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Understanding the influenza-like illness (ILI) incidence, circulation pattern of virus strains and spatiotemporal pattern of influenza transmission are important for designing control interventions. Based on the 10 years' surveillance data, we aimed to provide a baseline characterization and the epidemiology and dynamics of influenza virus in Shandong.We extracted surveillance and laboratory testing data. We estimated the ILI incidence and analyzed the predominant virus. A wavelet power analysis was used to illustrate the periodicity. In addition, we applied a linear regression model to characterize the correlation of influenza seasonality with longitude.The average ILI incidence was estimated to be 3744.79 per 1 million (95% confidence interval [CI]: 2558.09-4931.45) during 2009-2018. Influenza A/H1N1 and A/H3N2 strains predominated in the most influenza seasons in Shandong. The annual amplitude of influenza epidemics decreased with longitude (P 0.05). In contrast, the epidemic peak of influenza emerged earlier in the western region and increased with longitude in influenza A (P 0.05). The annual peak of the influenza B epidemic lagged a median of 4.2 weeks compared with that of influenza A.The development or modification of seasonal influenza vaccination strategies requires the recognition that the incidence is higher in preschool- and school-aged children. Although seasonal influenza circulates annually in Shandong, the predominant virus strain circulation pattern is extremely unpredictable and strengthening surveillance for the predominant virus strain is necessary. Lower longitude inland regions need to take nonpharmaceutical or pharmaceutical interventions in advance during influenza high-occurrence seasons.

Background Little comprehensive information on overall epidemic trend of notifiable respiratory infectious diseases is available in Shandong Province, China. This study aimed to determine the spatiotemporal distribution and epidemic characteristics of notifiable respiratory infectious diseases. Methods Time series was firstly performed to describe the temporal distribution feature of notifiable respiratory infectious diseases during 2005–2014 in Shandong Province. GIS Natural Breaks (Jenks) was applied to divide the average annual incidence of notifiable respiratory infectious diseases into five grades. Spatial empirical Bayesian smoothed risk maps and excess risk maps were further used to investigate spatial patterns of notifiable respiratory infectious diseases. Global and local Moran’s I statistics were used to measure the spatial autocorrelation. Spatial-temporal scanning was used to detect spatiotemporal clusters and identify high-risk locations. Results A total of 537,506 cases of notifiable respiratory infectious diseases were reported in Shandong Province during 2005–2014. The morbidity of notifiable respiratory infectious diseases had obvious seasonality with high morbidity in winter and spring. Local Moran’s I analysis showed that there were 5, 23, 24, 4, 20, 8, 14, 10 and 7 high-risk counties determined for influenza A (H1N1), measles, tuberculosis, meningococcal meningitis, pertussis, scarlet fever, influenza, mumps and rubella, respectively. The spatial-temporal clustering analysis determined that the most likely cluster of influenza A (H1N1), measles, tuberculosis, meningococcal meningitis, pertussis, scarlet fever, influenza, mumps and rubella included 74, 66, 58, 56, 22, 64, 2, 75 and 56 counties, and the time frame was November 2009, March 2008, January 2007, February 2005, July 2007, December 2011, November 2009, June 2012 and May 2005, respectively. Conclusions There were obvious spatiotemporal clusters of notifiable respiratory infectious diseases in Shandong during 2005–2014. More attention should be paid to the epidemiological and spatiotemporal characteristics of notifiable respiratory infectious diseases to establish new strategies for its control.

To identify circulating emerging/reemerging viral strains and epidemiological trends, an influenza sentinel surveillance network was established in Shandong Province, China, in 2005. Nasal and/or throat swabs from patients with influenza-like-illness were collected at sentinel hospitals. Influenza viruses were detected by reverse transcription polymerase chain reaction (RT-PCR) or virus isolation. From October 2005 to March 2012, 7763 (21.44 %) of 36,209 swab samples were positive for influenza viruses, including 5221 (67.25 %) influenza A and 2542 (32.75 %) influenza B. While the influenza viruses were detected year-round, their type/subtype distribution varied significantly. Peak influenza activity was observed from November to February. The proportion of laboratory-confirmed influenza cases was highest among participants aged 0-4 years (14.97 %) in the 2005-2009 and 2010-2012 influenza seasons and the positivity rate of influenza A(H1N1)pdm09 was highest in the 15 to 24 year age group during the 2009-2010 influenza season. Genetic analysis of hemagglutinin (HA) and neuraminidase (NA) genes revealed that the viruses matched seasonal influenza vaccine strains in general, with some amino acid mutations. Influenza A(H1N1)pdm09 strains isolated in Shandong Province were characterized by an S203T mutation that is specific to clade 7 isolates. This report illustrates that the Shandong Provincial influenza surveillance system was sensitive in detecting influenza virus variability by season and by genetic composition. This system will help official public health target interventions such as education programs and vaccines.

