Antimicrobial Resistance Analysis and Whole-Genome Sequencing of Salmonella Isolates from Environmental Sewage - Guangzhou City, Guangdong Province, China, 2022-2023.

What is already known about this topic?: S.1,4,[5],12:i:- and S. Rissen are emerging serotypes of Salmonella that require close monitoring for antimicrobial resistance and containment of their spread. What is added by this report?: The study aimed to identify antimicrobial resistance genes (ARGs) in S.1,4,[5],12:i:- and S. Rissen strains isolated from environmental sewage in Guangzhou City, Guangdong Province, China. A phylogenetic tree was constructed using single nucleotide polymorphism data to assess genetic relatedness among strains, offering insights for Salmonella infection outbreak investigations in the future. What are the implications for public health practice?: It is crucial to implement strategies, such as integrating different networks, to control the spread of drug-resistant Salmonella. Novel technologies must be utilized to disinfect sewage and eliminate ARGs. Ensuring food safety and proper sewage disinfection are essential to curb the dissemination of Salmonella.

Transmission chains of the first local outbreak cause by Delta VariantB.1.617.2 COVID-19 in Guangzhou, Southern China.

BACKGROUND: The first local outbreak of Delta Variant B.1.617.2 COVID-19 of China occurred in Guangzhou city, south China, in May 2021. This study analyzed the transmission chains and local cluster characteristics of this outbreak, intended to provide information support for the development and adjustment of local prevention and control strategies. METHODS: The transmission chains and local cluster characteristics of 161 local cases in the outbreak were described and analyzed. Incubation period, serial interval and generation time were calculated using the exact time of exposure and symptom onset date of the cases. The daily number of reported cases and the estimated generation time were used to estimate the effective reproduction number (Rt). RESULTS: We identified 7 superspreading events who had more than 5 next generation cases and their infected cases infected 70.81%(114/161) of all the cases transmission. Dining and family exposure were the main transmission routes in the outbreak, with 29.19% exposed through dining and 32.30% exposed through family places. Through further analysis of the outbreak, the estimated mean incubation period was 4.22 (95%CI: 3.66-4.94) days, the estimated mean generation time was 2.60 (95%CI: 1.96-3.11) days, and the estimated Rt was 3.29 (95%CI: 2.25-5.07). CONCLUSIONS: Classification and dynamically adjusted prevention and control measures had been carried out according to analysis of transmission chains and epidemical risk levels, including promoting nucleic acid screening at different regions and different risk levels, dividing closed-off area, controlled area according to the risk of infection, raising the requirements of leaving Guangzhou. By the above control measures, Guangzhou effectively control the outbreak within 28 days without implementing a large-scale lockdown policy.

Cold-Chain-Food-Related COVID-19 Surveillance in Guangzhou between July 2020 and December 2022.

OBJECTIVE: To monitor severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA contamination in samples linked to imported cold-chain food and assess the situation from the implementation of a centralized supervision warehouse system in Guangzhou, Guangdong Province, China. METHODS: Swabs of workers and frozen-food-related samples were collected between July 2020 and December 2023 in Guangzhou, Guangdong Province. SARS-CoV-2 RNA was extracted and analyzed by a real-time quantitative polymerase chain reaction using the commercially available SARS-CoV-2 nucleic acid test kit. The risk level and food source were monitored simultaneously. RESULTS: A total of 283 positive cold-chain events were found in Guangzhou since the first cold-chain-related event of the coronavirus disease 2019 pandemic was identified in July 2020. Most positive samples were a low-to-medium risk, and the cycle threshold value was >30. No live virus was detected, and no staff came into direct contact with a live virus. In total, 87.63% of positive events were identified through sampling and testing at the centralized food warehouse. CONCLUSION: Cold-chain food has a relatively low risk of transmitting SARS-CoV-2. Centralized food storage can be used as an effective method to control this risk, and this measure can also be used for other food-related, contact-transmitted diseases.

Transmission and containment of the SARS-CoV-2 Delta variant of concern in Guangzhou, China: A population-based study.

