Typhoid fever is caused by Salmonella typhi and related organisms.

The Widal test detects O (somatic) and H (flagellar) antibodies against Salmonella antigens.

The slide method is a rapid screening technique performed on a glass slide with antigen suspensions.

Clinical uses include:

Screening for typhoid and paratyphoid fever.

Supporting diagnosis in patients with fever, abdominal pain, and gastrointestinal symptoms.

Limitations:

Cross‑reactivity may cause false positives (e.g., malaria, dengue, other infections).

Baseline titers vary by region, so interpretation must consider local endemic values.

Tube Widal test is more quantitative and confirmatory compared to the slide method.

Analyte: Antibodies against Salmonella typhi (O & H antigens) and Salmonella paratyphi (A & B antigens).

Normal Result: Negative (no agglutination).

Abnormal Findings:

Positive agglutination: Suggests typhoid or paratyphoid infection.

Significant titers: Rising antibody levels in paired sera are more diagnostic than a single test.

Clinical Use:

Provides a simple, rapid screening tool for enteric fever.

Helps guide diagnosis and treatment decisions.

Supports infectious disease and general medicine evaluations.