Q: I am a 30 years old man who got a Widal test done and the results were: TO - 1:20 +, 1:40 +, 1:80 - , 1:160 -; and TH - 1:20 +, 1:40 +, 1:80 -, 1:160 -. Am I having typhoid? I have persistent fever for the last 4 days and the temperature is constantly around 101 degree Celsius. There are no other associated symptoms. Please advise.

A:Widal test will not be able to help in the first 4 days of a fever, even it is due to typhoid. The titre of 1:40 is insignificant in endemic regions. A thorough clinical evaluation along with blood culture and other relevant blood tests would help to diagnose the cause of your fever. Here is some information about the Widal test. Widal test was introduced more than 100 years ago for diagnosis of typhoid fever, despite it being a poor diagnostic test. Widal test gives unreliable diagnostic results in endemic regions for the following reasons:

• There are inherent variabilities of the test.
• It is difficult to establish baseline titres in endemic areas.
• Repeated exposures to Salmonella organisms in endemic regions complicate the issue.
• Cross-reactivities with other organisms influence the result.
• There is poor reproducibility of the test result.

• Absence of infection by S. typhi / S. paratyphi.
• Carrier state.
• Poor antibody production in the patient due to inadequate inoculum of bacterial antigen.
• Technical difficulty or errors in doing the test.
• Previous antibiotic treatment.
• Variability in the preparation of commercial kits.

• Patient has typhoid / paratyphoid fever.
• Previous immunisation with Salmonella antigen.
• Cross-reaction with non-typhoid Salmonella / other organisms.
• Variability and poorly standardised commercial kits.
• Infection with malaria, dengue or other enterobacteriaceae.