Epidemiological features and time-series analysis of influenza incidence in urban and rural areas of Shenyang, China, 2010-2018.

In recent years, there have been a significant influenza activity and emerging influenza strains in China, resulting in an increasing number of influenza virus infections and leading to public health concerns. The aims of this study were to identify the epidemiological and aetiological characteristics of influenza and establish seasonal autoregressive integrated moving average (SARIMA) models for forecasting the percentage of visits for influenza-like illness (ILI%) in urban and rural areas of Shenyang. Influenza surveillance data were obtained for ILI cases and influenza virus positivity from 18 sentinel hospitals. The SARIMA models were constructed to predict ILI% for January-December 2019. During 2010-2018, the influenza activity was higher in urban than in rural areas. The age distribution of ILI cases showed the highest rate in young children aged 0-4 years. Seasonal A/H3N2, influenza B virus and pandemic A/H1N1 continuously co-circulated in winter and spring seasons. In addition, the SARIMA (0, 1, 0) (0, 1, 2)12 model for the urban area and the SARIMA (1, 1, 1) (1, 1, 0)12 model for the rural area were appropriate for predicting influenza incidence. Our findings suggested that there were regional and seasonal distinctions of ILI activity in Shenyang. A co-epidemic pattern of influenza strains was evident in terms of seasonal influenza activity. Young children were more susceptible to influenza virus infection than adults. These results provide a reference for future influenza prevention and control strategies in the study area.

Epidemiological study of scarlet fever in Shenyang, China.

BACKGROUND: Since 2011, there has been an increase in the incidence of scarlet fever across China. The main objective of this study was to depict the spatiotemporal epidemiological characteristics of the incidence of scarlet fever in Shenyang, China, in 2018 so as to provide the scientific basis for effective strategies of scarlet control and prevention. METHODS: Excel 2010 was used to demonstrate the temporal distribution at the month level and ArcGIS10.3 was used to demonstrate the spatial distribution at the district/county level. Moran's autocorrelation coefficient was used to examine the spatial autocorrelation and the Getis-Ord statistic was used to determine the hot-spot areas of scarlet fever. RESULTS: A total of 2314 scarlet fever cases were reported in Shenyang in 2018 with an annual incidence of 31.24 per 100,000. The incidence among males was higher than that among females(p<0.001). A vast majority of the cases (96.89%) were among children aged 3 to 11 years. The highest incidence was 625.34/100,000 in children aged 5-9 years. In 2018 there were two seasonal peaks of scarlet fever in June (summer-peak) and December (winter-peak). The incidence of scarlet fever in urban areas was significantly higher than that in rural areas(p<0.001). The incidence of scarlet fever was randomly distributed in Shenyang. There are hotspot areas located in seven districts. CONCLUSIONS: Urban areas are the hot spots of scarlet fever and joint prevention and control measures between districts should be applied. Children aged 3-11 are the main source of scarlet fever and therefore the introduction of prevention and control into kindergarten and primary schools may be key to the control of scarlet fever epidemics.

Analysis of BDS Fractional Cycle Biases and PPP Ambiguity Resolution.

It is difficult to enable traditional precise point positioning (PPP) with ambiguity resolution (AR) due to fractional cycle biases (FCBs), which limit the accuracy and reliability of positioning results. The BeiDou Navigation Satellite System (BDS) has been providing continuous positioning, navigation, and timing (PNT) services in the global region since the end of 2018. The BDS constellation includes geostationary earth orbit (GEO), inclined geostationary orbit (IGSO), and medium earth orbit (MEO) satellites. However, its hybrid constellation structure and the satellite-side multipath effect have hindered the BDS PPP AR for two main reasons: (1) some receivers have half-cycle biases between GEO and non-GEO satellites, which result in the inconsistency of hardware delays for each satellite type; (2) the correction model for elevation-dependent satellite-side multipath effect is only applicable to IGSO and MEO, while in the case of GEO the effect cannot be effectively weakened or eliminated. To rectify these problems, a suitable strategy is proposed for estimating BDS FCBs, whereby the GEO FCBs and non-GEO FCBs are estimated independently. Results show that the FCBs estimated by the new strategy for GEO and non-GEO are more stable compared to the traditional strategy. The GEO wide-lane (WL) FCBs fluctuate less than 0.3 cycle in one month, except for C05, while the variation of non-GEO WL FCBs is about 0.1 cycle. In addition, compared to the traditional strategy, the fractions of GEO WL ambiguities after the removal of FCBs estimated by the new strategy can be improved noticeably from 53.5% to 78.5%, and from 71.8% to 92.3% for <0.15 cycle and <0.25 cycle respectively, which could be comparable with non-GEO. Simultaneously, the improvement of GEO narrow-lane (NL) ambiguities is from 28.9% to 40.2%, and from 40.4% to 53.3% for <0.10 cycle and <0.15 cycle respectively, are less noticeable. This is mainly due to the low precision IGS products for GEO. After PPP AR, the mean convergence time is shorted from 56.0 min to 43.6 min, and from 71.6 min to 62.7 min for static PPP and kinematic PPP, respectively.

