Leprosy (Hansen's Disease)

Leprosy is a chronic infectious disease caused by the bacterium Mycobacterium leprae, also known as Hansen’s disease. It primarily affects the skin, peripheral nerves, mucosa of the upper respiratory tract, and eyes. Throughout history, leprosy has been associated with stigma and social exclusion, but thanks to modern medicine it can now be effectively treated. Nevertheless, it continues to hold significant public health importance, particularly in developing countries.

Etiology and Transmission Routes of Leprosy

The causative agent, Mycobacterium leprae, is an acid-fast bacterium with a slow replication rate. It is found primarily in humans and armadillos, and occasionally in other animals. Leprosy is a transmissible disease between humans, but its infectiousness is low. Transmission typically occurs through prolonged and close contact.

Transmission Routes

1. Respiratory Route: Infection occurs through contact with nasal and oral secretions from infected individuals.
2. Dermal Route: Rarely, transmission may occur through direct contact with skin lesions of infected persons.
3. Mother to Child: Very rarely, transmission from mother to child can occur.

Clinical Manifestations of Leprosy

Leprosy can present in different forms depending on clinical findings and the host’s immune response. The clinical spectrum ranges from tuberculoid leprosy (mild form) to lepromatous leprosy (severe form), with intermediate forms existing between these two extremes.

Tuberculoid Leprosy

• Occurs when the immune system is strong.
• Characterized by well-defined, hypopigmented skin lesions and nerve involvement.
• Lesions are usually few in number and accompanied by loss of sensation.
• Low infectiousness.

Lepromatous Leprosy

• Occurs when the immune system is weak.
• Features widespread nodules, plaques, and hypopigmented lesions on the skin.
• May affect the nasal mucosa, eyes, and internal organs.
• Higher infectiousness.

Borderline Leprosy

• Shows a clinical picture intermediate between tuberculoid and lepromatous leprosy.
• The number and severity of lesions vary.

Diagnosis and Treatment of Leprosy

The diagnosis of leprosy is confirmed by clinical findings and laboratory tests. Detection of acid-fast bacilli through microscopic examination of skin lesion samples or biopsy can establish the diagnosis.

Treatment Methods

Leprosy can be effectively treated with multidrug therapy (MDT). The treatment regimen recommended by the World Health Organization (WHO) includes:

1. Dapsone: The cornerstone drug, used in all forms of leprosy.
2. Rifampicin: Possesses strong antibacterial activity.
3. Clarithromycin: Particularly used in lepromatous leprosy.

The duration of treatment varies between 6 and 12 months depending on the form of the disease. Early diagnosis and treatment are critical to prevent permanent nerve damage and disabilities.

Complications of Leprosy

If left untreated, leprosy can lead to serious complications, including:

1. Nerve Damage: Involvement of peripheral nerves may result in loss of sensation, muscle weakness, and paralysis.
2. Ocular Involvement: Severe eye complications that can progress to blindness.
3. Deformities: Structural abnormalities of the hands, feet, and face due to nerve damage and recurrent infections.
4. Social Stigma: The disease can lead to social stigma and exclusion within communities.

Prevention of Leprosy

Prevention of leprosy is possible through early diagnosis, effective treatment, and community education. Additionally, treating infected individuals plays a key role in reducing transmission.