Disease caused by spirochaete bacterium

Options

A. Haemophilus durei
B. Treponema pallidum
C. Chlamydia trachomatis
D. all of the above

Answer

To determine the disease caused by a spirochaete bacterium, we can analyze the options provided:

1. **Haemophilus ducreyi**: This bacterium causes chancroid, which is not caused by a spirochaete. Therefore, this option is incorrect.

2. **Treponema pallidum**: This is the spirochaete bacterium responsible for syphilis. Since syphilis is indeed caused by a spirochaete, this option is correct.

3. **Chlamydia trachomatis**: This bacterium causes chlamydia, which is not a spirochaete but rather a different type of bacteria. Thus, this option is also incorrect.

Based on the analysis of the options, the disease caused by a spirochaete bacterium is:

**Answer: Treponema pallidum (causes syphilis)**

### Step-by-Step Solution:
1. **Identify the options**: The question provides three options of bacteria and the diseases they cause.
2. **Analyze each option**:
- **Option 1**: Haemophilus ducreyi - causes chancroid (not a spirochaete).
- **Option 2**: Treponema pallidum - causes syphilis (is a spirochaete).
- **Option 3**: Chlamydia trachomatis - causes chlamydia (not a spirochaete).
3. **Determine the correct answer**: Since only Treponema pallidum is a spirochaete and is responsible for syphilis, this is the correct answer.