Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by the bacterium Mycobacterium leprae. It primarily affects the skin, peripheral nerves, upper respiratory tract, and eyes, leading to progressive nerve damage and skin lesions. Contrary to common myths, leprosy is not highly contagious and can be treated effectively with antibiotics.
Causes and Transmission of Leprosy
Leprosy is caused by Mycobacterium leprae, a slow-growing bacillus that primarily infects the nerves and skin. The exact transmission method is not fully understood, but the disease is believed to spread through:
- Prolonged close contact with untreated individuals.
- Respiratory droplets from an infected person’s sneezing or coughing.
- Environmental exposure in some cases, including contact with armadillos (which can carry M. leprae in certain regions).
Leprosy is not transmitted through casual contact, such as shaking hands, sharing meals, or touching common surfaces.
Types of Leprosy
Leprosy is classified based on the immune response and severity:
1. Tuberculoid Leprosy (Paucibacillary Leprosy)
- Mild form of leprosy.
- Characterized by one or a few well-defined skin lesions.
- Causes nerve thickening and loss of sensation in affected areas.
- The immune response is strong, keeping bacterial growth limited.
2. Lepromatous Leprosy (Multibacillary Leprosy)
- Severe form with widespread skin lesions, nodules, and thickened skin.
- High bacterial load, leading to progressive nerve damage and disfigurement.
- Affected individuals may experience blindness, loss of eyebrows, and nasal deformities.
3. Borderline Leprosy
- Intermediate between tuberculoid and lepromatous leprosy.
- Patients may develop unstable symptoms, fluctuating between the two extremes.
Classification Based on WHO Guidelines
- Paucibacillary (PB) Leprosy: 5 or fewer skin lesions, with no detectable bacteria in skin smears.
- Multibacillary (MB) Leprosy: More than 5 skin lesions, with bacteria detected in skin smears.
Symptoms of Leprosy
Leprosy manifests with gradual onset and symptoms can take years to appear due to the slow replication of M. leprae (incubation period: 2-10 years). Key symptoms include:
- Skin Lesions – Pale or reddish patches with loss of sensation.
- Nerve Damage – Numbness, tingling, or muscle weakness in affected areas.
- Loss of Eyebrows/Eyelashes – A hallmark sign in advanced cases.
- Thickened Peripheral Nerves – Resulting in sensory loss and muscle paralysis.
- Ulcers and Infections – Chronic wounds due to lack of sensation.
- Facial Disfigurement – Advanced cases may develop collapsed nose bridges and clawed hands.
Diagnosis of Leprosy
Early diagnosis is crucial to prevent nerve damage and disability. Methods include:
- Clinical Examination – Checking for characteristic skin lesions and sensory loss.
- Skin Smear Test – Staining skin samples to detect M. leprae bacteria.
- Skin Biopsy – Microscopic analysis of infected tissue.
- Lepromin Test – Determines immune response but does not confirm active infection.
- PCR (Polymerase Chain Reaction) – Detects bacterial DNA in early cases.
Treatment of Leprosy
Leprosy is curable with multidrug therapy (MDT), a regimen recommended by the World Health Organization (WHO). Treatment duration depends on the type:
- Paucibacillary Leprosy (PB) – 6 months of Rifampicin and Dapsone.
- Multibacillary Leprosy (MB) – 12–24 months of Rifampicin, Dapsone, and Clofazimine.
Medications Used in MDT
- Rifampicin – Kills M. leprae and is taken once monthly.
- Dapsone – Inhibits bacterial growth and is taken daily.
- Clofazimine – An anti-inflammatory agent used for severe cases.
Early treatment prevents disabilities and reduces transmission.
Complications of Untreated Leprosy
If left untreated, leprosy can lead to severe disabilities and deformities, including:
- Paralysis and Muscle Atrophy – Due to nerve damage.
- Claw Hand and Foot Drop – Resulting from muscle weakness.
- Blindness – Due to corneal damage and chronic infections.
- Nasal Collapse – Bone loss leading to facial deformities.
- Recurrent Ulcers and Secondary Infections – Causing severe tissue damage.
Prevention and Control of Leprosy
- Early Detection & Treatment – Prompt MDT can prevent spread and disability.
- BCG Vaccine – Offers partial protection against M. leprae.
- Public Awareness & Stigma Reduction – Education helps combat myths and discrimination.
- Contact Tracing & Prophylactic Treatment – Close contacts of leprosy patients may receive single-dose Rifampicin (SDR) to prevent infection.
Global Impact and Epidemiology
Leprosy remains endemic in regions with poor healthcare access, particularly in:
- India, Brazil, Indonesia, Nigeria, and Bangladesh – Countries with the highest leprosy burden.
- Annual Cases: Over 200,000 new cases reported worldwide.
- Elimination Efforts: WHO aims for zero disability in new pediatric cases and improved early detection.
Future Research and Advancements
Ongoing research focuses on:
- Better Diagnostic Tools – Faster, more sensitive blood tests for early detection.
- New Drug Combinations – Reducing treatment duration and side effects.
- Genetic Studies – Understanding host susceptibility to leprosy.
Leprosy, though historically feared, is curable and can be effectively managed with early detection and multidrug therapy. Raising awareness, improving access to healthcare, and reducing stigma are essential to achieving the global goal of leprosy elimination. Continued research and public health efforts will help eradicate this disease and improve the quality of life for affected individuals.
