Leprosy

Primary reference(s)

WHO, 2019. Leprosy. World Health Organization (WHO). Accessed 4 November 2020.

Additional scientific description

Leprosy is an age-old disease, described in the literature of ancient civilizations. Leprosy has struck fear into human beings for thousands of years and was well recognised in the oldest civilizations of China, Egypt and India. A cumulative total of the number of individuals who, over the millennia, have suffered its chronic course of incurable disfigurement and physical disabilities can never be calculated (WHO, no date a).

Since ancient times, leprosy has been regarded by the community as a contagious, mutilating and incurable disease. There are many countries in Asia, Africa and Latin America with a significant number of leprosy cases. It is estimated that there are between one and two million people visibly and irreversibly disabled due to past and present leprosy who need to be cared for by the community in which they live (WHO, no date a). Throughout history, people afflicted have often been ostracised by their communities and families (WHO, 2019).

Mycobacterium leprae multiplies slowly, meaning that symptom onset can range from one to twenty years from infection, with an average incubation period of five years. Clinical presentation is characterised by progressive and permanent damage to the skin, nerves, limbs and eyes if untreated, leading to deformities and disabilities. The exact mechanism of transmission of leprosy is not known (WHO, no date b).

Laboratory diagnosis is via the identification of acid-fast bacilli in a slit-skin smear. Other tests (such as serological markers) are associated with low diagnostic accuracy (WHO, 2018).

The first breakthrough for leprosy treatment occurred in the 1940s with the development of the medicine dapsone. The duration of treatment lasted many years, often a lifetime, making compliance difficult. In the 1960s, M. leprae started to develop resistance to dapsone, the only known anti-leprosy medicine at that time. In the early 1960s, rifampicin and clofazimine were discovered and found to be effective (WHO, 2019).

In 1981, the World Health Organization (WHO) recommended multidrug therapy. The currently recommended multidrug therapy regimen consists of medicines: dapsone, rifampicin and clofazimine. This treatment lasts for six months for pauci-bacillary and 12 months for multi-bacillary cases. Multidrug therapy kills the pathogen and cures the patient. Since 1995, the WHO has provided multidrug therapy for leprosy free of cost. Free multidrug therapy was initially funded by The Nippon Foundation, and since 2000 it is donated through an agreement with Novartis until at least 2020. More than 16 million leprosy patients have been treated with multidrug therapy over the past 20 years (WHO, 2019).

The Centers for Disease Control and Prevention has published information on Hansen’s Disease/Leprosy case definitions (CDC, 2013).

Metrics and numeric limits

The elimination of leprosy as a public health problem is defined as a registered prevalence of less than 1 case per 10,000 population. This was achieved globally in 2000, but pockets of higher prevalence within some countries continue to persist. Based on 184,212 cases at the end of 2018, the prevalence rate corresponds to 0.2/10,000 (WHO, 2019).

Examples of drivers, outcomes and risk management

In 2016, the WHO launched the Global Leprosy Strategy 2016–2020, which aims to reinvigorate efforts to control leprosy and avert disabilities, especially among children still affected by the disease in endemic countries. The strategy emphasises the need to sustain expertise and increase the number of skilled leprosy staff, improve the participation of affected persons in leprosy services and reduce visible deformities as well as stigmatisation associated with the disease. It also calls for renewed political commitment and enhanced coordination among partners while highlighting the importance of research and improved data collection and analysis (WHO, 2016b).

The key interventions needed to achieve the targets include: detecting cases early before visible disabilities occur, with a special focus on children as a way to reduce disabilities and reduce transmission; targeting detection among higher risk groups through campaigns in highly endemic areas or communities; and improving health care coverage and access for marginalised populations (WHO, 2016b).

Endemic countries need to include other strategic interventions in their national plans to meet the new targets, namely: screening all close contacts of persons affected by leprosy; promoting a shorter and uniform treatment regimen; and incorporating specific interventions against stigmatisation and discrimination (WHO, 2016b).