The chemical test that is used for diagnosis of typhoid is

Options

A. ELISA-Test
B. ESR-Test
C. PCR-Test
D. Widal-Test

Explanation

### Step-by-Step Solution:

1. **Understanding Typhoid**:
- Typhoid is an infectious disease caused by the bacterium *Salmonella typhi*. It is often transmitted through contaminated food and water.

2. **Identifying the Tests**:
- The question provides four options for the chemical test used in diagnosing typhoid: ELISA test, ESR, PCR, and VDAL test.

3. **Analyzing Each Option**:
- **ELISA Test**: This test is primarily used for detecting antibodies or antigens in various infections but is not specifically used for typhoid.
- **ESR (Erythrocyte Sedimentation Rate)**: This is a non-specific test that measures inflammation in the body but does not diagnose typhoid.
- **PCR (Polymerase Chain Reaction)**: This is a molecular technique used to detect the genetic material of pathogens but is not a chemical test specifically for typhoid.
- **VDAL Test**: This is a serological test used to detect antibodies against *Salmonella typhi* in the patient's serum.

4. **Conclusion**:
- The correct answer is the VDAL test, which is specifically designed to diagnose typhoid by detecting the presence of antibodies against *Salmonella typhi* in the blood.

### Final Answer:
The chemical test that is used for the diagnosis of typhoid is the **VDAL test**.

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