BACKGROUND: The first community transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant of concern (VOC) in Guangzhou, China occurred between May and June 2021. Herein, we describe the epidemiological characteristics of this outbreak and evaluate the implemented containment measures against this outbreak. METHODOLOGY/PRINCIPAL FINDINGS: Guangzhou Center for Disease Control and Prevention provided the data on SARS-CoV-2 infections reported between 21 May and 24 June 2021. We estimated the incubation period distribution by fitting a gamma distribution to the data, while the serial interval distribution was estimated by fitting a normal distribution. The instantaneous effective reproductive number (Rt) was estimated to reflect the transmissibility of SARS-CoV-2. Clinical severity was compared for cases with different vaccination statuses using an ordinal regression model after controlling for age. Of the reported local cases, 7/153 (4.6%) were asymptomatic. The median incubation period was 6.02 (95% confidence interval [CI]: 5.42-6.71) days and the means of serial intervals decreased from 5.19 (95% CI: 4.29-6.11) to 3.78 (95% CI: 2.74-4.81) days. The incubation period increased with age (P<0.001). A hierarchical prevention and control strategy against COVID-19 was implemented in Guangzhou, with Rt decreasing from 6.83 (95% credible interval [CrI]: 3.98-10.44) for the 7-day time window ending on 27 May 2021 to below 1 for the time window ending on 8 June and thereafter. Individuals with partial or full vaccination schedules with BBIBP-CorV or CoronaVac accounted for 15.3% of the COVID-19 cases. Clinical symptoms were milder in partially or fully vaccinated cases than in unvaccinated cases (odds ratio [OR] = 0.26 [95% CI: 0.07-0.94]). CONCLUSIONS/SIGNIFICANCE: The hierarchical prevention and control strategy against COVID-19 in Guangzhou was timely and effective. Authorised inactivated vaccines are likely to contribute to reducing the probability of developing severe disease. Our findings have important implications for the containment of COVID-19.

The Trends of Psychological Status of People Entering from High-Risk Areas of COVID-19 Coronavirus During the Quarantine in Dedicated Hotels: A Longitudinal Survey Study from Guangzhou, China.

BACKGROUND: The quarantine in dedicated hotels has become an inevitable safety measure due to the frequent cross-border travel since the outbreak of COVID-19. The aim of the present study was to explore the trends in the psychological status of individuals entering from high-risk areas of COVID-19 coronavirus while quarantining in dedicated hotels. METHODS: A total of 591 individuals who isolated in dedicated hotels were recruited between March and June 2020. Participants self-reported mental symptoms [Self-rating Anxiety Scale (SAS) and Self-rating Depression Scale (SDS)] every three days during the quarantine. A mixed-effects linear regression model was used to assess the trends. RESULTS: Participants reporting anxiety and depression symptoms at least one time during quarantine accounted for 4.5% and 18.4%, respectively. Their psychological status was alleviated during some first 9 days, and then it slightly deteriorated, which was suggested by SAS and SDS scores that were negatively correlated with the days of quarantine (T) (adjusted coefficient [ß] -0.81, 95% CI -1.00 to -0.62; and ß -0.75, 95% CI -0.97 to -0.53, respectively), and were positively correlated with the square of T (ß 0.04, 95% CI 0.02 to 0.06; and ß 0.04, 95% CI 0.02 to 0.06, respectively). The unemployed and 18~30-year-old participants were prone to greater levels of psychological distress. No significant difference in the trend of mental health was found among different subgroups. CONCLUSION: The mental health of the people entering Guangzhou from high-risk areas of COVID-19 coronavirus resulted positive during the early period of quarantine in dedicated hotels, after which it deteriorated. The psychological status of individuals should be closely monitored at the beginning and after more than 9 days of quarantine, especially for individuals who are unemployed and 18~30-year-old ones.

Probable Causes and Risk Factors for Positive SARS-CoV-2 Testing in Recovered Patients: Evidence From Guangzhou, China.

