ObjectiveAnalyzing the epidemiological characteristics of influenza cases among children aged 0–17 years in Guangzhou from 2019 to 2022. Assessing the relationships between multiple meteorological factors and influenza, improving the early warning systems for influenza, and providing a scientific basis for influenza prevention and control measures.MethodsThe influenza data were obtained from the Chinese Center for Disease Control and Prevention. Meteorological data were provided by Guangdong Meteorological Service. Spearman correlation analysis was conducted to examine the relevance between meteorological factors and the number of influenza cases. Distributed lag non-linear models (DLNM) were used to explore the effects of meteorological factors on influenza incidence.ResultsThe relationship between mean temperature, rainfall, sunshine hours, and influenza cases presented a wavy pattern. The correlation between relative humidity and influenza cases was illustrated by a U-shaped curve. When the temperature dropped below 13°C, Relative risk (RR) increased sharply with decreasing temperature, peaking at 5.7°C with an RR of 83.78 (95% CI: 25.52, 275.09). The RR was increased when the relative humidity was below 66% or above 79%, and the highest RR was 7.50 (95% CI: 22.92, 19.25) at 99%. The RR was increased exponentially when the rainfall exceeded 1,625 mm, reaching a maximum value of 2566.29 (95% CI: 21.85, 3558574.07) at the highest rainfall levels. Both low and high sunshine hours were associated with reduced incidence of influenza, and the lowest RR was 0.20 (95% CI: 20.08, 0.49) at 9.4 h. No significant difference of the meteorological factors on influenza was observed between males and females. The impacts of cumulative extreme low temperature and low relative humidity on influenza among children aged 0–3 presented protective effects and the 0–3 years group had the lowest RRs of cumulative extreme high relative humidity and rainfall. The highest RRs of cumulative extreme effect of all meteorological factors (expect sunshine hours) were observed in the 7–12 years group.ConclusionTemperature, relative humidity, rainfall, and sunshine hours can be used as important predictors of influenza in children to improve the early warning system of influenza. Extreme weather reduces the risk of influenza in the age group of 0–3 years, but significantly increases the risk for those aged 7–12 years.

BACKGROUND:Influenza imposes a heavy burden on public health. Little is known, however, of the associations between detailed measures of exposure to ambient air pollution and influenza at an individual level. OBJECTIVE:We examined individual-level associations between six criteria air pollutants and influenza using case-crossover design. METHODS:In this individual-level time-stratified case-crossover study, we linked influenza cases collected by the Guangzhou Center for Disease Control and Prevention from 1 January 2013 to 31 December 2019 with individual residence-level exposure to particulate matter (PM2.5 and PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and carbon monoxide (CO). The exposures were estimated for the day of onset of influenza symptoms (lag 0), 1-7 d before the onset (lags 1-7), as well as an 8-d moving average (lag07), using a random forest model and linked to study participants' home addresses. Conditional logistic regression was developed to investigate the associations between short-term exposure to air pollution and influenza, adjusting for mean temperature, relative humidity, public holidays, population mobility, and community influenza susceptibility. RESULTS:N=108,479 eligible cases were identified in our study. Every 10-μg/m3 increase in exposure to PM2.5, PM10, NO2, and CO and every 5-μg/m3 increase in SO2 over 8-d moving average (lag07) was associated with higher risk of influenza with a relative risk (RR) of 1.028 (95% CI: 1.018, 1.038), 1.041 (95% CI: 1.032, 1.049), 1.169 (95% CI: 1.151, 1.188), 1.004 (95% CI: 1.003, 1.006), and 1.134 (95% CI: 1.107, 1.163), respectively. There was a negative association between O3 and influenza with a RR of 0.878 (95% CI: 0.866, 0.890). CONCLUSIONS:Our findings suggest that short-term exposure to air pollution, except for O3, is associated with greater risk for influenza. Further studies are necessary to decipher underlying mechanisms and design preventive interventions and policies. https://doi.org/10.1289/EHP12145.