The purpose of this study was to understand the geographic extent, risk factors, and attack rate of the 2009 pandemic influenza A (H1N1) virus [A(H1N1)pdm09] infection in Shandong Province, China and to identify the influencing factors. A randomized serological survey of A(H1N1)pdm09 infection was carried out in August and September 2010. A total of 4,549 participants involved in the survey had their antibody levels tested by hemagglutination-inhibition assay. The overall seropositive rate for A(H1N1)pdm09 antibodies was 25.85%. The seropositive rate was 25.89% for the unvaccinated group, with statistically significant differences among individuals of different age groups, occupations, and cities. The highest seropositive rate was observed in young children aged 0-5 years and elderly people aged ≥60 years. Multivariate logistic regression revealed that subjects in rural areas had significantly higher odds ratio of A(H1N1)pdm09 seropositivity than those in the capital city. Individuals belonging to all professions, except for teachers, had significantly lower odds ratio of A(H1N1)pdm09 seropositivity compared with children in family care. Our data indicated that almost 26% of the residents in Shandong Province had appropriate antibody titers against A(H1N1)pdm09. This seroepidemiology study provides valuable data for understanding the epidemiology of the 2009 pandemic influenza and for planning future intervention strategies; moreover, it highlights the significance of seroprevelance studies.

Background The dominant viral etiologies responsible for acute respiratory infections (ARIs) are poorly understood, particularly among hospitalized patients. Improved etiological insight is needed to improve clinical management and prevention of ARIs. Methods Clinical and demographic information and throat swabs were collected from 607 patients from 2011 to 2013 in Shandong Province, China. Multiplex RT-PCR (SeeplexTM RV detection, Seegene) was performed to detected 12 respiratory viral pathogens. Results A total of 607 hospitalized patients were enrolled from 2011 to 2013. Viruses were identified in 35.75 % (217/607) of cases, including 78 influenza virus A and B (IVA and IVB), 47 para-influenza viruses (PIVs), 41 respiratory syncytial virus (RSV) and 38 adenovirus (ADV). For the children under 15 year old, the common detected viruses were influenza viruses, RSV, PIVS and ADV, while the principal respiratory viruses were human coronaviruses (HCoV), PIVs, influenza viruses for the old adults. Co-infections with multiple viruses were detected in 15.67 % of patients. Children under 5 years were more likely to have one or more detectable virus associated with their ARI. The peak of ARI caused by the respiratory viruses occurred in winter. Conclusion This study demonstrated respiratory viruses were the major cause of hospitalized ARI patients in Shandong Province, influenza virus was the most common detected, RSV was the highest incidence among the young children (≤5 years). These findings also gave a better understand of virus distribution among different age and seasons, which help to consider potential therapeutic approaches and develop effective prevention strategies for respiratory virus infection.

Background The first case of human infection with avian influenza A (H7N9) virus was identified in March, 2013 and the new H7N9 virus infected 134 patients and killed 45 people in China as of September 30, 2013. Family clusters with confirmed or suspected the new H7N9 virus infection were previously reported, but the family cluster of H7N9 virus infection in Shandong Province was first reported. Case presentation A 36-year-old man was admitted to Zaozhuang City Hospital with progressive respiratory distress and suspicion of impending acute respiratory distress syndrome on April 21. The chest radiography revealed bilateral ground-glass opacities and pulmonary lesions. The second case, the first case’s 4 year old son, was admitted to the same hospital on April 28 with fever and multiple patchy shadows in the bilateral lungs. Both of the two cases were confirmed to infect with H7N9 virus by the results of real-time reverse transcriptase-polymerase-chain reaction (rRT-PCR), virus isolation and serum antibody titer. At the same time, one environment samples was detected positive for H7N9 virus in the living poultry market in Zaozhuang. The homologous analysis of the full genome sequence indicated that both viruses from the patients were almost genetically identical. The field epidemiology investigation showed that the two cases had no recognized exposure to poultry, but had the exposure to the environment. The second case had substantial unprotected close exposure to his ill father and developed symptoms seven days after his last contact with his father. After surgery, the index case and his son were discharged on May 16 and May 6, respectively. 11 close contacts of both patients were identified and tested negative both the throat swabs and the serum antibody. Conclusion The infection of the index case probably resulted from contact with environmentally contaminated material. For the son, the probable infection source was from the index case during unprotected exposure, but the possibility from the environment or other sources could not be completely ruled out.