Some patients retested positive for SARS-CoV-2 following negative testing results and discharge. However, the potential risk factors associated with redetectable positive testing results in a large sample of patients who recovered from COVID-19 have not been well-estimated. A total of 745 discharged patients were enrolled between January 30, 2020, and September 9, 2020, in Guangzhou, China. Data on the clinical characteristics, comorbidities, drug therapy, RT-PCR testing, and contact modes to close contacts were collected. Patients who tested positive for SARS-CoV-2 after discharge were confirmed by guidelines issued by China. The repositive rate in different settings was calculated. Among 745 discharged patients, 157 (21.1%; 95% CI, 18.2-24.0%) tested repositive and the repositive rate was 16.8% (95% CI, 14.1-24.0%) for nasopharyngeal swabs and 9.7% (95% CI, 7.0-12.5%) for anal swabs. Among them, 55 (35.0%) were asymptomatic, 15 (9.6%) had mild symptoms, 83 (52.9%) had moderate symptoms, and 4 (2.6%) had severe symptoms at the first admission. The days from discharge to repositivity was 8.0 (IQR, 8.0-14.0). Most repositive patients were without clinical symptoms, and lymphocyte cell counts were higher than before being discharged. The likelihood of repositive testing for SARS-CoV-2 RNA was significantly higher among patients who were of younger age (OR, 3.88; 95% CI, 1.74-8.66, 0-17 years old), had asymptomatic severity (OR, 4.36; 95% CI, 1.47-12.95), and did not have clinical symptoms (OR, 1.89; 95% CI, 1.32-2.70, without fever). No other positive patients emerged within the families or close contacts of repositive patients. Our findings support prolonged but intermittent viral shedding as the probable cause for this phenomenon; we need to familiarize with the possibility that the virus will remain endemic.

Transmission dynamics and successful control measures of SARS-CoV-2 in the mega-size city of Guangzhou, China.

ABSTRACT: The severe acute respiratory syndrome coronavirus 2 has caused a worldwide pandemic. Control measures differ among countries and have a varying degree of effectiveness, which requires assessment. To evaluate the effectiveness of public health interventions of the coronavirus disease 2019 (COVID-19) in Guangzhou by 3 periods according to interventions: January 7 to 22 (no intervention), January 23 to February 23 (implemented intensive interventions), and February 24 to May 17 (the normalization mode of COVID-19 prevention and control).We collected the information of 745 COVID-19 patients and their close contacts as well as control measures in Guangzhou from January 7 to May 17, 2020. We estimated the epidemiological characteristics, disease spectrum of COVID-19 cases, key time-to-event intervals, and effective reproduction number over the 3 periods. The basic reproduction number of severe acute respiratory syndrome coronavirus 2 was also calculated over period 1.Approximately 45.8%, 49.8%, and 4.4% of cases from close contacts were asymptomatic, symptomatic, and severe, respectively. The median incubation period was 5.3 days (the percentiles of 2.5-97.5, 1.5-18.4 days) and the median serial interval fitted with gamma distribution was 5.1 days (the percentiles of 2.5-97.5, 0.8-15.9 days). The estimated median of onset-to-quarantined time in Period 1 to 3 were 7.5, 3.4, and 2.9 days (the percentiles of 2.5-97.5, 2.1-14.2, 3.9-14.7, and 6.0-20.0 days) respectively and the median of onset-to-confirmation time in period 1 to 3 were 8.9, 4.9 and 2.4 days (the percentiles of 2.5-97.5, 2.6-16.6, 0.9-14.6, and 0.5-11.8 days). In period 1, the reproduction number was 0.9 (95% confidence interval, 0.5-1.4) and fluctuated below 1.0 before January 22 except for January 14. The effective reproduction number gradually decreased in the period 2 with the lowest point of 0.1 on February 20, then increased again since March 27 and reach a spike of 1.8 on April 12. The number decreased to below 1.0 after April 17 and decreased further to <0.2 after May 7 in the period 3.Under prospective dynamic observation, close contacts turned into infected cases could provide a spectrum of COVID-19 cases from real-world settings. The lockdown of Wuhan and closed-loop management of people arriving Guangzhou were effective in halting the spread of the COVID-19 cases to Guangzhou. The spread of COVID-19 was successfully controlled in Guangzhou by social distancing, wearing a face mask, handwashing, disinfection in key places, mass testing, extensive contact tracing, and strict quarantine of close contacts.

Sewage as a Possible Transmission Vehicle During a Coronavirus Disease 2019 Outbreak in a Densely Populated Community: Guangzhou, China, April 2020.

