Typhi Dot in Dehradun

What is a Typhi Dot?

Typhidot detects IgM and IgG antibodies against a specific outer membrane protein of Salmonella typhi, the bacterium causing typhoid fever. It was developed to address the well-known shortcomings of the older Widal test, and it does so partly: it becomes positive earlier, from around day two or three of fever compared with the second week for Widal, and IgM positivity suggests a current infection while IgG alone more often reflects past exposure or vaccination. In an endemic country that distinction matters, because a large proportion of the population carries background antibodies from previous exposure, and a test that cannot separate old from new is of limited use. Typhidot is nonetheless a rapid antibody card, not a definitive answer. False positives occur with other Salmonella infections, with malaria and dengue, and in people with prior typhoid, and false negatives occur very early or in those already on antibiotics. Blood culture remains the reference standard, because it grows the organism itself and provides antibiotic sensitivities, which matters increasingly given rising drug resistance.

Why take this test?

Typhidot is advised for a fever lasting more than about three days, particularly one that climbs in a stepwise fashion, with headache, abdominal discomfort, marked malaise, loss of appetite and either constipation or loose stools, during or after the monsoon in Dehradun and the Doon valley where typhoid is transmitted through contaminated food and water. It is used when a rapid indication is wanted while blood culture is pending, and it is more informative than Widal early in the illness. It should be interpreted alongside a Complete Blood Count, since typhoid characteristically produces a normal or low white cell count rather than the raised count of most bacterial infections, and alongside tests for dengue and malaria, which present similarly in the same season. Where typhoid is genuinely suspected, ask your doctor about blood culture as well, because it identifies the organism and its resistance pattern, which increasingly determines whether the first antibiotic chosen will work.

• Fever lasting more than about three days in or after the monsoon
• Stepwise rising fever with headache and marked malaise
• Abdominal discomfort with constipation or loose stools
• Where a rapid result is wanted while blood culture is pending
• Alongside dengue and malaria testing in an undifferentiated fever
• Alongside a Complete Blood Count, which shows a characteristic pattern

Normal reference ranges

Ranges are indicative for adults. Your report carries the lab-specific reference range and is reviewed by a LabONE pathologist; always interpret results with your doctor.

FAQs: Typhi Dot in Dehradun