provision, including advocacy, counseling, training, capacity building, disability prevention and rehabilitation, program planning and operation, resource utilization, research, and evaluation.

Bangkok Declaration and a leprosy-free world

In 2013, WHO and TNF invited health ministers from seventeen high-burden Hansen’s disease countries to a jointly organized International Leprosy Summit. Participants adopted the Bangkok Declaration for Accelerating Towards a Leprosy-Free World.

Appointment of Special Rapporteur

To promote the implementation of the Principles and Guidelines for the Elimination of Discrimination Against Persons Affected by Leprosy and their Family Members, the Government of Japan proposed the appointment of a Special Rapporteur to monitor and report on progress. The proposal was co-sponsored by 43 countries, including India and Brazil, and the resolution was adopted unanimously by the United Nations Human Rights Council (UNHRC) at its 35th session. In 2017, Alice Cruz became the first UN Special Rapporteur on the Elimination of Discrimination Against Persons Affected by Leprosy and their Family Members. In 2020, the UNHRC extended her mandate for an additional three years.

Global Partnership for Zero Leprosy

In 2018, government health ministries, organizations of persons affected by Hansen’s disease, and other non-governmental organizations launched the Global Partnership for Zero Leprosy to accelerate collaborative action. “Zero leprosy” is shorthand for an ultimate goal of no disease, no disability, no discrimination, and no stigma in every country.

WHO’s Global Leprosy Strategy 2021-2030

In October 2020, WHO released a draft for a 10-year Global Leprosy Strategy aiming for zero leprosy. The Strategy focuses on interruption of transmission, and to measure progress toward this goal set targets for reductions of new cases:

Global targets for 2030

• 120 countries reporting zero new autochthonous cases
• 70% reduction in annual number of new cases detected
• 90% reduction in rate (per million) of new cases with grade-2 disability
• 90% reduction in rate (per million children) of new child cases with leprosy

Each country is expected to formulate national policy based on consideration of these global targets.