Typhoid fever is one of the infectious human diseases. Outbreaks of typhoid fever caused
by Salmonella typhi remains a serious health problem worldwide. There are a number of
tests available presently, from molecular to immunological and biochemical to
microbiological. However, misdiagnosis is usually experienced since most health care
facilities use only Widal test without confirmation of results with a second test method.
This study aimed at evaluating the performance of Widal test and stool culture in the
laboratory diagnosis of typhoid fever using blood culture as gold standard. Presenting
patients aged between 5 to 82 years with symptoms clinically suspected to be of typhoid
fever visiting Chuka General Hospital for a period of eighteen months were recruited for
the study. Informed consent of volunteers and guardians were obtained. Serum samples
from a total of 126 patients were subjected to Widal agglutination tests. Blood and stool
samples from the same individuals were analyzed for typhoid fever infection using blood
and stool cultures respectively. Serotyping was performed using agglutination with
Salmonella O, H and Vi antisera. In Widal agglutination test, titre values from 1:160 and
above were regarded as significant and therefore positive for the Salmonella antigen.
Isolation of Salmonella typhi from stool and blood culture indicated an infection. Raw
data were entered into Microsoft excel and analyzed using statistical package for social
sciences (SPSS). Analysis involved computation of descriptive statistics such as
frequencies, means and standard deviations. Comparison of categorical data was made
using Chi square or fisher’s exact test, as appropriate. The confidence intervals for
sensitivity and specificity were computed using the Wilson’s score method. A P value ≤
0.05 was considered statistically significant. The sensitivity, specificity, positive
predictive value (PPV) and negative predictive value (NPV) for Widal test and stool
culture were calculated. The total number of patients positive for typhoid fever based on
Widal test were 70 (55.6%). The prevalence of typhoid fever was 42.9% and 15.1%
based on the findings from stool and blood culture respectively. Widal test recorded
73.7% sensitivity, 47.7% specificity, 20% positive predictive value and 91.1% negative
predictive value. Stool culture showed 84.2% sensitivity, 64.5% specificity, 29.6%
positive predictive value and 95.8% negative predictive value. These results demonstrate
that Widal test is not very reliable for diagnosis of typhoid fever since false positive and
false negative results are common. The low PPV means that Widal test could only be
useful for excluding the disease from the population hence health care personnel should
not totally depend on this test alone for diagnosis of enteric fever but should use other
diagnostic methods to differentiate Salmonella infection from other infection. There is
therefore, an urgent need to develop a rapid, highly sensitive and cheap diagnostic tool
for diagnosis of typhoid fever.
Edu, F (2021). Performance Of Widal Test And Stool Culture As Diagnostic Methods For Salmonella Typhi Infection In Chuka General Hospital, Tharaka Nithi County. Afribary.com: Retrieved June 18, 2021, from https://afribary.com/works/performance-of-widal-test-and-stool-culture-as-diagnostic-methods-for-salmonella-typhi-infection-in-chuka-general-hospital-tharaka-nithi-county
Frontiers, Edu. "Performance Of Widal Test And Stool Culture As Diagnostic Methods For Salmonella Typhi Infection In Chuka General Hospital, Tharaka Nithi County" Afribary.com. Afribary.com, 04 Jun. 2021, https://afribary.com/works/performance-of-widal-test-and-stool-culture-as-diagnostic-methods-for-salmonella-typhi-infection-in-chuka-general-hospital-tharaka-nithi-county . Accessed 18 Jun. 2021.
Frontiers, Edu. "Performance Of Widal Test And Stool Culture As Diagnostic Methods For Salmonella Typhi Infection In Chuka General Hospital, Tharaka Nithi County". Afribary.com, Afribary.com, 04 Jun. 2021. Web. 18 Jun. 2021. < https://afribary.com/works/performance-of-widal-test-and-stool-culture-as-diagnostic-methods-for-salmonella-typhi-infection-in-chuka-general-hospital-tharaka-nithi-county >.
Frontiers, Edu. "Performance Of Widal Test And Stool Culture As Diagnostic Methods For Salmonella Typhi Infection In Chuka General Hospital, Tharaka Nithi County" Afribary.com (2021). Accessed June 18, 2021. https://afribary.com/works/performance-of-widal-test-and-stool-culture-as-diagnostic-methods-for-salmonella-typhi-infection-in-chuka-general-hospital-tharaka-nithi-county