Background: Climatic variables constitute important extrinsic determinants of transmission and seasonality of influenza. Yet quantitative evidence of independent associations of viral transmissibility with climatic factors has thus far been scarce and little is known about the potential effects of interactions between climatic factors on transmission. Objective: This study aimed to examine the associations of key climatic factors with risk of influenza transmission in subtropical Guangzhou. Methods: Influenza epidemics were identified over a 17-year period using the moving epidemic method (MEM) from a dataset of N = 295,981 clinically- and laboratory-confirmed cases of influenza in Guangzhou. Data on eight key climatic variables were collected from China Meteorological Data Service Centre. Generalized additive model combined with the distributed lag non-linear model (DLNM) were developed to estimate the exposure-lagresponse curve showing the trajectory of instantaneous reproduction number (Rt) across the distribution of each climatic variable after adjusting for depletion of susceptible, inter-epidemic effect and school holidays. The potential interaction effects of temperature, humidity and rainfall on influenza transmission were also examined. Results: Over the study period (2005-21), 21 distinct influenza epidemics with varying peak timings and durations were identified. Increasing air temperature, sunshine, absolute and relative humidity were significantly associated with lower Rt, while the associations were opposite in the case of ambient pressure, wind speed and rainfall. Rainfall, relative humidity, and ambient temperature were the top three climatic contributors to variance in transmissibility. Interaction models found that the detrimental association between high relative humidity and transmissibility was more pronounced at high temperature and rainfall. Conclusion: Our findings are likely to help understand the complex role of climatic factors in influenza transmission, guiding informed climate-related mitigation and adaptation policies to reduce transmission in high density subtropical cities.

BACKGROUND: Influenza imposesaheavyburdenonpublichealth. Littleisknown, however, oftheassociationsbetweendetailedmeasuresofexposure toambientairpollutionandinfluenza atanindividuallevel. OBJECTIVE: We examinedindividual-levelassociationsbetweensixcriteriaairpollutantsandinfluenza usingcase-crossoverdesign. METHODS: In thisindividual-leveltime-stratified case-crossoverstudy, welinkedinfluenza casescollectedbytheGuangzhouCenterforDisease Control andPreventionfrom1January2013to31December2019withindividualresidence-levelexposuretoparticulatematter(PM2: 5 and PM10), sulfur dioxide(SO2), nitrogendioxide(NO2), ozone(O-3) andcarbonmonoxide(CO). Theexposureswereestimatedforthedayofonsetofinfluenza symptoms (lag0), 1-7 dbeforetheonset(lags1-7), aswellasan8-dmovingaverage(lag07), usingarandomforestmodelandlinkedtostudyparticipants' home addresses. Conditionallogisticregressionwasdevelopedtoinvestigatetheassociationsbetweenshort-termexposuretoairpollution and influenza, adjustingformeantemperature, relativehumidity, publicholidays, populationmobility, andcommunityinfluenza susceptibility. RESULTS: N = 108,479eligiblecaseswereidentified inourstudy. Every10-mu g/m(3) increase inexposuretoPM(2:5), PM10, NO (2), andCOandevery 5-mu g/m(3) increase inSO(2) over 8-dmovingaverage(lag07) wasassociatedwithhigherriskofinfluenza witharelativerisk(RR) of1.028(95% CI: 1.018, 1.038), 1.041(95% CI: 1.032,1.049), 1.169(95% CI: 1.151,1.188), 1.004(95% CI: 1.003,1.006), and1.134(95% CI: 1.107,1.163), respectively. TherewasanegativeassociationbetweenO(3) and influenza withaRRof0.878(95% CI: 0.866,0.890). CONCLUSIONS: Our findings suggestthatshort-termexposuretoairpollution, exceptforO(3), isassociatedwithgreaterriskforinfluenza. Furtherstudies arenecessarytodecipherunderlyingmechanismsanddesignpreventiveinterventionsandpolicies. https://doi.org/10.1289/EHP12145

目的:分析广州市流感监测数据的时效性,为我市的流感监测以及预警提供依据.方法:研究广州市2017年第1周至2021年第52周的流感监测数据,包括流感报告病例数、流感样病例百分比(ILI％)、病毒阳性率以及流感样病例暴发疫情数,采用时序图比较、计算时间序列交叉相关性以及早期异常报告系统(EARS)进行时效性比较分析.结果:ILI％、病毒阳性率与流感报告病例数以及暴发疫情的交叉相关系数均在滞后(Lag)大于0处取得最大值;ILI％是广州市流感夏季高峰以及其他流感疫情来临预警的较优指标,较流感报告病例数最大滞后6周.病毒阳性率是广州市流感冬季高峰来临较好的预警指标,较流感报告病例数高峰最大滞后周数不超过2周.结论:广州市4种流感监测数据反映的流行趋势大体一致,但它们具有不同的时效性,ILI％与病毒阳性率的预警起始时间大多迟于流感报告病例数以及暴发疫情,这也表明多种监测方法相结合是十分必要的.

