Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by the bacterium Mycobacterium leprae. This disease primarily affects the skin and peripheral nerves, and if left untreated, can lead to progressive and permanent disabilities. While the term “leper” historically carried significant stigma, understanding the facts about leprosy is crucial to eliminating misconceptions and promoting effective treatment.
Leprosy: An Overview
Leprosy mainly affects the skin, peripheral nerves, mucosa of the upper respiratory tract, and the eyes. Beyond the physical effects, individuals affected by leprosy often face stigma and discrimination. Early diagnosis and treatment are key to preventing disabilities and improving the quality of life for those affected. The disease is curable with multidrug therapy (MDT).
The Scope of Leprosy Today
Leprosy is classified as a neglected tropical disease (NTD) that still exists in over 120 countries. Although global elimination as a public health problem (defined as a prevalence of less than 1 per 10,000 population) was achieved in 2000, new cases continue to be reported.
According to 2023 data, Brazil, India, and Indonesia report the highest numbers of new cases annually. Another 12 countries, including Bangladesh, Democratic Republic of the Congo, Ethiopia, Madagascar, Mozambique, Myanmar, Nepal, Nigeria, Philippines, Somalia, Sri Lanka, and the United Republic of Tanzania, each reported between 1,000 and 10,000 new cases.
How Leprosy is Transmitted
The transmission of Mycobacterium leprae occurs via droplets from the nose and mouth of individuals with untreated leprosy, usually after prolonged, close contact. It’s important to note that leprosy doesn’t spread through casual contact, such as shaking hands, hugging, sharing meals, or sitting next to someone. Once treatment begins, the patient is no longer infectious.
Diagnosing Leprosy
Leprosy diagnosis is primarily clinical, although laboratory services may be required in complex cases. The disease typically manifests through skin lesions and peripheral nerve involvement.
Key signs for diagnosis include:
- Definite loss of sensation in a pale (hypopigmented) or reddish skin patch.
- Thickened or enlarged peripheral nerve, with loss of sensation and/or muscle weakness supplied by that nerve.
- Microscopic detection of bacilli in a slit-skin smear.
Based on these criteria, leprosy cases are classified for treatment as either paucibacillary (PB) or multibacillary (MB).
- PB case: 1-5 skin lesions, without evidence of bacilli in a skin smear.
- MB case: More than five skin lesions; or nerve involvement; or presence of bacilli in a slit-skin smear, regardless of the number of skin lesions.
Effective Treatment Options
Leprosy is a curable disease. Multidrug therapy (MDT), consisting of dapsone, rifampicin, and clofazimine, is the recommended treatment. WHO recommends a 6-month duration for PB cases and 12 months for MB cases. MDT effectively kills the bacteria and cures the patient, and early diagnosis and treatment can prevent disabilities. The World Health Organization (WHO) provides MDT free of charge, initially funded by The Nippon Foundation (TNF) and donated by Novartis since 2000.
Prevention Strategies
Case detection and MDT treatment alone are not sufficient to stop leprosy transmission. WHO recommends contact tracing (household, neighborhood, and social contacts) combined with a single dose of rifampicin as post-exposure prophylaxis (SDR-PEP).
The WHO’s Response to Leprosy
The World Health Organization (WHO) supports countries in their leprosy prevention and control efforts. Each year, the WHO collects epidemiological data from countries and publishes a consolidated report. The WHO released the “Towards zero leprosy: global leprosy (Hansen’s disease) strategy 2021–2030,” aligned with the Neglected Tropical Diseases road map 2021–2030, which envisions zero leprosy: zero infection and disease, zero disability, and zero stigma and discrimination.
The strategy’s pillars include:
- Implementing integrated, country-owned zero leprosy roadmaps.
- Scaling up prevention alongside active case detection.
- Managing leprosy and its complications to prevent new disabilities.
- Combating stigma and ensuring human rights.
The WHO also emphasizes the need for research and has developed e-learning modules to improve healthcare workers’ knowledge and skills in leprosy diagnosis, treatment, and disability management.
Conclusion
Leprosy is a curable disease, and understanding its causes, transmission, and treatment is crucial for eliminating stigma and promoting effective prevention and care. With continued global efforts and adherence to WHO’s strategies, the vision of zero leprosy is achievable.
