Which test is used to diagnose typhoid?

BSF Staff Nurse - 2015

Medical Surgical Nursing

Easy

Appeared in: BSF Staff Nurse - 2015

Explanation

The Widal test is a classic serological agglutination assay specifically used to aid in the diagnosis of typhoid (enteric) fever.
It functions by detecting the presence of agglutinating antibodies in the patient's serum against the O (somatic) and H (flagellar) antigens of the bacterium Salmonella typhi.
Antibody titers typically begin to rise by the end of the first week of illness, making the test most useful from the second week onwards.
A four-fold or greater increase in antibody titers between two samples taken about 7-10 days apart is considered strong evidence of an active infection.

Option A: ELISA is a general laboratory method, not a specific named test for typhoid in the context of the other options. While modern ELISA-based kits for typhoid (like Typhidot) exist, 'Widal test' refers to the specific, traditional agglutination test.
Option B: The Western blot is a highly specific confirmatory test, not a primary diagnostic tool for typhoid fever. It is used to confirm positive screening tests for other infections, most notably HIV.
Option D: The TOTHRA test is not a recognized or standard medical diagnostic procedure for typhoid fever or any other common disease. It is an incorrect option.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Diagnosis of Typhoid Fever as background academic context rather than a clinical decision trigger.
Nurses must understand that the Widal test has significant limitations. A negative result early in the illness does not rule out typhoid, and a positive result must be interpreted cautiously due to potential false positives from vaccination or past infections.
The gold standard for diagnosing typhoid fever, especially in the first week, is a blood culture. The Widal test is a supplementary test that becomes more reliable as the illness progresses into the second week.
Patient education is crucial. A nurse may need to explain to the patient or family why a second blood sample is needed a week later to look for a rising antibody titer, which provides more conclusive evidence than a single test.

How to Approach the Question

Analyze the question: The question asks to identify the specific test used to diagnose typhoid fever from the given options.
Evaluate the options based on medical knowledge. Recall or deduce the primary application of each test.
Option A (ELISA) is a broad technique, not a specific test name like Widal.
Option B (Western blot) is famously associated with confirming HIV, not diagnosing typhoid.
Option C (WIDAL test) is the classic, historically significant serological test for typhoid fever.
Option D (TOTHRA test) is not a standard medical term, making it an unlikely correct answer.

Concept Tested & Keywords

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