The Widal test is a serological (antibody) blood test used as a screening tool for typhoid fever (also called enteric fever), an infectious disease most commonly caused by Salmonella typhi (and sometimes Salmonella paratyphi). It looks for antibodies your immune system may produce after exposure to these bacteria.

In the Widal test, a blood sample is tested for antibodies that react against specific bacterial components (often reported as “O” and “H” agglutinins). The lab reports results as titers (for example, 1:80, 1:160, 1:320). In general, higher titers or a rising titer on repeat testing can suggest a recent or current infection, while low titers may indicate no infection, early infection, past infection, or prior vaccination/exposure in some regions.

Because background antibody levels can vary by location and because other infections can sometimes cause cross-reactions, the Widal test is best interpreted alongside your symptoms, physical exam, and other tests (such as blood culture or stool culture). A single Widal result alone does not always confirm or rule out typhoid fever.

A clinician may order a Widal test as part of a fever diagnosis when typhoid fever or enteric fever is suspected—particularly in areas where typhoid is common, after travel to higher-risk regions, or when quick screening is needed. It may be considered when culture testing is not readily available or while awaiting culture results.

The test is usually considered in people with symptoms consistent with typhoid/enteric fever, such as:

• Persistent high fever (often lasting several days)
• Headache, weakness, fatigue, body aches
• Abdominal pain, bloating, loss of appetite
• Diarrhea or constipation
• Nausea or vomiting
• Dry cough in some cases
• History of unsafe food or water exposure (street food, unfiltered water, poor sanitation)

It may also be used when there are risk factors for typhoid and other infectious diseases, including:

• Recent travel to regions with higher typhoid rates
• Close contact with someone diagnosed with typhoid
• Living in or visiting settings with limited sanitation or crowding
• Ongoing community outbreaks where public health screening is considered

Important practical notes: antibody tests like Widal may be negative early in the illness (before antibodies rise). Many clinicians prefer or add blood culture (especially early in fever) because it can directly detect the bacteria and help guide antibiotic treatment. Your doctor may also repeat the Widal test to look for a fourfold rise in titer, which is more suggestive of recent infection than a single value.

• Typhoid fever (enteric fever) caused by Salmonella typhi
• Paratyphoid fever caused by Salmonella paratyphi A, B, or C
• Acute febrile illness where typhoid is in the differential diagnosis (evaluation of prolonged fever)
• Gastrointestinal infection related to Salmonella exposure (food- and water-borne illness)

• Supporting timely evaluation of unexplained or persistent fever (fever workup)
• Helping identify possible typhoid/enteric fever to guide appropriate medical treatment
• Reducing risk of complications by prompting earlier clinical follow-up when symptoms suggest an infectious disease
• Supporting travel health decisions and post-travel illness assessment after exposure to unsafe food or water
• Contributing to public health awareness during suspected outbreaks (as part of broader clinical assessment)