Background: Scrub typhus was epidemic in the western Pacific Ocean area and East Asia, scrub typhus epidemic in densely populated areas in southern China. To better understand the association between meteorological variables, Southern Oscillation Index (SOI), and scrub typhus incidence in Guangzhou was benefit to the control and prevention. Methodology/Principal Findings: We collected weekly data for scrub typhus cases and meteorological variables in Guangzhou, and Southern Oscillation Index from 2006 to 2018, and used the distributed lag non-linear models to evaluate the relationships between meteorological variables, SOI and scrub typhus. The median value of each variable was set as the reference. The high-risk occupations were farmer (51.10%), house worker (17.51%), and retiree (6.29%). The non-linear relationships were observed with different lag weeks. For example, when the mean temperature was 27.7°C with1-week lag, the relative risk (RR) was highest as 1.08 (95% CI: 1.01–1.17). The risk was the highest when the relative humidity was 92.0% with 9-week lag, with the RR of 1.10 (95% CI: 1.02–1.19). For aggregate rainfall, the highest RR was 1.06 (95% CI: 1.03–1.11), when it was 83.0 mm with 4-week lag. When the SOI was 19 with 11-week lag, the highest RR was 1.06 (95% CI: 1.01–1.12). Most of the extreme effects of SOI and meteorological factors on scrub typical cases were statistically significant. Conclusion/Significance: The high-risk occupations of scrub typhus in Guangzhou were farmer, house worker, and retiree. Meteorological factors and SOI played an important role in scrub typhus occurrence in Guangzhou. Non-linear relationships were observed in almost all the variables in our study. Approximately, mean temperature, and relative humidity positively correlated to the incidence of scrub typhus, on the contrary to atmospheric pressure and weekly temperature range (WTR). Aggregate rainfall and wind velocity showed an inverse-U curve, whereas the SOI appeared the bimodal distribution. These findings can be helpful to facilitate the development of the early warning system to prevent the scrub typhus.

The authors regret that original version was published with incorrect order of authors. The authors would like to apologise for any inconvenience caused. Positive effects of COVID-19 control measures on pneumonia preventionInternational Journal of Infectious DiseasesVol. 96PreviewThe pandemic of Corona Virus Disease 2019 (COVID-19) is becoming a worldwide disaster. According to the WHO, more than 4,248,389 cases were reported and 294,046 deaths were conformed globally as of 14 May, 2020 (WHO, 2020). It has been reported that humans may be more likely to be infected with different types of viruses through respiratory transmission. Here we report the protective effect to pneumonia while fighting against COVID-19. Full-Text PDF Open Access

Objective: To explore the relationship between meteorological factors and scarlet fever incidence from 2006 to 2017 in Guangzhou, the largest subtropical city of Southern China, and assist public health prevention and control measures. Methods: Data for weekly scarlet fever incidence and meteorological variables from 2006 to 2017 in Guangzhou were collected from the National Notifiable Disease Report System (NNDRS) and the Guangzhou Meteorological Bureau (GZMB). Distributed lag nonlinear models (DLNMs) were conducted to estimate the effect of meteorological factors on weekly scarlet fever incidence in Guangzhou. Results: We observed nonlinear effects of temperature, relative humidity, and wind velocity. The risk was the highest when the weekly mean temperature was 31 degrees C during lag week 14, yielding a relative risk (RR) of 1.48 (95% CI: 1.01-2.17). When relative humidity was 43.5% during lag week 0, the RR was 1.49 (95% CI: 1.04-2.12); the highest RR (1.55, 95% CI: 1.20-1.99) was reached when relative humidity was 93.5% during lag week 20. When wind velocity was 4.4 m/s during lag week 13, the RR was highest at 3.41 (95% CI: 1.57-7.44). Positive correlations were observed among weekly temperature ranges and atmospheric pressure with scarlet fever incidence, while a negative correlation was detected with aggregate rainfall. The cumulative extreme effect of meteorological variables on scarlet fever incidence was statistically significant, except for the high effect of wind velocity. Conclusion: Weekly mean temperature, relative humidity, and wind velocity had double-trough effects on scarlet fever incidence; high weekly temperature range, high atmospheric pressure, and low aggregate rain fall were risk factors for scarlet fever morbidity. Our findings provided preliminary, but fundamental, information that may be useful for a better understanding of epidemic trends of scarlet fever and for developing an early warning system. Laboratory surveillance for scarlet fever should be strengthened in the future. (C) 2019 Elsevier B.V. All rights reserved.

