Leprosy (Hansen’s disease), one of the 21 Neglected Tropical Diseases (NTDs), is caused by the bacillus Mycobacterium leprae (M. leprae). M.leprae multiplies very slowly, often inside the Schwann cells of the peripheral nervous system. The incubation period of the disease is on average four to five years, but in some cases symptoms can take as long as 20 years to appear. More than 174,000 new cases per year are reported globally, with a majority of the cases found in low-income communities. Approximately two-thirds of newly found leprosy patients are reported in India, followed by Brazil and Indonesia. The disease mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract and the eyes. It can cause disabilities if not accurately treated in time. Besides physical consequences, persons affected by leprosy often also face stigmatization, discrimination and negative socio-economic consequences of this disease.
The transmission of leprosy occurs through droplets released from the nose and mouth. Prolonged and close contact over an extended period, typically months, with an individual who has untreated leprosy is needed for transmission. Casual interactions, such as shaking hands, hugging, sharing meals, do not facilitate the spread of the disease.
The diagnosis of leprosy is primarily clinical, with laboratory-based services considered in challenging cases or when available. The disease typically presents through skin lesions and peripheral nerve involvement. Diagnosis involves identifying at least one of the following signs: (1) loss of sensation in a pale or reddish skin patch; (2) thickened or enlarged peripheral nerve with sensory loss and/or linked muscle weakness; (3) microscopic detection of bacilli in a slit-skin smear.
Based on these criteria, cases are categorized into two types (WHO classification):
- Paucibacillary (PB) leprosy: a patient with 1 to 5 skin lesions, without demonstrated bacilli presence in a skin smear.
- Multibacillary (MB) leprosy: a patient with >5 skin lesions, and/or nerve involvement or demonstrated bacilli presence in a slit-skin smear, regardless of the number of skin lesions.
Leprosy is curable and early treatment with a combination of the antibiotics dapsone, rifampicin and clofazimine. This drug combination is called multidrug therapy (MDT) and usually prevents disability if started in time. The treatment period is 6 to 12 months, depending on the leprosy type. A few days after taking MDT, a leprosy patient is no longer infectious. WHO is providing MDT free of charge to countries which are reporting new leprosy patients.
Additional treatment or support - such as steroids, pain relief, physical therapy, reconstructive surgery or psychological support - may needed when persons affected by leprosy experience complications or secondary effects of the disease.
Leprosy related disabilities
When left untreated leprosy can cause permanent damage to the skin, nerves, limbs and eyes. Once peripheral nerves are affected, loss of sensation can occur in eyes, hands or feet. As a result, injuries may go unnoticed (i.e. burns or cuts), become infected and can lead to disabilities. New nerve damage can also occur in the years after completing leprosy treatment, because of immunological reactions to the bacterial antigen which still remains in the body for some time. The total number of individuals who live with leprosy-related disabilities is estimated to be between one and two million.
Administering MDT to leprosy patients alone is inadequate to halt transmission. WHO therefore advises to screen household contacts, neighbours and social contacts of patients (after his/her/their consent). Contact screening should be combined with the administration of a single dose of rifampicin (SDR) as a form of post-exposure prophylaxis (PEP). Research shows that this offers a protective effect of around 60%.
Stigma and discrimination
Persons affected by leprosy frequently experience stigma, social-exclusion and discrimination. This can affects the mental wellbeing, potentially resulting in depression and anxiety. Globally, there exist over 100 laws that impose discriminatory measures against individuals who have encountered leprosy which still need to be abolished.
Leprosy related stigma is often linked to misconceptions about the disease. Besides promoting early diagnosis and the start of appropriate treatment, education on leprosy for both health workers and communities are vital to decrease stigma. In addition, attention to mental wellbeing and the socio-economic effects of leprosy should be embedded in leprosy control. The ILEP Guides on Stigma and Mental Wellbeing are a useful tool to incorporate these topics into leprosy programmes.