Performance Analysis of BDS Medium-Long Baseline RTK Positioning Using an Empirical Troposphere Model.

For GPS medium-long baseline real-time kinematic (RTK) positioning, the troposphere parameter is introduced along with coordinates, and the model is ill-conditioned due to its strong correlation with the height parameter. For BeiDou Navigation Satellite System (BDS), additional difficulties occur due to its special satellite constellation. In fact, relative zenith troposphere delay (RZTD) derived from high-precision empirical zenith troposphere models can be introduced. Thus, the model strength can be improved, which is also called the RZTD-constrained RTK model. In this contribution, we first analyze the factors affecting the precision of BDS medium-long baseline RTK; thereafter, 15 baselines ranging from 38 km to 167 km in different troposphere conditions are processed to assess the performance of RZTD-constrained RTK. Results show that the troposphere parameter is difficult to distinguish from the height component, even with long time filtering for BDS-only RTK. Due to the lack of variation in geometry for the BDS geostationary Earth orbit satellite, the long convergence time of ambiguity parameters may reduce the height precision of GPS/BDS-combined RTK in the initial period. When the RZTD-constrained model was used in BDS and GPS/BDS-combined situations compared with the traditional RTK, the standard deviation of the height component for the fixed solution was reduced by 52.4% and 34.0%, respectively.

Early use of glucocorticoids was a risk factor for critical disease and death from pH1N1 infection.

BACKGROUND: Glucocorticoids increase the risk of developing critical disease from viral infections. However, primary care practitioners in China use them as antipyretics, potentially exposing hundreds of millions to this risk. METHODS: We enrolled all patients with confirmed pandemic influenza A (pH1N1) virus infection aged ≥3 years with available medical records at 4 Shenyang City hospitals from 20 October to 30 November 2009. A critical patient was any confirmed, hospitalized pH1N1 patient who developed ≥1 of the following: death, respiratory failure, septic shock, failure or insufficiency of ≥2 nonpulmonary organs, mechanical ventilation, or ICU admission. In a retrospective cohort study, we evaluated the risk of developing critical illness in relation to early (≤72 hours of influenza-like illness [ILI] onset) glucocorticoids treatment. RESULTS: Of the 83 hospitalized case-patients, 46% developed critical illness, 17% died, and 37% recovered and were discharged. Critically ill and other patients did not differ by underlying conditions and severity, median temperature at first clinic visit, and other measured risk factors. Of 17 patients who received early glucocorticoid treatment, 71% subsequently developed critical disease compared with 39% of 66 patients who received late (>72 hours) or no glucocorticoid treatment (RR(M-H) = 1.8, 95% CI = 1.2-2.8, after adjusting for 2 summary variables; ie, presence of underlying diseases and presence of underlying risk factors). Proportional hazards modeling showed that use of glucocorticoids tripled the hazard of developing critical disease (hazard ratio [HR] = 2.9, 95% CI = 1.3-6.2, after adjusting for the same summary variables). CONCLUSIONS: Early use of parenteral glucocorticoids therapy for fever reduction and pneumonia prevention increases the risk for critical disease or death from pH1N1 infection. We recommend that guidelines on glucocorticoid use be established and enforced.

