Surveillance of West Nile virus infection in Kashgar Region, Xinjiang, China, 2013-2016.

West Nile virus (WNV) was first isolated in mainland China from mosquitoes in Jiashi County, Kashgar Region, Xinjiang in 2011, following local outbreaks of viral meningitis and encephalitis caused by WNV. To elaborate the epidemiological characteristics of the WNV, surveillance of WNV infection in Kashgar Region, Xinjiang from 2013 to 2016 were carried out. Blood and CSF samples from surveillance human cases, blood of domestic chicken, cattle, sheep and mosquitoes in Kashgar Region were collected and detected. There were human 65 WNV Immunoglobulin M (IgM) antibody positive cases by ELISA screening, 6 confirmed WNV cases by the plaque reduction neutralization test (PRNT) screening. These cases occurred mainly concentrated in August to September of each year, and most of them were males. WNV-neutralizing antibodies were detected in both chickens and sheep, and the positive rates of neutralizing antibodies were 15.5% and 1.78%, respectively. A total of 15,637 mosquitoes were collected in 2013-2016, with Culex pipiens as the dominant mosquito species. Four and 1 WNV-positive mosquito pools were detected by RT-qPCR in 2013 and 2016 respectively. From these data, we can confirm that Jiashi County may be a natural epidemic foci of WNV disease, the trend highlights the routine virology surveillance in WNV surveillance cases, mosquitoes and avian should be maintained and enhanced to provide to prediction and early warning of outbreak an epidemic of WNV in China.

Active case finding with case management: the key to tackling the COVID-19 pandemic.

COVID-19 was declared a pandemic by WHO on March 11, 2020, the first non-influenza pandemic, affecting more than 200 countries and areas, with more than 5·9 million cases by May 31, 2020. Countries have developed strategies to deal with the COVID-19 pandemic that fit their epidemiological situations, capacities, and values. We describe China's strategies for prevention and control of COVID-19 (containment and suppression) and their application, from the perspective of the COVID-19 experience to date in China. Although China has contained severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and nearly stopped indigenous transmission, a strong suppression effort must continue to prevent re-establishment of community transmission from importation-related cases. We believe that case finding and management, with identification and quarantine of close contacts, are vitally important containment measures and are essential in China's pathway forward. We describe the next steps planned in China that follow the containment effort. We believe that sharing countries' experiences will help the global community manage the COVID-19 pandemic by identifying what works in the struggle against SARS-CoV-2.

Evaluating the importation of yellow fever cases into China in 2016 and strategies used to prevent and control the spread of the disease.

During the yellow fever epidemic in Angola in 2016, cases of yellow fever were reported in China for the first time. The 11 cases, all Chinese nationals returning from Angola, were identified in March and April 2016, one to two weeks after the peak of the Angolan epidemic. One patient died; the other 10 cases recovered after treatment. This paper reviews the epidemiological characteristics of the 11 yellow fever cases imported into China. It examines case detection and disease control and surveillance, and presents recommendations for further action to prevent additional importation of yellow fever into China.

Survey of Traveler's Diarrhea: Epidemiology and Testing Reveal the Source.

OBJECTIVE: To understand the causes and transmission routes of, as well as risk factors, for a Salmonella outbreak in a tour group. METHOD: A retrospective cohort design was used to conduct an epidemiological field investigation. Real-time fluorescent quantitative PCR, bacterial culture, and serological identification methods were used for pathogen detection and identification. RESULT: There were 7 cases of illness, and the attack rate was 46.67%. The onset date was concentrated on May 9 and 10. All cases were found in the tour group, and no cases occurred in the nontour group. The results of this retrospective cohort study showed that the consumption of boiled eggs for breakfast on May 9 was a common factor (R 2 = 6.67, P=0.023). Salmonella enteritidis was identified from the patients' stool and vomit. CONCLUSION: The food poisoning epidemic was caused by Salmonella enteritidis. In the summer and autumn, attention should be paid to preservation, processing, and cooking of food to avoid bacterial contamination. To prevent sickness, travelers should know the disease prevalence at their destinations in advance.

