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Introduction/Objective. In August 2010, World Health Organization declared the beginning of the postpandemic phase of influenza surveillance. The aim of this study was to evaluate the epidemiological and virological characteristics of influenza and correlation between the influenza occurrence and weather conditions. Methods. We used surveillance reports of influenza and laboratory data from October 2010 to May 2015. Data for the analysis were collected through sentinel surveillance of influenza-like illness (ILI), severe acute respiratory illness (SARI), acute respiratory distress syndrome, and by virological surveillance. The nasal and throat swabs from all influenza cases were performed by the PCR laboratory method. Results. During the observed period, the highest rates of ILI were registered during the 2010/11 and 2012/13 seasons, with influenza A (H1N1)pdm09 and influenza B being predominant, respectively. The highest weekly age-specific rates of ILI were registered in school-age children (ages 5–14). Out of 1,466 samples collected, 720 (49.1%) were laboratory confirmed as influenza, and influenza A virus was more frequently detected than influenza B. Among confirmed cases of influenza, participation of patients with SARI or ILI was nearly equal (46% vs. 44.1%). There was a weak correlation observed between the decrease in temperature and rainfall and the increase in influenza detection (ρ = -0.04214 vs. ρ = -0.01545, respectively, p > 0.05). Conclusion. There is a need for continuous surveillance in order to predict seasonal trends and prepare for a timely response to influenza outbreak.

Introduction. Literature data concerning risk factors for severe influenza in post-2009 pandemic period, from low- and middle-income Central and Eastern European countries are very limited. Objective. The aim of this study was to investigate the risk factors for severe A(H1N1)pdm09 and A(H3N2) influenza during the post-2009 pandemic period. Methods. During four consecutive seasons of 2010/2011-2013/2014, nasopharyngeal or nasal and pharyngeal swab samples from 153 patients with mild and 147 patients with severe influenza were tested using real-time reverse transcription polymerase chain reaction (real-time RT PCR) assays. Results. The study indicated three statistically significant risk factors of influenza severity, including presence of chronic underlying illness/condition [odds ratio (OR) of 15.2, 95% confidence interval (CI) of 1.8-125.4, p = 0.001), age ≥15 years (OR 9.2, 95% CI 3.5-24.1, p < 0.001), and delay in medical care of more than two days after the symptoms onset (OR 3.2, 95% CI 1.6-6.4, p = 0.001). Conclusion. Obtained results confirmed that patients with chronic underlying illness/condition and older than 15 years had the highest risk for serious complications from influenza and highlighted the importance of start of antiviral therapy within the first two days of illness in order to reduce the risk for the most severe outcomes of influenza, such as acute respiratory distress syndrome and lethal outcome.

Introduction. At present, two phylogenetically distinct influenza B virus lineages, B/Yamagata and B/ Victoria, co-circulate worldwide and can cause significant morbidity and mortality. Objective. The aim of this study was to determine the prevalences of two influenza B virus lineages in the population of Vojvodina and to identify their antigenic and phylogenetic properties. Methods. A total of 369 and 334 nasopharyngeal, or nasal/throat swab samples, collected during the 2012/2013 and 2013/2014 seasons, respectively, were tested using specific singleplex influenza A, influenza B, influenza B/Yamagata and influenza B/Victoria real-time reverse transcription polymerase chain reaction (RT-PCR) assays. Antigenic and genetic testing were done by hemagglutination inhibition assay and hemagglutinin and neuraminidase gene sequence analysis, respectively. Results. During the 2012/2013 season, influenza B viruses were present in 53.4% (101/189) of influenza positive samples. The B/Yamagata-like viruses (81.2%) significantly predominated over the B/Victoria-like viruses (18.8%). Comparing to B/Victoria-like positive patients, among B/Yamagata-like positive patients, children 5-14 years of age were significantly more represented (5.3% vs. 35.4%, respectively), as well as patients with mild form of illness (15.8% vs. 45.1%, respectively). The results of sequence analysis and antigenic testing showed that tested viruses were not closely related to B/Wisconsin/1/2010, the vaccine virus for 2012/2013. During the 2013/2014 season influenza B viruses were not detected. Conclusion. The results of this study confirmed the health significance of influenza B viruses and indicated that B/Yamagata-like viruses were significantly more prevalent than B/Victoria lineage viruses, during the 2012/2013 season. They also showed a sub-optimal match between the tested viruses and the vaccine virus for season 2012/2013. [Projekat Ministarstva nauke Republike Srbije, br. TR31084]

Introduction. Human enteroviruses represent the most common etiological agents of aseptic meningitis. Rapid diagnosis of aseptic meningitis affects the management of patients. Objective. The aim of this work was to assess the efficacy of rapid antigen detection (RAD) assay for the confirmation of human enteroviruses in comparison to that of the conventional cell culture (CCC), and to identify the serotypes associated with aseptic meningitis cases in the Autonomous Province of Vojvodina. Methods. RAD assay was carried out using centrifugation of inoculated Vero, RD and HEp-2 cell cultures and indirect immunofluorescence with Pan-Enterovirus 2E11 reagent (Millipore-Chemicon). CCC was performed using the same type of cells and the same immunofluorescence reagent for enterovirus confirmation. Results. Out of 70 analyzed samples (29 cerebrospinal fluid specimens, 27 stool specimens, 9 rectal and 5 throat swabs) , 36 (51.4%) were positive by immunofluorescence after CCC and 34 (48.6%) by the RAD assay. The sensitivity of RAD assay was 94.4% and specificity 100%. Detection time of enteroviruses by the RAD assay was 3 days, and by CCC varied from 3 to 13 days (mean time 6.1 days). Within 72 h from inoculation, a cytopathic effect (CPE) occurred in only 19 (47.5%) of 40 CPE positive samples. Serotyping revealed 11 types of enteroviruses: coxsackievirus A16, B3, B4, B5, and echovirus 2, 4, 6, 11, 13, 16 and 30. Conclusion. The RAD assay was slightly less sensitive than CCC and significantly shortened the detection time of enteroviruses, so it may be useful in rapid diagnosis of enteroviral meningitis.