[An outbreak of human Streptococcus suis serotype 2 infections presenting with toxic shock syndrome in Sichuan, China].

OBJECTIVE: In mid-July 2005, five patients presented with septic shock to a hospital in Ziyang city in Sichuan, China, to identify the etiology of the unknown reason disease, an epidemiological, clinical, and laboratory study were conducted. METHODS: An enhanced surveillance program were established in Sichuan, the following activities were introduced: active case finding in Sichuan of (a) laboratory diagnosed Streptococcus suis infection and (b) clinically diagnosed probable cases with exposure history; supplemented by (c) monitoring reports on meningococcal meningitis. Streptococcus suis serotype 2 infection was confirmed by culture and biochemical reactions, followed by sequencing for specific genes for serotype and virulence factors. RESULTS: From June 10 to August 21, 2005, 68 laboratory confirmed cases of human Streptococcus suis infections were reported. All were villagers who gave a history of direct exposure to deceased or sick pigs in their backyards where slaughtering was performed. Twenty six (38%) presented with toxic shock syndrome of which 15 (58%) died. Other presentations were septicaemia or meningitis. All isolates were tested positive for genes for tuf, species-specific 16S rRNA, cps2J, mrp, ef and sly. There were 136 clinically diagnosed probable cases with similar exposure history but incomplete laboratory investigations. CONCLUSION: An outbreak of human Streptococcus suis serotype 2 infections occurred in villagers after direct exposure to deceased or sick pigs in Sichuan. Prohibition of slaughtering in backyards brought the outbreak to a halt. A virulent strain of the bacteria is speculated to be in circulation, and is responsible for the unusual presentation of toxic shock syndrome with high case fatality.

[Anlysis on features of dead cases with human Streptococcus suis infections].

OBJECTIVE: To describe the clinical and epidemiological features of dead cases with human Streptococcus suis infections, and to find the target population for preventing death and the related indicators. METHODS: Epidemiological investigation on human Streptococcus suis infections was implemented used unified questionnaires. Analysis on dead cases and survival cases (as contrast) was done. RESULTS: The population with highest fatality rate was in 40-49 age group. 97.37% of dead cases had toxic shock syndrome. The mean interval from onset to admission was 0.76 days, and the mean course was 2.11 days. The progression among dead cases was faster than that among survival cases. Chief clinical manifestations of dead cases that are more frequent than survival cases are purpura (73.68%), diarrhea (50.0%), dyspnea (21.05%), conjunctival congestion (34.21%), etc. Renal impairment and liver involvement in dead cases were more significant than that in survival cases. No significant difference between mean incubation period, exposure rates of main risk factors in dead cases and in survival cases was found. CONCLUSION: Preventing toxic shock syndrome might reduce the fatality rate. The target population for preventing death is aged > or = 40. Liver function and renal function testing might be indicators for monitoring the progression of human Streptococcus suis infections.

[Matched case-control study for risk factors of human Streptococcus suis infection in Sichuan Province, China].

OBJECTIVE: To study the potential risk factors of human infecting with Streptococcus suis. METHODS: 1: M matched case-control study was conducted. 29 human cases of Streptococcus suis infection in the early phase were included in the case group, Patients' family members, neighbors and peoples who had worked together with patients to handle deceased or sick pigs in the last week were recruited as matched controls. There were 147 controls in total. Both cases and controls received questionnaire investigation including the ways to contact sick/dead pigs. Conditional logistic regression was employed to analyze matching data. RESULTS: According to the results of multivariate analysis, slaughtering (OR = 11.978, 95% CI: 3.355-42.756), carcasses cutting and processing (OR = 3.008, 95% CI: 1.022-8.849) sick/dead pigs were associated with cases related to human Streptococcus suis infection. The attributable risk proportion were 91.65% and 66.76% respectively. The other types of exposures to sick/ dead pigs, including feeding, selling, burying and eating, were not associated with the human Streptococcus suis infection in our study population. CONCLUSION: Slaughtering, carcasses cutting and processing sick/dead pigs were important risky behavior for humans to be infected by Streptococcus suis.