Performance of Typhoid Diagnostic Tests among Patients in Ga West Municipality, Ghana
Michael Oppong Yeboah *
Akramaman Health Centre, Ga West Municipal Health Directorate, Amasaman, Accra, Ghana.
Frank Bediako Agyei
Department of Nursing and Midwifery, University of Skills Training and Entrepreneurial Development, Mampong, Ghana.
Omosive Maduka
Department of Preventive and Social Medicine, University of Port Harcourt, Rivers State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Accurate diagnosis of typhoid fever is challenging where febrile illnesses have overlapping symptoms. This study compared four laboratory tests among patients in Ga West Municipality, Ghana.
Methods: In a comparative cross-sectional study, 284 eligible febrile patients attending seven health facilities underwent Widal testing, Typhidot IgM rapid diagnostic testing (RDT), blood polymerase chain reaction (PCR), stool PCR, and blood culture. Blood culture was used as the reference standard. Sensitivity, specificity, predictive values, and accuracy were estimated relative to culture; diagnostic agreement and paired classifications were assessed using Cohen's kappa and McNemar's test.
Results: Eight of 284 patients (2.8%) were blood-culture positive. Observed positivity was 65.8% for the Widal test, 48.9% for both RDT IgM and blood PCR, and 18.7% for stool PCR. Each index test identified the eight culture-positive patients (observed sensitivity, 100%), although this estimate was based on few confirmed cases. Stool PCR had the highest specificity (83.7%) and accuracy (84.2%) relative to blood culture. Corresponding values were 52.5% and 53.9% for both RDT IgM and blood PCR, and 35.1% and 37.0% for the Widal test. RDT IgM and blood PCR classified all patients identically (κ = 1.000).
Conclusion: Stool PCR showed the highest specificity and accuracy against blood culture in this sample, but stool positivity does not necessarily establish active systemic infection. The small culture-positive group and imperfect sensitivity of blood culture limit definitive comparisons. Further validation is needed before recommending changes in routine diagnostic practice.
Keywords: Typhoid fever, Widal test, polymerase chain reaction, rapid diagnostic test