Being affected by the disease once, acts as a lifelong protection for some of the infectious diseases. But, it is not so for tetanus. Give reason.

Explanation

### Step-by-Step Solution:

1. **Understanding Immunity**: When the body is infected by certain infectious diseases, it can develop immunity. This means that the immune system remembers the pathogen (virus or bacteria) and can effectively fight it off if the body encounters it again.

2. **Example of Lifelong Protection**: For many viral infections, such as chickenpox, once a person has been infected, their immune system creates memory cells that recognize the virus. The Varicella Zoster Virus, which causes chickenpox, is remembered by these memory cells, providing lifelong protection against future infections.

3. **Tetanus and Its Cause**: Tetanus, on the other hand, is caused by a bacterium known as Clostridium tetani. Unlike viruses, bacteria can behave differently in terms of how the immune system responds to them.

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