OBJECTIVES:Avian influenza viruses (AIVs) poise significant risk to human health and the poultry industry. We evaluated the transmission risk along the poultry supply chain.METHODS:During October 2015 and July 2016, four rounds of cross-sectional surveys were performed to characterize AIV spread in farms, transport vehicles, slaughterhouses, wholesale and retail live poultry markets (LPMs). Poultry cloacal and oral swabs, environmental swabs, bioaerosol samples and human sera were collected. Poultry and environmental samples were tested for AIVs by rRT-PCR, further subtyped by next generation sequencing. Previous human H9N2 infections were identified by hemagglutination inhibition and microneutralization tests. Logistic regression was fitted to compare AIV transmission risk in different settings.RESULTS:AIVs was detected in 23.9% (424/1771) of the poultry and environmental samples. AIV detection rates in farms, transport vehicles, wholesale and retail LPMs were 4.5%, 11.1%, 30.3% and 51.2%, respectively. 5.2%, 8.3% and 12.8% of the poultry workers were seropositive in farms, wholesale and retail LPMs, respectively. The regression analysis showed that virus detection and transmission risk to human increased progressively along the poultry supply chain.CONCLUSIONS:Strengthening control measures at every level along the poultry supply chain, using a one health approach, is crucial to control AIV circulation.

OBJECTIVE:To evaluate the effect of supply of fresh poultry products on reducing environment contamination of avian influenza virus (AIV) in markets in Guangzhou. METHODS:A total of 40 markets, including 20 selling alive poultry and 20 selling fresh poultry products, were selected randomly in Guangzhou to conduct environment surveillance in 80 poultry stalls every 4 months from July 2014 to April 2015. Four smear samples were collected from different sites of each poultry stall to detect nucleic acid of AIV. The positive samples were further detected for AIV subtype H5, H7 and H9 nucleic acids. RESULTS:Among 40 alive poultry stalls, 95.0% (38/40) kept alive poultry overnight, 25.0% (10/40) were disinfected daily, 95.0% (38/40) were cleaned up weekly, 95.0% (38/40) were closed for one day every month. Among 40 fresh poultry product stalls, 20.0% (8/40) were disinfected daily, 90.0% (36/40) were cleaned up weekly, and 96.0% (38/40) ever sold dressed poultry from alive poultry markets. The positive rate of AIV in alive poultry markets was 40.4% (252/623), higher than that in fresh poultry product markets (32.3%, 197/610), the difference was significant (χ(2)=8.85, P=0.003), and the positive rate of subtype H9 virus in alive poultry markets was 28.6% (178/623), higher than that in fresh poultry product markets (16.2%, 99/610), the difference was significant (χ(2)=26.95, P<0.001). In fresh poultry product markets, the positive rate of AIV in stalls selling dressed poultry was 37.3% (180/482), higher than that in stalls selling no dressed poultry (13.3%, 17/128), the difference was significant (χ(2)=26.78, P<0.001), and the positive rate of subtype H9 virus in stalls selling dressed poultry was 19.1% (92/482), higher than that in stalls selling no dressed poultry (5.5%, 7/128), the difference was significant (χ(2)=13.80, P<0.001). Both the positive rate of AIV and the positive rate of subtype H9 virus were highest in the second round surveillance (October 2014). The differences in AIV and its subtype H5, H7 and H9 virus positive rates of environmental samples from four different sites were not significant, respectively. In the same sample site, the positive rate of subtype H9 virus in alive poultry markets was higher than that in fresh poultry product markets the difference was significant (P<0.05). CONCLUSIONS:The supply of fresh poultry products could effectively reduce the level of environment contamination of AIV in markets. Dressed poultry supplement caused the risk of AIV spread in fresh poultry product markets.

