What is Hansen's disease?

Hansen's Disease (Leprosy): A Comprehensive Overview

Hansen's disease (leprosy) is a chronic bacterial infection caused by Mycobacterium leprae that primarily affects the skin, peripheral nerves, and mucosa of the upper airway, resulting in potentially severe disfigurement and disability if left untreated. 1

Clinical Presentation

Hansen's disease manifests in several clinical forms based on the host's immune response to M. leprae:

• Tuberculoid (paucibacillary): Characterized by one or a few well-demarcated, hypopigmented, and anesthetic skin lesions with active spreading edges and clearing centers; peripheral nerve swelling may occur 1

• Lepromatous (multibacillary): Presents with multiple erythematous papules and nodules or infiltration of the face, hands, and feet with bilateral and symmetrical distribution that progresses to skin thickening 1

• Borderline (dimorphous): Shows skin lesions with features of both tuberculoid and lepromatous forms 1

• Indeterminate: Early disease with hypopigmented macules without developed tuberculoid or lepromatous features 1

Affected Systems

Hansen's disease typically involves:

• Skin: Various lesions depending on disease form 1
• Peripheral nerves: Leading to numbness, weakness, and sensory loss 2, 3
• Eyes: Can cause eye pain or vision loss 2
• Upper respiratory mucosa: Involvement can lead to nasal symptoms 1

Epidemiology

• Hansen's disease remains an important public health problem globally 2
• In the United States, approximately 150 new cases are reported annually 4
• The nine-banded armadillo is the major animal reservoir in the United States 2, 5
• Incidence in the US has declined from 0.52 to 0.43 per million when comparing 1994-1996 to 2009-2011 6
• Foreign-born persons have higher rates than US-born individuals 6

Diagnosis

Diagnosis is confirmed by:

• Laboratory criteria: Demonstration of acid-fast bacilli in skin or dermal nerve, obtained from full-thickness skin biopsy of a lepromatous lesion 1
• Clinical presentation: Compatible signs and symptoms including skin lesions and neurological findings 1, 2

Treatment

Modern treatment typically consists of:

• Multidrug therapy including combinations of:

  • Dapsone and rifampin for paucibacillary disease 2, 5
  • Dapsone, rifampin, and clofazimine for multibacillary disease 2, 5
  • Alternative agents include moxifloxacin, ofloxacin, minocycline, and clarithromycin 2

• Management of immunologic reactions:

  • Type 1 (reversal) reactions and Type 2 (erythema nodosum leprosum) reactions may occur before, during, or after treatment 2
  • Treatment options include corticosteroids, thalidomide, pentoxifylline, TNF inhibitors, and T-cell inhibitors 2
  • Antibacterial therapy should usually be continued during these reactions 2

Complications and Prognosis

• Without treatment, Hansen's disease can progress to severe disability with nerve damage, tissue destruction, and functional loss 2, 6
• Early diagnosis and prompt treatment dramatically reduce complications 2, 5
• Delayed diagnosis is more common among foreign-born persons in the US 6

Prevention

• Early detection and treatment are crucial to preventing irreversible damage 5
• Contact tracing and prophylaxis for close contacts 5
• Community awareness and education 5

Hansen's disease is curable with appropriate antimicrobial therapy, but early recognition is essential to prevent permanent nerve damage and disability. Clinicians throughout the United States should be familiar with its signs and symptoms, as cases continue to occur domestically 6.