Lessons from an active surveillance pilot to assess the pneumonia of unknown etiology surveillance system in China, 2016: the need to increase clinician participation in the detection and reporting of emerging respiratory infectious diseases.

BACKGROUND: We sought to assess reporting in China's Pneumonia of Unknown Etiology (PUE) passive surveillance system for emerging respiratory infections and to identify ways to improve the PUE surveillance system's detection of respiratory infections of public health significance. METHODS: From February 29-May 29, 2016, we actively identified and enrolled patients in two hospitals with acute respiratory infections (ARI) that met all PUE case criteria. We reviewed medical records for documented exposure history associated with respiratory infectious diseases, collected throat samples that were tested for seasonal and avian influenza, and interviewed clinicians regarding reasons for reporting or not reporting PUE cases. We described and analyzed the proportion of PUE cases reported and clinician awareness of and practices related to the PUE system. RESULTS: Of 2619 ARI admissions in two hospitals, 335(13%) met the PUE case definition; none were reported. Of 311 specimens tested, 18(6%) were seasonal influenza virus-positive; none were avian influenza-positive. < 10% PUE case medical records documented whether or not there were exposures to animals or others with respiratory illness. Most commonly cited reasons for not reporting cases were no awareness of the PUE system (76%) and not understanding the case definition (53%). CONCLUSIONS: Most clinicians have limited awareness of and are not reporting to the PUE system. Exposures related to respiratory infections are rarely documented in medical records. Increasing clinicians' awareness of the PUE system and including relevant exposure items in standard medical records may increase reporting.

Epidemiology of Imported Infectious Diseases, China, 2005-2016.

Imported infectious diseases are becoming a serious public health threat in China. However, limited information concerning the epidemiologic characteristics of imported infectious diseases is available. In this study, we collected data related to imported infectious diseases in mainland China from the National Information Reporting System of Infectious Diseases and analyzed demographic, temporal, and spatial distributions. The number of types of imported infectious diseases reported increased from 2 in 2005 to 11 in 2016. A total of 31,740 cases of infectious disease were imported to mainland China during 2005-2016; most of them were found in Yunnan Province. The cases were imported mainly from Africa and Asia. As a key and effective measure, pretravel education should be strengthened for all migrant workers and tourists in China, and border screening, cross-border international cooperation, and early warning should be further improved.

Severe human infection with a novel avian-origin influenza A(H7N4) virus.

Human infections with influenza H7 subtypes, such as H7N9, have raised concerns worldwide. Here, we report a human infection with a novel influenza A(H7N4) virus. A 68 years-old woman with cardiovascular and cholecystic comorbidities developed rapidly progressed pneumonia with influenza-like-illness as initial symptom, recovered after 23 days-hospitalization including 8 days in ICU. Laboratory indicators for liver and blood coagulation dysfunction were observed. Oseltamivir phosphate, glucocorticoids and antibiotics were jointly implemented, with nasal catheterization of oxygen inhalation for this patient. We obtained the medical records and collected serial respiratory and blood specimens from her. We collected throat, cloacal and/or feces samples of poultry and wild birds from the patient's backyard, neighborhood, local live poultry markets (LPMs) and the nearest lake. All close contacts of the patient were followed up and sampled with throat swabs and sera. Influenza viruses and other respiratory pathogens were tested by real-time RT-PCR, viral culturing and/or sequencing for human respiratory and bird samples. Micro-neutralizing assay was performed for sera. A novel reassortant wild bird-origin H7N4 virus is identified from the patient and her backyard poultry (chickens and ducks) by sequencing, which is distinct from previously-reported avian H7N4 and H7N9 viruses. At least four folds increase of neutralizing antibodies to H7N4 was detected in her convalescent sera. No samples from close contacts, wild birds or other poultry were tested positive for H7N4 by real-time RT-PCR.

Clusters of Human Infection and Human-to-Human Transmission of Avian Influenza A(H7N9) Virus, 2013-2017.

To detect changes in human-to-human transmission of influenza A(H7N9) virus, we analyzed characteristics of 40 clusters of case-patients during 5 epidemics in China in 2013-2017. Similarities in number and size of clusters and proportion of clusters with probable human-to-human transmission across all epidemics suggest no change in human-to-human transmission risk.