BACKGROUND: Sewage transmission of SARS-CoV-2 has never been demonstrated. During a COVID-19 outbreak in Guangzhou, China in April 2020, we investigated the mode of transmission. METHODS: We collected clinical and environmental samples from quarantined residents and their environment for RT-PCR testing and genome sequencing. A case was a resident with a positive RT-PCR test regardless of symptoms. We conducted a retrospective cohort study of all residents of cases' buildings to identify risk factors. RESULTS: We found 8 cases (onset: 5-21 April). During incubation period, cases 1 and 2 frequented market T where a COVID-19 outbreak was ongoing; cases 3-8 never visited market T, lived in separate buildings and never interacted with cases 1 and 2. Working as a janitor or wastepicker (RR = 13; 95% CIexact, 2.3-180), not changing to clean shoes (RR = 7.4; 95% CIexact, 1.8-34) and handling dirty shoes by hand (RR = 6.3; 95% CIexact, 1.4-30) after returning home were significant risk factors. RT-PCR detected SARS-CoV-2 in 19% of 63 samples from sewage puddles or pipes, and 24% of 50 environmental samples from cases' apartments. Viruses from the squat toilet and shoe-bottom dirt inside the apartment of cases 1 and 2 were homologous with those from cases 3-8 and the sewage. Sewage from the apartment of cases 1 and 2 leaked out of a cracked pipe onto streets. Rainfall after the onset of cases 1 and 2 flooded the streets. CONCLUSIONS: SARS-CoV-2 might spread by sewage, highlighting the importance of sewage management during outbreaks.

Air and surface contamination in non-health care settings among 641 environmental specimens of 39 COVID-19 cases.

Little is known about the SARS-CoV-2 contamination of environmental surfaces and air in non-health care settings among COVID-19 cases. We explored the SARS-CoV-2 contamination of environmental surfaces and air by collecting air and swabbing environmental surfaces among 39 COVID-19 cases in Guangzhou, China. The specimens were tested on RT-PCR. The information collected for COVID-19 cases included basic demographic, clinical severity, symptoms at onset, radiological testing, laboratory testing and hospital admission. A total of 641 environmental surfaces and air specimens were collected among 39 COVID-19 cases before disinfection. Among them, 20 specimens (20/641, 3.1%) were tested positive from 9 COVID-19 cases (9/39, 23.1%), with 5 (5/101, 5.0%) positive specimens from 3 asymptomatic cases, 5 (5/220, 2.3%) from 3 mild cases, and 10 (10/374, 2.7%) from 3 moderate cases. All positive specimens were collected within 3 days after diagnosis, and 10 (10/42, 23.8%) were found in toilet (5 on toilet bowl, 4 on sink/faucet/shower, 1 on floor drain), 4 (4/21, 19.0%) in anteroom (2 on water dispenser/cup/bottle, 1 on chair/table, 1 on TV remote), 1 (1/8, 12.5%) in kitchen (1 on dining-table), 1 (1/18, 5.6%) in bedroom (1 on bed/sheet pillow/bedside table), 1 (1/5, 20.0%) in car (1 on steering wheel/seat/handlebar) and 3 (3/20, 21.4%) on door knobs. Air specimens in room (0/10, 0.0%) and car (0/1, 0.0%) were all negative. SARS-CoV-2 was found on environmental surfaces especially in toilet, and may survive for several days. We provided evidence of potential for SARS-CoV-2 transmission through contamination of environmental surfaces.

Kinetics of IgG Antibodies in Previous Cases of Dengue Fever-A Longitudinal Serological Survey.

Guangzhou is believed to be the most important epicenter of dengue outbreaks in southern China. In this study, a longitudinal serological investigation of previous cases of dengue fever in Guangzhou was conducted to explore the persistence of IgG antibodies and related factors affecting the changes of antibody level. We recruited 70 dengue virus type 1 (DENV-1) primary infection cases at two years post infection for serological investigation and conducted a second follow-up in the 5th year of prognosis. An enzyme-linked immunosorbent assay (ELISA) for DENV IgG antibody was examined in all study subjects. Potential factors associated with the concentration of serum total IgG antibody were determined by the generalized estimation equation (GEE). No significant difference in serum total IgG antibody positive rate between two follow-ups was observed (χ2 = 3.066, p = 0.080). However, there was a significant difference in the concentration of serum total IgG antibody between the two follow-ups (Z = 7.154, p < 0.001). The GEE showed that the antibody level in the five-year prognosis was mainly affected by the antibody level in the two-year prognosis (OR: 1.007, 95%CI: 1.005-1.009). In conclusion, the serum IgG antibodies of previous dengue fever cases can persist for a long time.

The increasing menace of dengue in Guangzhou, 2001-2016: the most important epicenter in mainland China.

