Prolonged Viral Shedding of Influenza Virus: Which Definition?Macé M Schuurmans1* and Nicolas J Mueller2
- *Corresponding Author:
- Macé M Schuurmans
Division of Pulmonary Medicine, University Hospital Zurich
Raemistrasse 100, 8091 Zurich, Switzerland
E-mail: [email protected]
Received date: November 07, 2014; Accepted date: November 25, 2014; Published date: November 27, 2014
Citation: Schuurmans MM, Mueller NJ (2014) Prolonged Viral Shedding of Influenza Virus: Which Definition?. J Med Microb Diagn 3:171. doi: 10.4172/2161-0703.1000171
Copyright: © 2014 Schuurmans MM. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Influenza virus infection poses a considerable risk for complications to the general population and in particular to solid organ transplant recipients (SOTR). Life-long immunosuppression in SOTR likely contributes to delayed clearance of influenza virus from the airways: Prolonged Viral Shedding (PVS) has important implications for potential infectivity and infection control measures. Duration of infectivity as measured by viral culture has been reported to last 4-6 days in the non-transplant setting. Shedding measured by Polymerase Chain Reaction (PCR) in immune competent patients is similar, 5-6 days. To date there is no recommended or widely accepted definition of PVS for influenza virus infections. The lack of a PVS definition makes comparisons between studies difficult. Most studies assess shedding duration by serial PCR of nasopharyngeal swabs. A number of studies calculate shedding from the time of onset of symptoms to the last positive detection. Shedding is considered to be “prolonged” if it continues on or beyond day 7 or 14. However, considerable variability exists in defining PVS. A large number of studies rely on two objective measures to define the duration of shedding: This requires at least two positive detections of viral material, usually by PCR. We discuss the different aspects of these definitions and propose a practical definition that takes into account a number of factors relevant to the topic.