Which of the following diseases is not transmitted by houseflies ?

Options

A. Cholera
B. Typhoid
C. Dysentery
D. Yallow fever

Answer

To determine which disease is not transmitted by houseflies from the given options, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Diseases Listed**: The options provided are:
- A. Cholera
- B. Typhoid
- C. Dysentery
- D. Yellow fever

2. **Research Disease Transmission**: We need to analyze how each of these diseases is transmitted:
- **Cholera**: This is an infectious disease caused by the bacterium *Vibrio cholerae*. It is primarily transmitted through contaminated water and food. However, houseflies can also carry the bacteria from feces to food, making it a potential vector.
- **Typhoid**: This disease is caused by the bacterium *Salmonella typhi*. Similar to cholera, it is transmitted through contaminated food and water, and houseflies can spread it by contaminating food with fecal matter.
- **Dysentery**: This refers to inflammation of the intestines, often caused by bacteria such as *Shigella*. Houseflies can also spread dysentery by contaminating food with fecal matter.
- **Yellow fever**: This is an acute viral hemorrhagic disease caused by the yellow fever virus. It is transmitted by infected mosquitoes, not houseflies.

3. **Conclusion**: Based on the transmission methods:
- Cholera, Typhoid, and Dysentery are diseases that can be transmitted by houseflies.
- Yellow fever is not transmitted by houseflies; it is transmitted by mosquitoes.

4. **Final Answer**: Therefore, the disease that is not transmitted by houseflies is **Option D: Yellow fever**.