Who found poliomyelitis to be viral disease ?

Options

A. Pasteur
B. Popper
C. De Herelle
D. Loeffler and Frosch.

Answer

To answer the question "Who found poliomyelitis to be a viral disease?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Poliomyelitis**: Poliomyelitis, commonly known as polio, is a viral disease that can cause paralysis. It is essential to identify the researchers who made significant contributions to understanding this disease.

2. **Evaluating the Options**: The question provides several names as options. We need to analyze each one to determine who discovered that poliomyelitis is caused by a virus.

3. **Option 1 - Louis Pasteur**: Louis Pasteur was a pioneer in microbiology and is known for developing the pasteurization process. However, he did not discover that poliomyelitis is a viral disease. Thus, this option is incorrect.

4. **Option 2 - Karl Landsteiner and Irwin Popper**: In 1908, Karl Landsteiner and Irwin Popper conducted experiments that demonstrated that poliomyelitis was not caused by bacteria but by a virus. They isolated the poliovirus, confirming that polio is indeed a viral disease. This makes this option correct.

5. **Option 3 - D. Harrelly**: D. Harrelly is known for contributions to applied microbiology but did not specifically work on poliomyelitis. Therefore, this option is incorrect.

6. **Option 4 - Loeffler and Frosch**: Loeffler and Frosch are known for their work on the foot-and-mouth disease virus, not poliomyelitis. Thus, this option is also incorrect.

7. **Conclusion**: After evaluating all options, the correct answer is that Karl Landsteiner and Irwin Popper discovered poliomyelitis to be a viral disease.

### Final Answer:
Karl Landsteiner and Irwin Popper found poliomyelitis to be a viral disease.

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