The organism which spread the disease from and infected person to a healthy person is called ……………….

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term used to describe an organism that transmits a disease from an infected individual to a healthy individual.

2. **Identifying the Key Concepts**:
- The term "organism" refers to any living entity that can carry or spread diseases.
- The process of spreading disease involves transmission from one person to another.

3. **Examples of Disease Transmission**:
- Diseases like HIV and Typhoid are examples of illnesses that can be transmitted from an infected person to a healthy person.
- In the case of Malaria, the disease is caused by a protozoan called Plasmodium, which is transmitted by the female Anopheles mosquito.

4. **Defining the Term**:
- The organism that spreads the disease is specifically referred to as a "Vector."
- Vectors can include various organisms such as mosquitoes, ticks, and fleas that carry pathogens from one host to another.

5. **Final Answer**: The organism which spreads the disease from an infected person to a healthy person is called a **Vector**.

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