The frequency and seasonality of influenza and other respiratory viruses in T ennessee: two influenza seasons of surveillance data, 2010–2012

Background In 2010, the T ennessee D epartment of H ealth, in collaboration with the C enters for D isease C ontrol and P revention ( CDC ), expanded influenza surveillance in T ennessee to include other respiratory viruses. Objectives To determine the prevalence and seasonality of influenza and other respiratory viruses during the influenza seasons of 2010–2012. Methods Nasal and nasopharangeal swabs/washings from persons with influenza‐like illness were collected across Tennessee. Influenza and other respiratory viruses were identified using a molecular‐based respiratory virus panel. Influenza A positives were subtyped using real‐time PCR according to the CDC protocol. Data were analyzed to describe frequency and seasonality of circulating strains. Results Of the 933 positive specimens, 60·3% were identified as influenza viruses, 19·8% rhinovirus/enterovirus, 8·6% respiratory syncytial virus ( RSV ), 5·8% metapneumovirus, 3·0% adenovirus, and 2·5% parainfluenza viruses. In the 2010–2011 season, influenza B was prominent during weeks 48–3, while influenza A ( H 1 N 1) was most frequently identified during weeks 4–10. Influenza A ( H 3 N 2) was present at lower levels during weeks 48–17. However, in the 2011–2012 season, overall numbers of influenza cases were reduced and influenza A ( H 3 N 2) was the most abundant influenza strain. The expanded surveillance for other respiratory viruses noted an increase in identified specimens from the first to the second season for adenovirus, metapneumovirus, RSV , and rhinovirus/enterovirus. Conclusions This study provides data of the influenza strains in circulation in T ennessee. It also establishes a baseline and time of year to expect other respiratory viruses that will aid in detecting outbreaks of non‐influenza respiratory viruses in T ennessee.