Typhoid fever is an important public health problem in developing countries. Effective control of the disease requires detection of cases, definitive treatment and elimination of source of infection, and improvement of public health system. Adequate reporting of cases is often not possible as empirical antibiotic therapy decreases the sensitivity of isolation procedures and serological tests lack specificity in endemic areas. The value of various procedures, namely blood culture, Widal test and polymerase chain reaction (PCR) assay for detection of Salmonella typhi, in the diagnosis of typhoid was evaluated in 60 cases with suspected enteric fever. Sixty percent of the cases had received empirical antibiotic treatment prior to investigations. Seventeen patients were labelled with the diagnosis of typhoid and five had paratyphoid. Thirty-one cases could not be ascribed any diagnosis on the basis of microbiological investigations and the rest seven had various other infectious diseases. The diagnosis of typhoid was arrived at by blood culture3, Widal test11 and PCR assay7. Five of the seven PCR positive cases, none of the culture positive cases and four of the eleven Widal positive cases had received prior antibiotic therapy. Laboratory diagnosis of typhoid remains unsatisfactory in presence of prior antibiotic therapy though PCR seems to be a useful investigation in some of these cases.
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