Typhidot test to detect IgG & IgM antibodies in typhoid fever
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.
Available from: Dr. Rahul Mitra
- "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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ABSTRACT: For effective management of typhoid, diagnosis of the disease must be done with speed and accuracy. Laboratory diagnosis of typhoid fever requires isolation and identification of Salmonella enterica serotype Typhi. In many areas where the disease is endemic, laboratory capability is limited. Recent advances in molecular immunology have led to the identification of sensitive and specific markers for typhoid fever and technology to manufacture practical and inexpensive kits for their rapid detection. But their limitation paves way to continue to search for the ideal rapid tests to diagnose acute typhoid fever.
Available from: Pavani Kalluri Ram
- "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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ABSTRACT: Tubex and Typhidot, rapid tests for typhoid fever, performed well in evaluations conducted in hospital settings among patients with culture-confirmed typhoid fever. We evaluated these tests in a community clinic in Bangladesh. Blood samples were obtained from 867 febrile patients for culture, Typhidot and Tubex tests. Considering the 43 blood culture-confirmed cases of typhoid fever as typhoid positive and the 24 other confirmed bacteremia cases as typhoid negative, Tubex was 60% sensitive and 58% specific, with 90% positive and 58% negative predictive values (NPVs); Typhidot was 67% sensitive and 54% specific, with 85% positive and 81% NPVs. When blood culture-negative patients and other bacteremia cases together were considered typhoid negative, positive predictive values were only 14% for Tubex and 13% for Typhidot, increasing to only 38% and 20% when restricted to patients with > or = 7 days of fever. We conclude that the value of Tubex and Typhidot tests for typhoid fever diagnosis in a community clinic in urban Bangladesh is low.
Available from: Shanta Dutta
- "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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ABSTRACT: Although typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi, rapid and simple diagnostic serologic tests would be useful in developing countries. We examined the performance of Widal test in a community field site and compared it with Typhidot and Tubex tests for diagnosis of typhoid fever. Blood samples were collected from 6697 patients with fever for > or =3 days for microscopy, culture, and serologic testing and from randomly selected 172 consenting healthy individuals to assess the baseline Widal anti-Typhi O lipopolysaccharide antibody (anti-TO) and anti-Typhi H flagellar antibody (anti-TH) titers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the 3 serologic tests were calculated using culture-confirmed typhoid fever cases as "true positives" and paratyphoid fever and malaria cases as "true negatives". Comparing cutoff values for the Widal test, an anti-TO titer of 1/80 was optimal with 58% sensitivity, 85% specificity, 69% PPV, and 77% NPV. Sensitivity was increased to 67% when the Widal test was done on the 5th day of illness and thereafter. The sensitivity, specificity, PPV, and NPV of Typhidot and Tubex were not better than Widal test. There is a need for more efficient rapid diagnostic test for typhoid fever especially during the acute stage of the disease. Until then, culture remains the method of choice.
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