Lymphoid leucosis is a poultry disease caused by

Options

A. Virus
B. Fungi
C. Helminths
D. Bacteria

Answer

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about lymphoid leucosis, which is a disease affecting poultry, particularly chickens.

2. **Understand the Nature of the Disease**: Lymphoid leucosis is classified as a neoplastic disease. This means it is related to the formation of tumors.

3. **Determine the Cause of the Disease**: The disease is caused by an infection. In this case, it is important to identify what type of pathogen is responsible for the infection.

4. **Consider the Options**: The options provided are virus, fungi, helminths, and bacteria. Since lymphoid leucosis is a viral disease, we need to focus on the viral option.

5. **Identify the Specific Virus**: The specific virus responsible for lymphoid leucosis is the avian leucosis virus, which is a type of retrovirus.

6. **Conclude the Answer**: Based on the information gathered, lymphoid leucosis is caused by a virus, specifically the avian leucosis virus.

**Final Answer**: Lymphoid leucosis is a poultry disease caused by a virus (avian leucosis virus).

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