BACKGROUND: Dengue is the most prevalent mosquito-borne disease in the world, with China affected seriously in recent years. 65.8% of dengue cases identified in mainland China since 2005 were reported from the city of Guangzhou. METHODS: In this study, we described the incidence rate and distribution of dengue cases using data collected form National Notifiable Infectious Disease Reporting Information System data in Guangzhou for 2001 to 2016. All dengue cases were investigated using standardized questionnaire. RESULTS: A total of 42,469 dengue cases were reported, with an average annual incidence rate of 20.99 per 100,000 resident population. Over this time period, the incidence rate of indigenous cases increased. Dengue affected areas also expanded sharply geographically from 58.1% of communities affected during 2001-2005 to 96.4% of communities affected in 2011-2016. Overall 95.30% of the overseas imported cases were reported during March and December, while 99.79% of indigenous cases were reported during July and November. All four dengue virus serotypes were identified both in imported cases and indigenous cases. The Aedes albopictus mosquito was the only vector for dengue transmission in the area. CONCLUSIONS: Guangzhou has become the dengue epicenter in mainland China. Control strategies for dengue should be adjusted to the epidemiological characteristics above and intensive study need to be conducted to explore the factors that driving the rapid increase of dengue.

Epidemiological and Evolutionary Analysis of Dengue-1 Virus Detected in Guangdong during 2014: Recycling of Old and Formation of New Lineages.

The incidence of dengue is increasing in Guangdong, China, with the largest outbreak to date in 2014. Widespread awareness of epidemiological and molecular characteristics of the dengue virus (DENV) is required. In 2014, we isolated the virus from patients and sequenced its genome. The sequences of DENV isolated from Guangdong and other countries screened since 2005 were studied to establish molecular evolutionary databases along with epidemiological data to explore its epidemiological, phylogenetic, and molecular characteristics. Causes underlying the occurrence of the dengue epidemic included importation and localization of the virus. The number of indigenous cases significantly exceeded that of imported cases. Dengue virus 1 is the most important serotype and caused the long-term epidemic locally. Based on the data available since 2005, DENV1 was divided into three genotypes (I, IV, and V). Only genotypes I and V were detected in 2014. In 2014, an epidemic involving old lineages of DENV1 genotype V occurred after 2 years of silence. The genotype was previously detected from 2009 to 2011. Genotype I, which caused recent epidemics, demonstrated a continuation of new lineages, and a predictive pattern of molecular evolution since 2005 among the four lineages was present. The DENV isolated from Guangdong was closely related to those causing large-scale epidemics in neighboring countries, suggesting the possibility of its import from these countries. The lack of sufficient epidemiological data and evidence on the local mosquito-borne DENV emphasizes the importance of studying the molecular evolutionary features and establishing a well-established phylogenetic tree for dengue prevention and control in Guangdong.

Dengue Underestimation in Guangzhou, China: Evidence of Seroprevalence in Communities With No Reported Cases Before a Large Outbreak in 2014.

OBJECTIVE: Dengue has become a serious public health problem in southern China particularly with a record-breaking outbreak in 2014. Serological evidence from areas with no known dengue cases reported prior to 2014 could provide information on possible unrecognized circulation of dengue virus (DENV) before this outbreak. METHOD: Between March and May 2015, we performed a cross-sectional serosurvey using a stratified random sampling method among individuals aged 1-84 years-old in 7 communities in Guangzhou with no reported dengue cases before 2014. Sera of subjects were initially screened with the indirect DENV IgG enzyme-linked immunosorbent assay, and positive samples were further tested by the indirect immunofluorescence assay to identify specific serotypes. RESULTS: A total of 850 subjects had complete information available. The overall seroprevalence against DENV was 6.59% (56 of 850; 95% CI, 4.92%-8.26%). The seroprevalence increased with age in general (3.86%, 4.58%, 8.72%, 7.22%, and 10.69% among participants in ≤14, 15-29, 30-44, 45-59 and ≥60 years age group, respectively). Living in rural or peri-urban communities and longer years of residence therein were risk factors for higher seroprevalence, whereas wearing long sleeves and pants when outdoors was associated with lower seroprevalence. Of the total subjects, 55.36% (31 of 56) sera were successfully identified with specific serotypes, with 12.90% (4 of 31) being coinfected with 2 serotypes. CONCLUSIONS: Dengue transmission in the study communities had occurred prior to the 2014 massive outbreak, possibly for many years, but went undiagnosed and unreported. A proportion of the study population experienced secondary infection as different serotypes of DENV increased the risk for severe diseases. Active surveillance and education of both healthcare providers and the general population should be conducted in areas at risk for dengue emergence in order to better reduce disease burden.