目的 调查广州市活禽档口H7N9禽流感防控设施现况,探讨活禽市场设施和管理中人感染H7N9禽流感病例发生的危险因素.方法 按各区进行分层随机抽样,抽取72个活禽市场,每个市场根据档口结构调查1～3个活禽档口,共抽取127个档口,均为非病例暴露市场.另选取病例暴露市场16个,调查其活禽档口30个.观察记录活禽档口通风设施、内部分隔及防控措施落实情况.结果 非中心城区档口在将禽类“运离市场”比例(25.86％)高于中心城区档口(7.25％) (x=8.230,P=0.004).在通风设备使用方面,病例暴露市场档口(93.33％)使用搅拌型通风器械比例多于非病例暴露市场档口(68.50％)(x2=6.420,P=0.011);病例暴露市场档口将禽类“留在市场存栏”比例(56.67％)高于非病例暴露市场档口(28.35％) (x2=8.704,P=0.003).结论 搅拌型通风器械和活禽留在市场存栏是人感染H7N9禽流感病例发生的危险因素.广州市活禽市场档口存在较多不利于禽流感防控的因素,政府须继续加强对于活禽档口设施和禽流感防控管理.

Background: Live poultry traders (LPTs) have greater risk to avian influenza due to occupational exposure to poultry. This study investigated knowledge, attitudes and practices of LPTs relating to influenza A (H7N9). Methods: Using multi-stage cluster sampling, 306 LPTs were interviewed in Guangzhou by a standardized questionnaire between mid-May to June, 2013. Hierarchical logistic regression models were used to identify factors associated with preventive practices and attitudes towards various control measures implemented in live poultry markets against H7N9. Results: Only 46.1% of the respondents recognized risks associated with contacts with bird secretions or droppings, and only 22.9% perceived personally “likely/very likely” to contract H7N9 infection. Around 60% of the respondents complied with hand-washing and wearing gloves, and only 20% reported wearing face masks. Only 16.3% of the respondents agreed on introducing central slaughtering of poultry. Being younger, involving in slaughtering poultry, having longer working hours, less access to H7N9-related information and poorer knowledge, and perceiving lower personal susceptibility to H7N9 infection were negatively associated with preventive practices. Comparing with previous studies conducted when human cases of H5N1 avian influenza infection was first identified in Guangdong, LPTs’ perceived susceptibility to novel influenza viruses increased significantly but acceptance for central slaughtering of poultry remained low. Conclusions: Information on avian influenza provided through multiple communication tools may be necessary to promote knowledge among poultry traders. Familiarity with risk may have led to the lower perceived vulnerability to avian influenza and less protective actions among the LPTs particularly for those involving more risky exposure to live poultry. Reasons for the consistently low acceptance for central slaughtering of poultry await further exploration.

Two sets of cross-sectional surveys were conducted among the general public and live poultry traders (LPTs) during January-February, 2014, to monitor attitudes toward human cases of avian influenza A(H7N9)-related control measures among these 2 parties in Guangzhou, China. We found generally high support for regular market rest days among the general public and LPTs, but only limited support for permanent central slaughtering of poultry. LPTs' support for relevant control measures declined after the citywide wet market closure.

Objective To understand the knowledge,attitude and practice status about avian influenza A(H7N9)among people with occupational exposure to wild birds in Guangzhou and provide evidence for making up health education measures.Methods A total of 179 people with occupational exposure to wild birds,including 97 close contacts,were investigated.Results The awareness rate of H7N9 avian among close contacts and non-close contacts was 69.81%and 62.20%respectively.Television,newspapers,and internet were the main channels to learn about H7N9 avian influenza related knowledge.The percentages of wearing of masks,gloves,work clothes,waterproof shoes or shoe covers and work hats were 92.78%,84.54%,83.51%,83.51%and 71.13%respectively.The close contact did not take comprehensive safeguard procedures when they treated sick or dead wild birds.Up to 97.94%of close contacts and 96.34%of non-close contacts disposed sick or dead wild birds correctly.The immunization rate of influenza vaccine in close contacts and in non-close contacts was 35.05%and 15.85%respectively during past year,while the percentage of those who were willing to have free vaccination was 76.29%and 78.05%respectively.Conclusion The awareness of H7N9 avian influenza among people with occupational exposure to wild birds place in Guangzhou was poor.The rate of taking comprehensive protection among them was very low.The percentage of those who were willing to have free vaccination was significantly higher than the vaccination rate during past year.It is suggested that the education about H7N9 avian influenza prevention should be strengthened in this population with different ways.

ABSTRACT We present immunogenicity data on the routine vaccination of 103 health care personnel during the 2009 H1N1 national vaccination campaign. The seroprotection rate (percentage of samples with hemagglutination inhibition titers of ≥1:40) was 83.2% at 30 days postvaccination, lower than those obtained in previously published controlled trials. Low baseline antibody levels and an increase in seroprotection in a negative-control cohort suggest that the virus remains prevalent.