[Evaluation of sentinel influenza surveillance of the last two seasons: 2013-2014 and 2014-2015]. / Sentinel influenza sürveyansinda son iki sezonun degerlendirilmesi: 2013-2014 ve 2014-2015.

Flu caused by influenza viruses, is a serious public health problem all over the world with its high morbidity and mortality. Therefore World Health Organization (WHO) regularly collects the results of national influenza surveillance, evaluates the results and shares them on international portal. Thus, it provides the possibility of rapid prevention and preparation of countries that needs to be taken on the fight against the epidemic flu. Starting from 2004-2005 season until today the current flu activity in our country is also followed in accordance with sentinel surveillance. The aim of this study was to evaluate the results of sentinel surveillance data obtained by National Influenza Reference Laboratory in Istanbul University Faculty of Medicine, in 2013-2014 and 2014-2015 seasons. For this purpose, nasal/nasopharyngeal swab samples taken from the patients diagnosed as influenza-like illness by the volunteer family physicians in Izmir, Istanbul, Antalya, Edirne and Bursa were included in the study. A total of 1240 samples were delivered to our laboratory in three days, in Virocult® transport culture medium according to cold chain rules. All the samples were studied by real-time polymerase chain reaction (Rt-PCR) according to the protocols of Centers for Disease Control and Prevention (CDC). In our study, the positivity rates of influenza viruses in 2013-2014 and 2014-2015 seasons were detected as 31.4% (202/641) and 44.4% (289/650), respectively. In 2013-2014 season, influenza A(H3N2) virus was the predominant type with a rate of 93.1% (188/202), and the rest was influenza B virus (14/202; 6.9%). In 2014-2015 season, influenza B virus has been dominated with a rate of 60.2% (174/289), and the rates of influenza A(H1N1)pdm09 and influenza A(H3N2) were 30.4% (88/289) and 9.3% (27/289), respectively. The flu season in 2013-2014 has started at 48th week and peaked at 52nd week, while it was started later in the second week in 2014-2015 season and peaked at 10th-13th week. The lineage of the influenza B viruses isolated in both seasons were identified as B/Yamagata. Antigenic characterization of influenza A viruses isolated in our laboratory was found compatible with the vaccine strains. In conclusion, surveillance studies are highly important for the determination of the effects of flu on public health and identification of the approaches for fighting with flu. In this sense, influenza surveillance of the countries are required to implement more effectively in an expanded field of scale.

[Influenza surveillance in nine consecutive seasons, 2003-2012: results from National Influenza Reference Laboratory, Istanbul Faculty Of Medicine, Turkey]. / 2003-2012 Yillarini Kapsayan Dokuz Sezonda Grip Sürveyansi Bulgulari: Istanbul Tip Fakültesi Ulusal Influenza Referans Laboratuvari Sonuçlari

Influenza is a public health problem that affects 5-20% of the world population annually causing high morbidity and mortality especially in risk groups. In addition to determining prevention and treatment strategies with vaccines and antivirals, surveillance data plays an important role in combat against influenza. Surveillance provides valuable data on characteristics of influenza activity, on types, sub-types, antigenic properties and antiviral resistance profile of circulating viruses in a given region. The first influenza surveillance was initiated as a pilot study in 2003 by now named National Influenza Reference Laboratory, Istanbul Faculty of Medicine. Surveillance was launched at national level by Ministry of Health in 2004 and two National Influenza Laboratories, one in Istanbul and the other in Ankara, have been conducting surveillance in Turkey. Surveillance data obtained for nine consecutive years, 2003-2012, by National Influenza Reference Laboratory in Istanbul Faculty of Medicine have been summarized in this report. During 2003-2012 influenza surveillance seasons, a total of 11.077 nasal swabs collected in viral transport medium were sent to the National Influenza Reference Laboratory, Istanbul for analysis. Immun-capture ELISA followed by MDCK cell culture was used for detection of influenza viruses before 2009 and real-time RT-PCR was used thereafter. Antigenic characterizations were done by hemagglutination inhibition assay with the reactives supplied by World Health Organization. Analysis of the results showed that influenza B viruses have entered the circulation in 2005-2006 seasons, and have contributed to the epidemics at increasing rates every year except in the 2009 pandemic season. Influenza B Victoria and Yamagata lineages were cocirculating for two seasons. For other seasons either lineage was in circulation. Antigenic characterization revealed that circulating B viruses matched the vaccine composition either partially or totally for only three seasons. Influenza A(H1N1) and A(H3N2) subtypes were in circulation since the beginning of the surveillance in 2003-2004 season either alone or in cocirculation. After the 2009 pandemic, A(H1N1) viruses were replaced by A(H1N1)pdm09. A(H1N1) and A(H1N1)pdm09 viruses matched the vaccine composition for all seasons. However, A(H3N2) viruses matched the vaccine composition in only three out of eight seasons. Analysis of the data revealed that, (a) influenza season has extended in Turkey and it lasts through May; (b) influenza peaks in different age groups depending on the season; (c) every year a different influenza type and subtype dominates the season; (d) influenza B has been circulating with increasing rate especially in the past six seasons. Influenza surveillance provides valuable data that can guide policy makers in developing programmes to prevent and reduce influenza burden. Therefore, addition of hospital based surveillance to general practice based sentinel surveillance will take influenza surveillance one step ahead in meeting the need for collecting data on severe influenza cases which will allow assessment of burden of influenza more reliably.