What are communicable diseases?

Explanation

**Step-by-Step Solution:**

1. **Definition of Communicable Diseases**: Communicable diseases are illnesses that can be transmitted from one person to another. This transmission can occur through various means.

2. **Modes of Transmission**: These diseases can be spread through different mediums, such as:
- **Air**: For instance, diseases like the common cold can be spread when an infected person coughs or sneezes, releasing droplets into the air.
- **Water**: Some diseases, like typhoid, are transmitted through contaminated water or food.
- **Body Contact**: Certain skin diseases caused by fungi can spread through direct contact with an infected person or by sharing personal items like towels.
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