Epidemiology of Leprosy

Introduction

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.

Mechanisms of Nerve Damage

Nerve damage in leprosy occurs due to the invasion of Schwann cells by M. leprae, leading to demyelination and axonal degeneration. The immune response against the bacteria further exacerbates neural inflammation.

Immune Response Variations

The immune response to M. leprae varies significantly among individuals, influencing disease progression. The two main forms of leprosy—tuberculoid and lepromatous—reflect these differences in immune reactivity.

Progression of Different Clinical Forms

• Tuberculoid Leprosy: Characterized by strong cell-mediated immunity, leading to localized lesions and nerve involvement.
• Lepromatous Leprosy: Associated with a weak immune response, resulting in widespread skin lesions, nerve damage, and systemic involvement.

Global Epidemiology

Despite efforts to eliminate leprosy, it remains endemic in several countries, particularly in South Asia, Africa, and South America. Early diagnosis and multidrug therapy (MDT) have been crucial in controlling the disease.