Preliminary Epidemiology of Human Infections with Highly Pathogenic Avian Influenza A(H7N9) Virus, China, 2017.

We compared the characteristics of cases of highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI) A(H7N9) virus infections in China. HPAI A(H7N9) case-patients were more likely to have had exposure to sick and dead poultry in rural areas and were hospitalized earlier than were LPAI A(H7N9) case-patients.

Sudden increase in human infection with avian influenza A(H7N9) virus in China, September-December 2016.

Since the first outbreak of avian influenza A(H7N9) virus in humans was identified in 2013, there have been five seasonal epidemics observed in China. An earlier start and a steep increase in the number of humans infected with H7N9 virus was observed between September and December 2016, raising great public concern in domestic and international societies. The epidemiological characteristics of the recently reported confirmed H7N9 cases were analysed. The results suggested that although more cases were reported recently, most cases in the fifth epidemic were still highly sporadically distributed without any epidemiology links; the main characteristics remained unchanged and the genetic characteristics of virus strains that were isolated in this epidemic remained similar to earlier epidemics. Interventions included live poultry market closures in several cities that reported more H7N9 cases recently.

Sero-epidemiologic study of influenza A(H7N9) infection among exposed populations, China 2013-2014.

BACKGROUND: The first human infections of novel avian influenza A(H7N9) virus were identified in China in March 2013. Sentinel surveillance systems and contact tracing may not identify mild and asymptomatic human infections of influenza A(H7N9) virus. OBJECTIVES: We assessed the seroprevalence of antibodies to influenza A(H7N9) virus in three populations during the early stages of the epidemic. PATIENTS/METHODS: From March 2013 to May 2014, we collected sera from the general population, poultry workers, and contacts of confirmed infections in nine Chinese provinces reporting human A(H7N9) infections and, for contacts, second sera 2-3 weeks later. We screened for A(H7N9) antibodies by advanced hemagglutination inhibition (HI) assay and tested sera with HI titers ≥20 by modified microneutralization (MN) assay. MN titers ≥20 or fourfold increases in paired sera were considered seropositive. RESULTS: Among general population sera (n=1480), none were seropositive. Among poultry worker sera (n=1866), 28 had HI titers ≥20; two (0.11%, 95% CI: 0.02-0.44) were positive by MN. Among 61 healthcare and 117 non-healthcare contacts' sera, five had HI titers ≥20, and all were negative by MN. There was no seroconversion among 131 paired sera. CONCLUSIONS: There was no evidence of widespread transmission of influenza A(H7N9) virus during March 2013 to May 2014, although A(H7N9) may have caused rare, previously unrecognized infections among poultry workers. Although the findings suggest that there were few undetected cases of influenza A(H7N9) early in the epidemic, it is important to continue monitoring transmission as virus and epidemic evolve.

Comparison of the first three waves of avian influenza A(H7N9) virus circulation in the mainland of the People's Republic of China.

BACKGROUND: H7N9 human cases were first detected in mainland China in March 2013. Circulation of this virus has continued each year shifting to typical winter months. We compared the clinical and epidemiologic characteristics for the first three waves of virus circulation. METHODS: The first wave was defined as reported cases with onset dates between March 31-September 30, 2013, the second wave was defined as October 1, 2013-September 30, 2014 and the third wave was defined as October 1, 2014-September 30, 2015. We used simple descriptive statistics to compare characteristics of the three distinct waves of virus circulation. RESULTS: In mainland China, 134 cases, 306 cases and 219 cases were detected and reported in first three waves, respectively. The median age of cases was statistically significantly older in the first wave (61 years vs. 56 years, 56 years, p < 0.001) compared to the following two waves. Most reported cases were among men in all three waves. There was no statistically significant difference between case fatality proportions (33, 42 and 45%, respectively, p = 0.08). There were no significant statistical differences for time from illness onset to first seeking healthcare, hospitalization, lab confirmation, initiation antiviral treatment and death between the three waves. A similar percentage of cases in all waves reported exposure to poultry or live poultry markets (87%, 88%, 90%, respectively). There was no statistically significant difference in the occurrence of severe disease between the each of the first three waves of virus circulation. Twenty-one clusters were reported during these three waves (4, 11 and 6 clusters, respectively), of which, 14 were considered to be possible human-to-human transmission. CONCLUSION: Though our case investigation for the first three waves found few differences between the epidemiologic and clinical characteristics, there is continued international concern about the pandemic potential of this virus. Since the virus continues to circulate, causes more severe disease, has the ability to mutate and become transmissible from human-to-human, and there is limited natural protection from infection in communities, it is critical that surveillance systems in China and elsewhere are alert to the influenza H7N9 virus.