Effect of meteorological factors on scarlet fever incidence in Guangzhou City, Southern China, 2006-2017.

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 °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 rainfall 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.

Willingness and influential factors of parents to vaccinate their children with novel inactivated enterovirus 71 vaccines in Guangzhou, China.

Hand, foot and mouth disease (HFMD) primarily affects children younger than 5 years of age. Recently, HFMD has ranked as the top notifiable infectious disease in China. In December 2015, China approved two novel inactivated enterovirus 71 vaccines (EV71 vaccines) for HFMD. Parents' acceptance is often essential for vaccination program success. The goal of this study was to identify willingness and influential factors to vaccinate among parents of kindergarteners in Guangzhou, China. A cross-sectional survey of face-to-face interviews was conducted from March to July 2016. Fifty-five kindergartens were randomly selected from 11 districts of Guangzhou. An anonymous self-designed questionnaire was used to investigate awareness, knowledge and attitude towards HFMD and EV71 vaccines. A total of 868 parents participated in the survey. Mean(±standard deviation) knowledge score of HFMD was 6.32(±1.70). Approximately 32.03% of parents had heard of the EV71 vaccines with 22.58% receiving information before this study. Nearly 44.24% of parents showed willingness to vaccinate their children. Previously receiving EV71 vaccine-related information [adjusted odds ratio (aOR) = 1.48, 95% confidence interval (CI): 1.04-2.11], no fear of adverse effects (aOR = 4.25, 95%CI: 2.77-6.53), perceived susceptibility of children to HFMD (aOR = 2.15, 95%CI: 1.42-3.25) and children not previously diagnosed with HFMD (aOR = 1.56, 95%CI: 1.07-2.27) were positively associated with EV71 vaccination acceptability. However, parental education background (aOR = 0.54, 95%CI: 0.37-0.80) was negatively correlated with vaccination acceptability. Our study provides baseline information for future vaccination campaigns to help improve the EV71 vaccine uptake rate. Special efforts are urgently needed to improve the awareness and knowledge of EV71 vaccines in China.

Factors associated with clinical outcome in 25 patients with avian influenza A (H7N9) infection in Guangzhou, China.

BACKGROUND: Guangzhou reported its first laboratory-confirmed case of influenza A (H7N9) on January 10, 2014. A total of 25 cases were reported from the first wave of the epidemic until April 8, 2014. The fatality rate was much higher than in previous reports. The objective of the current work was to describe the clinical and epidemiological characteristics of A (H7N9) patients in Guangzhou and explore possible reasons for the high fatality rate. METHODS: Clinical and epidemiological information regarding A (H7N9) cases in Guangzhou was collected through review of medical records and field research. Data regarding clinical and laboratory features, treatment, and outcomes were extracted. RESULTS: Of the 25 patients, 84 % (21/25) had one or more underlying diseases. Fifteen patients (60.0 %) developed moderate to severe acute respiratory distress syndrome (ARDS), and 14 (56 %) died of the ARDS or multiorgan failure. Patients with longer delay between onset of illness and initiation of oseltamivir treatment were more likely to develop ARDS. Elevated C-creative protein, aspartate aminotransferase, creatine kinase, and lymphocytopenia predicted a higher risk of developing ARDS. CONCLUSIONS: The presence of underlying diseases and clinical complications predicted poor clinical outcome. Early oseltamivir treatment was associated with a reduced risk of developing ARDS.

[Effects of resting days on live poultry markets in controlling the avian influenza pollution].

