AIM OF THE STUDY:
To analyse the efficacy of Immunochromatography with ELISA for detection of Dengue parameters (NS1 antigen, IgM and IgG antibodies) in Dengue suspected cases.
MATERIALS AND METHODS:
A total of 100 blood samples obtained from adults with fever >4 days presenting with thrombocytopaenia (<1,00,000) were taken for the study from the Department of Medicine, Government Medical College Hospital, Tirunelveli after obtaining informed written consent. The samples were tested by Rapid Immunochromatography (ICT) and ELISA methods for NS1 Ag, IgM and IgG Ab and the results were evaluated for efficacy.
RESULTS:
Out of 100 adults tested by rapid ICT, 38% were positive for Dengue infection (NS1 antigen, IgM and IgG antibodies) in the serum sample. The same samples were tested by ELISA (Positive for any one of the three parameters) the positivity was found to be 59%. 37 samples positive by ICT were positive by ELISA also. Rapid ICT had a sensitivity of 87.5%, Specificity of 98.8% for NS1 antigen when evaluated against NS1 antigen.
ELISA as gold standard. Rapid ICT had a very low sensitivity of 28.6% and 47.1% and an excellent specificity of 98% and 100% for IgM and IgG antibody detection when evaluated against MAC ELISA and GAC ELISA as gold standard respectively.13.6% showed primary infection and 64.4% showed secondary infection.
CONCLUSION:
Out of the total 100 cases studied, the rapid immunochromatography test has very less sensitivity and specificity is satisfactory .All samples should be subjected to both antigen(NS1) and antibody (IgM and IgG) testing to increase the positivity rate and to prevent the positive cases being missed. Cases with higher degrees of suspicion are to be subjected to diagnostic tests with higher sensitivity & specificity like ELISA and PCR. The commercially available rapid immunochromatographic test device can be used as a screening device during Dengue outbreaks. It should not be used as a standalone device for diagnosis of Dengue. Further molecular studies are essential to know the accurate information of Dengue serotypes which will be helpful in formulating vaccines in future
