Effects of School Holidays on Seasonal Influenza in South Korea, 2014-2016.
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ABSTRACT:
SUBMITTER: Ryu S
PROVIDER: S-EPMC7399705 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description: Not available
| S-EPMC4036756 | biostudies-literature
Project description:During 2014-2016, clade 2.3.4.4 H5N8 high pathogenicity avian influenza virus (HPAIV) caused the largest known avian influenza epidemic in South Korea. Based on data from earlier H5N8 outbreaks, primitive H5N8 virus in South Korea was classified into five subgroups: C1, C2, C3, C4, and C5. The present study investigated the pathogenic and molecular epidemiologic characteristics of H5N8 viruses obtained from 388 cases of poultry farms and 85 cases of wild bird infections in South Korea during 2014-2016. Representative viruses of subgroups C1, C2, and C4 showed significant pathobiological differences in specific pathogen-free (SPF) chickens, with the H1731 (C1) virus showing substantially lower infectivity, transmissibility, and pathogenicity than the H2102 (C2) and H1924 (C4) viruses. Full genome sequence analysis showed the number of mutations that significantly increased in domestic duck-origin H5N8 HPAIVs compared to the viruses from gallinaceous poultry. These differences may have been due to the long-term circulation of viruses in domestic duck farms. The same mutations, at positions 219 and 757 of PB1, independently evolving in the C0, C1, and C2 subgroups may have been positively selected, resulting in convergent evolution at the amino acid level. Bayesian discrete trait phylodynamic analysis (DTA) indicated multiple introductions of H5N8 HPAIV from wild birds into domestic poultry in various regions in South Korea. Following initial viral introduction into domestic duck farms in the western part of Korea, domestic ducks played a major role in viral transmission and maintenance. These findings highlight the need for continued genomic surveillance and pathobiological characterization of HPAIV in birds. Enhanced biosecurity in poultry farms should be implemented to prevent the introduction, maintenance, and spread of HPAIV.
| S-EPMC9253604 | biostudies-literature
Project description:BackgroundThis study was performed to investigate the disease burden of seasonal influenza in adults ?20 years of age in Korea, based on surveillance data from the Hospital-based Influenza Morbidity & Mortality Surveillance (HIMM) network.Materials and methodsThe HIMM network is composed of two surveillance systems: emergency room-based and inpatients-based surveillance. A total of ten university hospitals all over the country are included in the surveillance network. The adult catchment population of the HIMM network was calculated by using the data of each hospital and the database of the Health Insurance Review and Assessment Service (HIRA) of Korea. The incidence rates of laboratory-confirmed medically-attended influenza, laboratory-confirmed influenza-related admission and laboratory-confirmed influenza-related death were calculated based on the catchment population. The socioeconomic burden of influenza was estimated using the human capital approach.ResultsDuring the 2013-2014 influenza season, the calculated adult catchment population of the HIMM network was 1,380,000. The incidence of medically-attended laboratory-confirmed influenza infection was 242.8 per 100,000 adults. The incidence of laboratory-confirmed influenza-related admission was 57.9 per 100,000 adults. The incidence of laboratory-confirmed influenza-related death was 3.1 per 100,000 adults. The total socioeconomic cost of 2013-2014 seasonal influenza in Korean adult population was estimated as 125 million USD (1 USD = 1,100 KRW).ConclusionThe disease burden of 2013-2014 seasonal influenza in Korean adult population is very high and indicates that more active prevention and control policies will be needed to decrease the burden. Additional researches will be needed to assess the burden of seasonal influenza in the Korean child population.
| S-EPMC5344334 | biostudies-literature
Project description: Not available
| S-EPMC4178401 | biostudies-literature
Project description:BackgroundNational 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.MethodsDuring 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.ResultsBetween 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.ConclusionsEnhanced surveillance and application of effective control measures in wild birds and domestic poultry, including LBM, should be implemented to control AI and eradicate HPAI.