OBJECTIVE: To analyze the results of nine-round environmental specimen surveillance programs in five live poultry markets pre-, during and post the 'closing days' and to evaluate the effects of 'closing days' on live poultry markets regarding the control against avian influenza pollution. METHODS: In January 2014, control measures including culling poultry, completely cleaning and disinfecting and a 'three-day-closing' measure were conducted in five live poultry markets which were found positive for H7N9 nucleic acid in the 1(st) round environmental specimen surveillance program. Second surveillance program was conducted after a thorough disinfection campaign was launched. Several times surveillance were conducted in one week, after the markets were reopened. RT-PCR was used to test the nucleic acid of HA, H5, H7 and H9 viruses. RESULTS: 654 specimens from the environment were collected and tested. During the first round surveillance program, positive rates for influenza A and H5/H7/H9 nucleic acid of poultry stalls appeared to be 94.44% and 61.11% respectively. The positive rates of poultry stalls reduced to 0 after the disinfection campaign but increased again after the markets reopened. The positive rate for influenza A of poultry stalls slightly increased from 50.00% in the third surveillance to 72.22% in the ninth surveillance (P > 0.05). The positive rate for H5/H7/H9 of poultry stalls showed a significantly increasing trend, from 0 in the third surveillance to 44.44% in the ninth surveillance (P < 0.01). The positive rates for influenza A and H5/H7/H9 nucleic acid of specimens were 28.89% and 17.78% respectively. The positive rate of specimens reduced to 0 after disinfection while increased again after reopening of the markets. The positive rate for influenza A of specimens slightly increased from 19.67% in the third surveillance to 27.54% in the ninth surveillance programs (P > 0.05). The positive rate for H5/H7/H9 of specimen showed a significant increasing trend, from 0 in the third surveillance to 8.70% in the ninth-round surveillance programs (P < 0.01). The positive rate for influenza A was the highest for slaughter- related specimens of 22.4% (35/156). The positive rates for influenza A from sewage and drinking water being collected on the later stage after the markets reopened (25.9%, 12.4%)were higher than those on the early stage (8.3%, 8.6%) (P > 0.05). The positive rate for influenza A of poultry stalls with overnight poultry storage (91.7%) was significant higher than that of poultry stalls without the overnight storage (33.3%). The positive rate for influenza A of poultry stalls in which simultaneously selling different kinds of poultry (85.7%) was significant higher than that of poultry stalls in which selling only one kind of poultry at one time (25.0%) (P < 0.05). CONCLUSION: Slaughter in live poultry markets posed a large risk of pollution diffusion. Sewage and drinking water showed an accumulation effect for avian influenza virus. Overnight poultry storage and selling different kinds of poultry at one time at the poultry stalls seemed the risk factors for avian influenza virus transmission. Complete cleaning, disinfecting and several 'closing days' for live poultry markets seemed effective in eliminating avian influenza virus. Once the markets were reopened, they seemed to be soon polluted again.

Detection of avian influenza A(H7N9) virus from live poultry markets in Guangzhou, China: a surveillance report.

PURPOSE: A virologic surveillance program for A(H7N9) virus was conducted from April 15, 2013 to February 14, 2014 in Guangzhou, aiming to clarify the geographical distribution of A(H7N9) viruses among live poultry markets (LPMs) and poultry farms in Guangzhou. Virological and serological surveys of poultry workers were also conducted to evaluate the risk of poultry-to-human transmission of the A(H7N9) virus. METHODS: 36 retail LPMs, 6 wholesale LPMs and 8 poultry farms were involved in our surveillance program. About 20 live poultry and environmental samples were obtained from each surveillance site at every sampling time. Different environmental samples were collected to represent different poultry-related work activities. RT-PCR and virus culture were performed to identify the A(H7N9) virus. Hemagglutinin inhibition assay and RT-PCR were conducted to detect possible A(H7N9) infection among poultry workers. RESULTS: A total of 8900 live poultry and environmental samples were collected, of which 131(1.5%) were tested positive for A(H7N9) virus. 44.4% (16/36) of retail LPMs and 50.0% (3/6) of wholesale LPMs were confirmed to be contaminated. No positive samples was detected from poultry farms. A significant higher positive sample rate was found in environmental samples related to poultry selling (2.6%) and slaughtering (2.4%), compared to poultry holding (0.9%). Correspondingly, A(H7N9) viruses were isolated most frequently from slaughter zone. In addition, 316 poultry workers associated with the 19 contaminated-LPMs were recruited and a low seroprevalence (1.6%) of antibody against A(H7N9) virus was detected. An asymptomatic A(H7N9) infection was also identified by RT-PCR. CONCLUSIONS: Our study highlights the importance of conducting effective surveillance for A(H7N9) virus and provides evidence to support the assumption that slaughtering is the key process for the propagation of A(H7N9) virus in retail LPMs. Moreover, the ability of A(H7N9) virus to cross species barrier is proved to be still limited.

Asymptomatic, mild, and severe influenza A(H7N9) virus infection in humans, Guangzhou, China.

Targeted surveillance for influenza A(H7N9) identified 24 cases of infection with this virus in Guangzhou, China, during April 1, 2013-March 7, 2014. The spectrum of illness ranged from severe pneumonia to asymptomatic infection. Epidemiologic findings for 2 family clusters of infection highlight the importance of rigorous close contact monitoring.