Assessing Change in Avian Influenza A(H7N9) Virus Infections During the Fourth Epidemic - China, September 2015-August 2016.

Since human infections with avian influenza A(H7N9) virus were first reported by the Chinese Center for Disease Control and Prevention (China CDC) in March 2013 (1), mainland China has experienced four influenza A(H7N9) virus epidemics. Prior investigations demonstrated that age and sex distribution, clinical features, and exposure history of A(H7N9) virus human infections reported during the first three epidemics were similar (2). In this report, epidemiology and virology data from the most recent, fourth epidemic (September 2015-August 2016) were compared with those from the three earlier epidemics. Whereas age and sex distribution and exposure history in the fourth epidemic were similar to those in the first three epidemics, the fourth epidemic demonstrated a greater proportion of infected persons living in rural areas, a continued spread of the virus to new areas, and a longer epidemic period. The genetic markers of mammalian adaptation and antiviral resistance remained similar across each epidemic, and viruses from the fourth epidemic remained antigenically well matched to current candidate vaccine viruses. Although there is no evidence of increased human-to-human transmissibility of A(H7N9) viruses, the continued geographic spread, identification of novel reassortant viruses, and pandemic potential of the virus underscore the importance of rigorous A(H7N9) virus surveillance and continued risk assessment in China and neighboring countries.

[Epidemiological characteristics of Middle East Respiratory Syndrome outbreak in the Republic of Korea, 2015].

OBJECTIVE: To analyze the epidemiological characteristics of Middle East Respiratory Syndrome (MERS) outbreak in the Republic of Korea in 2015 and provide related information for the public health professionals in China. METHODS: The incidence data of MERS were collected from the websites of the Korean government, WHO and authoritative media in Korea for this epidemiological analysis. RESULTS: Between May 20 and July 13, 2015, a total of 186 confirmed MERS cases (1 index case, 29 secondary cases, 125 third generation cases, 25 fourth generation cases and 6 cases without clear generation data), including 36 deaths (case fatality rate: 19%), were reported in Korea. All cases were associated with nosocomial transmission except the index case and two possible family infections. Sixteen hospitals in 11 districts in 5 provinces/municipalities in Korea reported confirmed MERS cases, involving 39 medical professionals or staff. For the confirmed cases and death cases, the median ages were 55 years and 70 years respectively, and the cases and deaths in males accounted for 60% and 67% respectively. Up to 78% of the deaths were with underlying medical conditions. Besides the index case, other 12 patients were reported to cause secondary cases, in which 1 caused 84 infections. One imported MERS case from Korea was confirmed in China on May 29, no secondary cases occurred. The viruses strains isolated from the cases in Korea and the imported case in China show no significant variation compared with the strains isolated in the Middle East. CONCLUSION: The epidemiological pattern of the MERS outbreak in Korea was similar to MERS outbreaks occurred in the Middle East.

[Development of an index system for the comprehensive evaluation on public health emergency events surveillance system in China].

