Shelke V, Potdar V, Chadha M, Kolhapure R, Prasad S, Jain P and Basu A*
The rapid emergence of a novel influenza A/ H1N1 virus designated pH1N1 2009 caused one of the fastest pandemics of the twentieth century. The rapid development of an accurate detection test for this pandemic virus using reverse transcription-real time polymerase chain reaction (rRT-PCR) helped in timely diagnosis. In India this pandemic peaked between August to October 2009.The r-RT PCR for pH1N1 2009 was the main diagnostic test used on throat/nasopharyngeal swabs in all cases. While in majority of the cases this test provided reliable confirmation of the virus, it gave negative or indeterminate results in a subset of cases meeting the standard case definition for the pandemic infection and negative for seasonal flu. In the present study we examined 4 such fatal cases where microscopic pathology of the lung was consistent with viral bronchopneumonia for the presence of pH1N1 2009 using r-RT PCR on nucleic acid extracted from the paraffin sections that showed presence of viral antigens by immunohistochemistry. In all 4 cases pH1N1 sequences could be identified. These findings therefore emphasize the important role of microscopic pathology techniques in conjunction with molecular tools in the diagnostic confirmation of novel agents during a public health emergency.