Comparative study of immunochromatographic assay (IgM) and widal test for early diagnosis of typhoid fever

Typhoid fever is a severe systemic infection endemic in many developing countries, including Bangladesh. Present study evaluated immunochromatographic test (ICT) and Widal test in the early diagnosis of typhoid fever cases. The study was carried out in the department of Microbiology, Mymensingh Medical College, Mymensingh between July, 2010 and June, 2011, including 200 individuals of different age and sex. Of them, 150 were clinically suspected cases of typhoid fever and 50 age-sex matched controls. Among 150 blood samples from the suspected cases 106(70.7%) were positive for IgM of Salmonella typhi by ICT and 67(44.7%) were positive by Widal test. Whereas, among the 50 controls 4(8%) were positive by ICT and 6(12%) were positive by Widal test. The sensitivity, specificity, positive and negative predictive value of the ICT was found as 83.3%, 92.00%, 91.9% and 83.6% respectively. On the other hand corresponding values for Widal test were of 44.4%, 88%, 80% and 59.5% respectively. Thus, The ICT (IgM) is better alternative to Widal test for early and accurate diagnosis of typhoid fever. The ICT (IgM) is rapid, easy to perform, applicable for field use and highly sensitive and specific for detection of antibodies in patients with typhoid fever.