Typhidot test to detect IgG & IgM antibodies in typhoid fever

Department of Microbiology, Christian Medical College & Hospital, Vellore, India.
The Indian Journal of Medical Research (Impact Factor: 1.4). 08/2002; 116:70-2.
Source: PubMed


As typhoid fever is endemic in India, there is a continuing search for a simple test which can be carried out in small laboratories for an early and rapid diagnosis. We have evaluated the Typhidot test for this purpose.
The Typhidot test was carried out on coded sera according to the manufacturer's instructions. The test was performed on 30 Widal positive sera, 30 sera from blood culture positive patients, 60 Widal negative sera and 30 samples from patients whose blood culture grew Gram negative bacilli (GNB) other than Salmonella Typhi.
Typhidot test was positive for both IgG and IgM in 39 samples, IgM alone in 24 and IgG alone in 2. Of the 30 culture positive samples, 27 were positive by Typhidot. The Typhidot test gave a sensitivity of 100 per cent and specificity of 80 per cent when bacteraemic patients were analysed.
The Typhidot is easy to perform, and requires no special equipment or training of staff for interpretation of results. It will be a useful complementary test to blood culture and the Widal test in the diagnosis of typhoid fever.

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    • "Evaluation of Typhidot® and Typhidot-M®in clinical settings showed that they performed better than the Widal test and the culture method (Bhutta and Mansurali, 1999). An evaluation of Typhidot® in India was 100% sensitive and 80% specific compared to a blood culture as " gold standard " (Jesudason et al., 2002). "
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    • "The test strips are arranged in 2 columns; one column is labeled " M " for dispensing antihuman IgM, and the other column is labeled " G " to dispense antihuman IgG conjugates. According to manufacturers' instructions, an IgM or IgG test strip is considered positive for a test sera when both dots on the respective test strip were as dark as or were darker than their corresponding dots on the positive control sera (Jesudason et al., 2002). The presence of IgM alone or both IgM and IgG was interpreted as a positive test, and absence of both IgM and IgG was interpreted as a negative test (Choo et al., 1994; Ismail, 2006). "
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    • "Elevated levels of anti-O9 IgM antibodies together with typical clinical symptoms of typhoid fever most probably indicate an acute stage of serotype Typhi infection (Feleszko et al., 2004; Tam and Lim, 2003). Both the Tubex and Typhidot tests have been reported to perform well in the diagnosis of typhoid fever, but all these studies have been undertaken in small cohorts of hospitalized patients (House et al., 2001; Jesudason et al., 2002; Olsen et al., 2004; Sherwal et al., 2004). "
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