Table of contents
Leprosy
Background
Overview
Definition
Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by Mycobacterium leprae. It primarily affects the skin, peripheral nerves, mucosa of the upper respiratory tract, and eyes.
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Pathophysiology
Mycobacterium leprae, a non-spore-forming AFB, primarily invades via the respiratory route through the nasal mucosa, though other transmission routes may also occur. It thrives in cooler regions of the body, particularly the skin, with a preference for macrophages, keratinocytes, and Schwann cells. Armadillos may serve as a zoonotic reservoir.
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Epidemiology
Leprosy was globally eliminated as a public health problem in 2000, defined by a prevalence of < 1 case per 10,000 population. In 2023, there were 182,815 new cases of leprosy worldwide, with only 225 cases reported in the US.
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Risk factors
Risk factors include living in endemic countries and close contact with patients with leprosy, particularly those with multibacillary disease.
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Disease course
Leprosy presents with a wide spectrum of clinical findings, most commonly as erythematous or plaque-like skin lesions. It is classified into two main types: paucibacillary, defined as 1-5 lesions without detectable bacilli in a skin smear, which includes tuberculoid and borderline tuberculoid forms; and multibacillary, defined as > 5 skin lesions with nerve involvement or detectable bacilli in a slit-skin smear, regardless of the number of skin lesions. Peripheral nerve damage in leprosy results in sensory and motor function loss.
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Prognosis and risk of recurrence
Leprosy is a curable disease with supervised multidrug therapy for fixed durations being highly effective for all forms of the disease.
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Guidelines
Key sources
The following summarized guidelines for the evaluation and management of leprosy are prepared by our editorial team based on guidelines from the World Health Organization (WHO 2018).
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Screening and diagnosis
Medical management
Antimycobacterial therapy: as per WHO 2018 guidelines, consider administering the same 3-drug regimen of rifampicin, dapsone, and clofazimine in all patients with leprosy, for a duration of 6 months for paucibacillary leprosy and 12 months for multibacillary leprosy:
Situation
Guidance
Adults
Rifampicin 600 mg once a month
Dapsone 100 mg daily
Clofazimine 300 mg once a month and 50 mg daily
Children aged 10-14 years
Rifampicin 450 mg once a month
Dapsone 50 mg daily
Clofazimine 150 mg once a month and 50 mg on alternate days
Children aged < 10 years or < 40 kg
Rifampicin 10 mg/kg once month
Dapsone 2 mg/kg daily
Clofazimine 100 mg once a month and 50 mg twice weekly
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Preventative measures
Chemoprophylaxis: as per WHO 2018 guidelines, consider administering single-dose rifampicin as a preventive treatment in contacts with patients with leprosy, including adults and children aged ≥ 2 years, after excluding leprosy and tuberculosis disease and ensuring no other contraindications. Implement this intervention only in programs that can ensure adequate management of contacts and obtain consent from the index case to disclose their disease.
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