Retrospective Audit of the Widal Test for Diagnosis of Typhoid Fever in Pediatric Patients in an Endemic Region
Dr. Preena Bhalla,
Director Professor, Department of Microbiology, Maulana Azad Medical College,
Bahadur Shah Zafar Marg, New Delhi-110002, India.
Phone: +91-9810677106, Email: email@example.com
Introduction:Although typhoid fever is confirmed by culture of Salmonella Typhi , Widal test is widely used in India but little information exists about its reliability.
Materials and Methods:We examined the performance of Widal test in our hospital for diagnosis of typhoid fever in children. Hundred consecutive pediatric in-patients for whom, the Widal test was requested were grouped into four categories: widal positive and clinically consistent with typhoid fever (Group 1; n=42), widal negative but clinically consistent (Group 2, n=12), widal positive but not clinically consistent (Group 3, n=12) and widal negative and also not clinically consistent (Group 4, n=34). The results were analyzed by the test performance criteria, namely, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) using culture-confirmed typhoid fever cases as the â€śtrue positivesâ€ť.
Results:We found that 7/100 patients had culture-proven typhoid fever. Using a cut off = 50 for O agglutinins or = 100 for H agglutinins, the Widal test gave a sensitivity of 71.43%, specificity of 47.31%, and a positive predictive value of 09.25% and a negative predictive value of 95.65%.
Conclusion:The Widal test is an easy, inexpensive and relatively non-invasive but is not reliable in our set up because of a low PPV. There is a need for a more efficient rapid diagnostic test for typhoid fever.