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How does leprosy affect nerves in the skin?

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skin rash caused by Lyme disease — skin disease Visible alterations in the texture of the skin, such as rashes and hives, can be indicative of serious disease. For example, one of the first signs of Lyme disease is a circular rash in a bull's-eye pattern on the skin.

Leprosy, a chronic infectious disease caused by Mycobacterium leprae, affects the peripheral nerves in the skin through two primary pathological reactions.12

In tuberculoid leprosy, the body mounts an intense cellular immune response that crowds into the skin to seal off the bacteria. This reaction involves the nerve fibers ending in the skin and spreads into the main trunks of the involved nerves. This process prevents the transmission of nerve impulses, resulting in a loss of sensation to heat, cold, and touch in the affected area.1

In lepromatous leprosy, the bacteria multiply freely with very little cellular response. While the disease spreads via the nerves, it does not adhere to them in the same destructive manner as the tuberculoid form.1

In both cases, the resulting nerve damage can lead to permanent loss of sensation, paralysis, and tissue degeneration. Because patients cannot feel pain, they are prone to unnoticed injuries, which can lead to severe ulcers, deformity, and the erosion of extremities.123