Diagnostic Performance of Commercially Available Widal Test Kits for the Diagnosis of Typhoid Fever: the Case of One Public Hospital and a Health Center in Addis Ababa, Ethiopia
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Date
2015-11
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Addis Ababa University
Abstract
Background: The causative agent of typhoid fever was first isolated in the late 19th century. The
Widal agglutination test, utilizes a suspension of killed Salmonella Typhi as an antigen, to detect
anti-H and anti-O agglutinins in serum from suspected Salmonella Typhi-infected patients.
Information concerning the utility of Widal test in Ethiopia is limited and studies using multiple
Widal test kits are even far less common.
Objective: The objective of this study was to investigate the diagnostic performance of
commercially available Widal test kits for the diagnosis of typhoid fever in Ethiopia.
Methods: A cross-sectional study was conducted in two governmental health facilities in Addis
Ababa, from October 2014 to February 2015 and a total of 192 typhoid fever suspected patients
participated. Descriptive statistical analysis was conducted on the collected dataset for the
purpose of data exploratory analysis. Different measures of agreements, between the Widal test
kit brands as well as between slide agglutinations and tube titrations were carried out.
Results: Results of the four commercially available Widal test kits under investigation showed
plausibly strong test agreement with each other for slide agglutination methods (kappa statistics
was k= 0.967 for anti-H and k= 0.786 for anti-O antibodies). Also in tube titration method, the
four brands showed strong agreement (k= 0 .875 for anti-H and k= 0.850 for anti-O antibodies).
In contrast, slide agglutination and tube titration agreement results of each brands showed a
relatively lower agreement in anti-H (k <0.40) and a slightly better agreement in anti-O
agglutinins, (k: 0.40–0.68). Among the 190 patient blood samples collected, 4 bacterial isolates
were obtained in which, two of them were S. Typhi.
Conclusion: In this study, the slide agglutination results of the four brands were generally good
and comparable but the tube titration result agreements were lower than the agglutination
agreement results. Also, a significance difference between slide agglutination and tube titration
results of the four brands was found. The current study indicates that although the Widal test can
be used as a good screening method treatment decisions should not be made solely based on
results of slide agglutination.
Key words: Typhoid fever, Salmonella, Widal test kits
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Keywords
Typhoid fever, Salmonella, Widal test kits