Leprosy

 

LEPROSY (HANSEN’S DISEASE)

INTRODUCTION

·        Leprosy is a chronic infectious disease caused by:

• Mycobacterium leprae
• Mycobacterium lepromatosis

·        It is a slowly progressive granulomatous disease affecting:

• Skin
• Peripheral nerves
• Mucous membranes

·        Incubation period: Months to 40 years

·        Commonly affects cooler parts of the body:

• Eyes
• Nose
• Earlobes
• Hands & feet
• Testes

·        Causes:

• Skin lesions
• Nerve damage
• Deformities

·        Transmission:

• Mainly human-to-human (respiratory droplets)
• Rarely from animals (e.g., armadillos)

·        Discovered by Gerhard Armauer Hansen in 1873

·        WHO reduced prevalence with multidrug therapy (MDT), but still a public health issue in some countries.

CLASSIFICATION OF LEPROSY

1. Paucibacillary (PB) / Tuberculoid

• Few lesions (1–5)
• Hypopigmented or erythematous patches
• Loss of sensation (anesthesia)
• Strong immune response

Nerves commonly affected:

• Great auricular nerve
• Ulnar nerve
• Median nerve
• Radial nerve
• Common peroneal nerve
• Posterior tibial nerve
• Sural nerve

2. Multibacillary (MB) / Lepromatous

·        Numerous lesions (>5)

·        Symmetrical distribution

·        Nodules, plaques

·        Thickened dermis

·        May involve:

• Eyes
• Nose
• Testes
• Bones

·        Features:

• Nasal congestion, epistaxis
• High bacterial load

3. Borderline (Dimorphous)

• Most common form
• Intermediate between PB and MB
• Multiple lesions
• Nerve involvement → weakness + sensory loss

PATHOGENESIS

·        Entry: Respiratory tract

·        Bacilli:

• Invade Schwann cells of nerves
• Also found in macrophages

·        Slow multiplication (12–14 days per division)

Immune response determines disease type:

• Strong cell-mediated immunity (CMI) → PB type
• Weak CMI → MB type

Leprosy reactions:

• Type 1 (reversal reaction)
• Type 2 (erythema nodosum leprosum)

SIGNS AND SYMPTOMS

Skin manifestations

• Hypopigmented or reddish patches
• Loss of sensation
• Dry, thickened skin
• Nodules
• Painless ulcers
• Loss of eyebrows/eyelashes

Nerve involvement

• Numbness
• Muscle weakness/paralysis
• Enlarged peripheral nerves
• Loss of sensation → unnoticed injuries

Mucosal involvement

• Stuffy nose
• Nosebleeds

Advanced disease

• Deformities (hands/feet)
• Shortening of fingers/toes
• Chronic ulcers
• Blindness
• Nose deformity

DIAGNOSIS

Clinical diagnosis

• Hypopigmented patch with sensory loss
• Thickened peripheral nerves

Laboratory tests

• Skin smear:
• Acid-fast bacilli (Ziehl–Neelsen stain)
• Skin biopsy

Additional tests:

• Lepromin test
• PCR
• Liver & kidney function tests
• Nerve biopsy

TREATMENT (WHO MDT)

Paucibacillary (PB)

• Rifampicin
• Dapsone
• Duration: 6–12 months

Multibacillary (MB)

• Rifampicin
• Dapsone
• Clofazimine
• Duration: 12 months or more

Single lesion (WHO recommendation)

• Single-dose therapy:
• Rifampicin + Ofloxacin + Minocycline

Other management

• Steroids → for inflammation & nerve damage
• Early treatment prevents disability

COMPLICATIONS

• Blindness / glaucoma
• Facial deformities
• Infertility (in males)
• Kidney damage
• Claw hand deformity
• Chronic ulcers
• Permanent nerve damage

PREVENTION

·        Early diagnosis and treatment

·        Contact tracing

·        Public awareness

·        Chemoprophylaxis:

• Single-dose rifampicin for close contacts

·        Vaccine:

• No specific vaccine
• BCG gives partial protection

PATHOPHYSIOLOGY (SUMMARY)

·        Spread via nasal droplets

·        Affects:

• Skin
• Peripheral nerves
• Upper respiratory mucosa
• Eyes
• Testes

·        Key mechanism:

• Nerve damage → sensory loss → deformities