INCIDENCE OF NON STRUCTURAL PROTEIN (NS1) POSITIVITY & ITS CORRELATION WITH THROMBOCYTE COUNT & SERUM TRANSAMINASE LEVELS (DENGUE EPISODE-2013: A RETROSPECTIVE STUDY)

Abstract

Incidence of NS-1 antigen positivity, Platelet Count, Aspartate  transaminase (AST)  and  Alanine transaminase (ALT) levels were  retrospectively analyzed in Dengue fever, post- dengue episode-2013.  NS-1 was found to be positive in 64.8% cases in present episode.  Significant Serum transaminasemia (raised AST and ALT levels)  & thrombocytopenia  were found in  both NS1 + ve as well as  NS-1 negative groups. Aspartate  transaminase (AST) increase was more marked than alanine transaminase(ALT).  Both AST & ALT showed   linear increase and inverse correlation with the degree of thrombocytopenia in NS1+ve group ; however, linear correlation was  lacking in the NS-1 negative group. Relatively low incidence of NS-1 positivity is indicative of  high probability of dengue re-infection. Marked  thrombocytopenia  associated with significantly raised  serum transaminase level  in NS-1 negative group corroborates the possibility of secondary infection. Thus negative NS-1 antigen test report  does not necessarily exclude the diagnosis of Dengue viral infection. It is recommended that Positive NS1, significant thrombocytopenia and moderately elevated AST levels within 3 – 4 days of onset of disease, may be conjointly used as distinct dengue morbidity triad for distinguishing morbid from benign patients. The criteria would help identify the patients needing hospitalization and intensified cares. However NS1 may not be relevant in endemic zones, migrants, and frequent travellers with high probability for re- infection.