| S-EPMC5351195 | biostudies-literature
Project description:IntroductionWe investigated an outbreak of influenza-like illness (ILI) at a boarding school in Eastern Cape Province, South Africa. We aimed to confirm the etiological agent, estimate attack rates and identify risk factors for illness.MethodsWe conducted a retrospective cohort study including senior school boarders (n=308). Students with ILI (cough and fever) were identified through school medical records. We also conducted a questionnaire-based cross-sectional study among senior students including boarders (n=107) and day students (n=45). We collected respiratory specimens for respiratory pathogen testing by real-time polymerase chain reaction from a subset of symptomatic students. We calculated attack rates of medically attended ILI (medILI) and identified factors associated with medILI using logistic regression. We calculated seasonal influenza vaccine effectiveness (VE) against medILI.ResultsInfluenza A (H3N2) virus was detected in 61% (23/38) of specimens. Attack rate for medILI was 13% among boarders (39/308) in the cohort study and 20% in both day students (9/45) and boarders (21/107) in the cross-sectional study. Playing squash was associated with medILI (aOR 5.35, 95% confidence interval [95% CI]: 1.68-17.07). Of the boarders, 19% (57/308) were vaccinated before the outbreak. The adjusted VE against medILI was 18% (aOR 0.82, 95% CI 0.38-1.78). The outbreak led to cancellation of several events and the need for academic remedial sessions.ConclusionWe confirmed an influenza A (H3N2) virus outbreak with a high attack rate. The outbreak affected academic and sports activities. Participation in sports and social gatherings while experiencing ILI should be discouraged to reduce viral transmission and impact on school activities.
| S-EPMC6658148 | biostudies-literature
Project description:Porcine deltacoronavirus (PDCoV) is a newly emerged enterotropic swine coronavirus that causes enteritis and diarrhoea in piglets. Here, a nested reverse transcription (RT)-PCR approach for the detection of PDCoV was developed to identify and characterize aetiologic agent(s) associated with diarrhoeal diseases in piglets in South Korea. A PCR-based method was applied to investigate the presence of PDCoV in 683 diarrhoeic samples collected from 449 commercial pig farms in South Korea from January 2014 to December 2016. The molecular-based survey indicated a relatively high prevalence of PDCoV (19.03%) in South Korea. Among those, the monoinfection of PDCoV (9.66%) and co-infection of PDCoV (6.30%) with porcine epidemic diarrhoea (PEDV) were predominant in diarrhoeal samples. The full-length genomes or the complete spike genes of the most recent strains identified in 2016 (KNU16-07, KNU16-08 and KNU16-11) were sequenced and analysed to characterize PDCoV currently prevalent in South Korea. We found a single insertion-deletion signature and dozens of genetic changes in the spike (S) genes of the KNU16 isolates. Phylogenetic analysis based on the entire genome and spike protein sequences of these strains indicated that they are most closely related to other Korean isolates grouped with the US strains. However, Korean PDCoV strains formed different branches within the same cluster, implying continuous evolution in the field. Our data will advance the understanding of the molecular epidemiology and evolutionary characteristics of PDCoV circulating in South Korea.
| S-EPMC7169712 | biostudies-literature
Project description:An outbreak of febrile respiratory illness associated with human adenovirus (HAdV) occurred in the South Korea military during the 2014-15 influenza season and thereafter. Molecular typing and phylogenetic analysis of patient samples identified HAdV type 55 as the causative agent. Emergence of this novel HAdV necessitates continued surveillance in military and civilian populations.
| S-EPMC5443441 | biostudies-literature
Project description:During 2014–2016 HPAI outbreak in South Korea, H5N8 viruses have been mostly isolated in western areas of the country, which provide wintering habitats for wild birds and have a high density of poultry. Analysis of a total of 101 Korean isolates revealed that primitive H5N8 viruses (C0 group) have evolved into multiple genetic subgroups appearing from various epidemiological sources, namely, the viruses circulating in poultry farms (C1 and C5) and those reintroduced by migratory birds in late 2014 (C2 and C4). No C3 groups were detected. The results may explain the possible reasons of the recent long-term persistence of H5N8 viruses in South Korea, and help to develop the effective measures in controlling HPAI viruses.
| S-EPMC5366307 | biostudies-literature
Project description:School closure is often considered as an influenza control measure, but its effects on transmission are poorly understood. We used 2 approaches to estimate how school holidays affect the contact parameter (the per capita rate of contact sufficient for infection transmission) for influenza using primary care data from England and Wales (1967-2000). Firstly, we fitted an age-structured susceptible-infectious-recovered model to each year's data to estimate the proportional change in the contact parameter during school holidays as compared with termtime. Secondly, we calculated the percentage difference in the contact parameter between holidays and termtime from weekly values of the contact parameter, estimated directly from simple mass-action models. Estimates were combined using random-effects meta-analysis, where appropriate. From fitting to the data, the difference in the contact parameter among children aged 5-14 years during holidays as compared with termtime ranged from a 36% reduction to a 17% increase; estimates were too heterogeneous for meta-analysis. Based on the simple mass-action model, the contact parameter was 17% (95% confidence interval: 10, 25) lower during holidays than during termtime. Results were robust to the assumed proportions of infections that were reported and individuals who were susceptible when the influenza season started. We conclude that school closure may reduce transmission during influenza outbreaks.
| S-EPMC5860259 | biostudies-literature