Influenza and Other Respiratory Viruses Involved in Severe Acute Respiratory Disease in Northern Italy during the Pandemic and Postpandemic Period (2009–2011)

TLDR

Since the 2009 pandemic, health authorities have urged monitoring severe respiratory infections, and advances such as VIDISCA‑454 aim to reduce diagnostic gaps in severe respiratory disease. The study assessed the proportion of SARI/ARDS cases and deaths attributable to influenza A(H1N1)pdm09 and the contribution of other respiratory viruses in northern Italy during 2009–2011, while also searching for unknown pathogens in undiagnosed cases. Researchers analyzed 206 respiratory samples from SARI/ARDS cases using real‑time RT‑PCR/PCR for influenza and common pathogens, and applied VIDISCA‑454 to samples negative for all known agents. H1N1pdm09 was detected in 58.3 % of specimens with an 11.3 % case‑fatality rate, other viruses accounted for 19.4 % (primarily rhinovirus/enterovirus and H3N2), VIDISCA‑454 identified a measles infection, and about 22 % of SARI/ARDS cases remained undiagnosed.

Abstract

Since 2009 pandemic, international health authorities recommended monitoring severe and complicated cases of respiratory disease, that is, severe acute respiratory infection (SARI) and acute respiratory distress syndrome (ARDS). We evaluated the proportion of SARI/ARDS cases and deaths due to influenza A(H1N1)pdm09 infection and the impact of other respiratory viruses during pandemic and postpandemic period (2009–2011) in northern Italy; additionally we searched for unknown viruses in those cases for which diagnosis remained negative. 206 respiratory samples were collected from SARI/ARDS cases and analyzed by real-time RT-PCR/PCR to investigate influenza viruses and other common respiratory pathogens; also, a virus discovery technique (VIDISCA-454) was applied on those samples tested negative to all pathogens. Influenza A(H1N1)pdm09 virus was detected in 58.3% of specimens, with a case fatality rate of 11.3%. The impact of other respiratory viruses was 19.4%, and the most commonly detected viruses were human rhinovirus/enterovirus and influenza A(H3N2). VIDISCA-454 enabled the identification of one previously undiagnosed measles infection. Nearly 22% of SARI/ARDS cases did not obtain a definite diagnosis. In clinical practice, great efforts should be dedicated to improving the diagnosis of severe respiratory disease; the introduction of innovative molecular technologies, as VIDISCA-454, will certainly help in reducing such “diagnostic gap.”