Which one of the following diseases is spread by housefly?

Options

A. Dengue fever
B. Encephalitis
C. Filariasis
D. Typhoid

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which disease is spread by houseflies. It is important to identify the role of houseflies in disease transmission.

2. **Defining a Vector**: A vector is an organism that carries the agent of disease but is not part of the organism's life cycle. In this case, we need to identify if houseflies act as vectors for any of the diseases listed.

3. **Analyzing the Options**:
- **Option A: Dengue Fever**: This disease is spread by the bite of the Aedes mosquito. Therefore, it is not related to houseflies.
- **Option B: Encephalitis**: This disease can be viral or bacterial and is primarily transmitted from animals to humans. Houseflies are not involved in its transmission.
- **Option C: Filariasis**: This disease is also transmitted through mosquito bites. Again, houseflies are not involved.
- **Option D: Typhoid**: This disease is caused by the ingestion of contaminated food and water. Houseflies can contaminate food and water, making them vectors for typhoid.

4. **Conclusion**: After analyzing all the options, it is clear that typhoid is the disease spread by houseflies.

5. **Final Answer**: The disease spread by houseflies is **Typhoid**.

---