Evaluation of the Activity of Influenza and Influenza-Like Viruses in the Epidemic Season 2013/2014.

Infections caused by respiratory viruses can have different clinical symptoms, while specific set of symptoms can be induced by different viruses. Despite usually mild course of disease, some viruses causing certain disease entity can result in serious complications. Therefore, quick and appropriate diagnostic is crucial for administering proper treatment. In the epidemic season 2013/2014, 2,497 specimens were tested. Infections caused by influenza viruses were confirmed in 9.8%, while infections caused by influenza-like viruses (ILI) in 13.2%. The co-domination of A/H1N1/pdm09 (29.4%) with A/H3N2/ (30.6%) was observed among circulating subtypes of influenza virus type A. Analysis of positive specimens categorized into 7 age groups indicated that most of morbidity to influenza was noted in the age intervals: 26-44 (22.9%) and 45-64 years old (21.6%). Considering infections caused by influenza-like viruses, the highest amount of positive cases was registered in the age group 0-4 years old (92.7%) with the highest ratio of RSV (87.9%) and PIV-3 (10.5%). Judging by the epidemiological and virological indicators, the 2013/14 influenza season was mild and only low virus activity was reported in Poland as well as in most European countries. Still, 9,000 hospitalizations and 17 deaths were registered in Poland during this epidemic season.