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The frequency and seasonality of influenza and other respiratory viruses in Tennessee: two influenza seasons of surveillance data, 2010-2012.

ABSTRACT: In 2010, the Tennessee Department of Health, in collaboration with the Centers for Disease Control and Prevention (CDC), expanded influenza surveillance in Tennessee to include other respiratory viruses.To determine the prevalence and seasonality of influenza and other respiratory viruses during the influenza seasons of 2010-2012.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.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(H1N1) was most frequently identified during weeks 4-10. Influenza A(H3N2) 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 (H3N2) 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.This study provides data of the influenza strains in circulation in Tennessee. 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 Tennessee.

SUBMITTER: Landes MB

PROVIDER: S-EPMC4634273 | biostudies-other | 2013 Nov

REPOSITORIES: biostudies-other

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Project description:The seasonality of influenza and respiratory syncytial virus (RSV) is well known, and many analyses have been conducted in temperate countries; however, this is still not well understood in tropical countries. Previous studies suggest that climate factors are involved in the seasonality of these viruses. However, the extent of the effect of each climate variable is yet to be defined.We investigated the pattern of seasonality and the effect of climate variables on influenza and RSV at three sites of different latitudes: the Eastern Visayas region and Baguio City in the Philippines, and Okinawa Prefecture in Japan. Wavelet analysis and the dynamic linear regression model were applied. Climate variables used in the analysis included mean temperature, relative and specific humidity, precipitation, and number of rainy days. The Akaike Information Criterion estimated in each model was used to test the improvement of fit in comparison with the baseline model.At all three study sites, annual seasonal peaks were observed in influenza A and RSV; peaks were unclear for influenza B. Ranges of climate variables at the two Philippine sites were narrower and mean variables were significantly different among the three sites. Whereas all climate variables except the number of rainy days improved model fit to the local trend model, their contributions were modest. Mean temperature and specific humidity were positively associated with influenza and RSV at the Philippine sites and negatively associated with influenza A in Okinawa. Precipitation also improved model fit for influenza and RSV at both Philippine sites, except for the influenza A model in the Eastern Visayas.Annual seasonal peaks were observed for influenza A and RSV but were less clear for influenza B at all three study sites. Including additional data from subsequent more years would help to ascertain these findings. Annual amplitude and variation in climate variables are more important than their absolute values for determining their effect on the seasonality of influenza and RSV.

Project description:National surveillance of avian influenza virus (AIV) in South Korea has been annually conducted for the early detection of AIV and responses to the introduction of highly pathogenic avian influenza (HPAI) virus. In this study, we report on a nationwide surveillance study of AIV in domestic poultry and wild birds in South Korea between 2012 and 2014.During the surveillance programs between 2012 and 2014, 141,560 samples were collected. Of these, 102,199 were from poultry farms, 8215 were from LBMs, and 31,146 were from wild bird habitats. The virus isolation was performed by inoculation of embryonated chicken eggs and AIV isolates were detected using hemagglutination assay. For subtying of AIV, the hemagglutinin and neuraminidase genes were confirmed by sequencing. Phylogenetic analysis of the H5 subtypes was performed using 28 H5 AIV isolates.Between 2012 and 2014, a total of 819 AIV were isolated from 141,560 samples. Virus isolation rates for AIV were 0.6, 0.4, 0.1, and 2.7% in wild birds (n?=?202), domestic ducks (n?=?387), minor poultry (n?=?11), and the live bird market (LBM) (n?=?219), respectively. In wild birds, various subtypes were found including H1-H7 and H9-H13. The major subtypes were H5 (n?=?48, 23.9%: N3 (n?=?4) and N8 (n?=?44)), H4 (n?=?39, 19.4%), and H1 (n?=?29, 14.4%). In domestic poultry, mainly ducks, the H5N8 (n?=?275, 59.3%), H3 (n?=?30, 17.2%), and H6 (n?=?53, 11.4%) subtypes were predominantly found. The most frequently detected subtypes in LBM, primarily Korean native chicken, were H9 (n?=?169, 77.2%). H3 (n?=?10, 4%) and H6 (n?=?30, 13.7%) were also isolated in LBM. Overall, the prevalence of AIV was found to be higher between winter and spring and in western parts of South Korea. The unusual high prevalence of the H5 subtype of AIV was due to the large scale outbreak of H5N8 HPAI in wild birds and domestic poultry in 2014.Enhanced surveillance and application of effective control measures in wild birds and domestic poultry, including LBM, should be implemented to control AI and eradicate HPAI.

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The frequency and seasonality of influenza and other respiratory viruses in Tennessee: two influenza seasons of surveillance data, 2010-2012.

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