OBJECTIVE: To establish a comprehensive evaluation index system for the China Public Health Emergency Events Surveillance System (CPHEESS). METHODS: A draft index system was built through literature review and under the consideration of the characteristics on CPHEESS. Delphi method was adapted to determine the final index system. RESULTS: The index system was divided into primary, secondary and tertiary levels. There were 4 primary indicators: System structure, Network platform, Surveillance implementation reports with Data analysis and utilization. There were 16 secondary and 70 tertiary indicators being set, with System structure including 14 tertiary indicators (accounted for 20.00%), 21 Network platforms (accounted for 30.00%). Twenty-four Surveillance implementation reports (accounted for 34.29%), 11 Data analysis and utilization (accounted for 15.71%). The average score of importance of each indicators was 4.29 (3.77-4.94), with an average coefficient variation as 0.14 (0.12-0.16). The mean Chronbach's α index was 0.84 (0.81-0.89). The adaptability of each related facilities indicator was specified. CONCLUSION: The primary indicators were set in accordance with the characteristics and goals of the surveillance systems. Secondary indicators provided key elements in the management and control of the system while the tertiary indicators were available and operative. The agreement rate of experts was high with good validity and reliability. This index system could be used for CPHEESS in future.

[Information obtained through Internet-based media surveillance regarding domestic public health emergencies in 2013].

OBJECTIVE: To analyze the information obtained through Internet-based media surveillance in 2013 on domestic public health emergencies and to compare with the related data reported through Chinese Public Health Emergency Management Information System (PHEMIS), and to study the role of Internet-based Media Surveillance Program (IBMSP) in the detection of public health emergencies. METHODS: A descriptive analysis was conducted based on the database of the information on domestic public health emergencies. Information was obtained through the Internet-based media surveillance in 2013. RESULTS: A total of 752 pieces of information regarding domestic public health emergencies in 31 provinces were obtained, through the IBMSP, run by the China CDC in 2013. 53.46% of all the information were categorized as initial ones on public health emergency while another 22.07% were considered as updated ones. 41.62% of the information were related to infectious diseases with another 24.73% to food poisoning. 27.53% of the information were from official websites of governments and professional organizations, with the rest 72.47% were from media. As for corresponding public health emergencies, 41.79% were food poisoning and 18.66% were infectious diseases. 22.39% of them occurred in schools, 18.16% in other organizations and 16.92% in households. 28.86% were reported through Chinese PHEMIS. For the 116 public health emergencies that both related to information obtained through Internet-based media surveillance in 2013 and reported through PHEMIS, the median days of interval between illness onset of the first case as well as reported by media, interval between onset of the first case as well as reported through PHEMIS, were 2.5 days and 2.0 days respectively. 19.83% of the emergencies were first reported by media than through PHEMIS. CONCLUSION: Internet-based media surveillance programs had become an important way to detect public health emergencies and could serve as the supplement to the classic surveillance programs on public health emergencies.

[Epidemiological characteristics of human avian influenza A (H7N9) virus infection in China].

OBJECTIVE: To investigate the epidemiological characteristics of human infections with avian influenza A (H7N9) in China and to provide scientific evidence for the adjustment of preventive strategy and control measures. METHODS: Demographic and epidemiologic information on human cases were collected from both reported data of field epidemiological investigation and the reporting system for infectious diseases. RESULTS: A total of 433 cases including 163 deaths were reported in mainland China before June 4, 2014. Two obvious epidemic peaks were noticed, in March to April, 2013 and January to February, 2014. Confirmed cases emerged in 14 areas of China. Five provinces, including Zhejiang, Guangdong, Jiangsu, Shanghai, and Hunan, reported about 85% of the total cases. Median age of the confirmed cases was 58 years (range, 1-91), with 70% as males. Of the 418 cases with available data, 87% had ever exposed to live poultry or contaminated environments. 14 clusters were identified but human to human transmission could not be ruled out in 9 clusters. CONCLUSION: Human infections with avian influenza A (H7N9) virus showed the characteristics of obvious seasonal distribution, with certain regional clusters. The majority of confirmed cases were among the elderly, with more males seen than the females. Data showed that main source of infection was live poultry and the live poultry market had played a significant role in the transmission of the virus.

[A discussion on the strategy of evaluating the communicable disease surveillance systems in US Center for Disease Control and Prevention and World Health Organization].

OBJECTIVE: To compare the different surveillance system evaluation guidelines proposed by US Center for Disease Control and Prevention (CDC) and WHO, so as to develop an evaluation strategy suitable for communicable disease surveillance systems in China. METHODS: Systematic collection and review on the guidelines that were proposed by US CDC and WHO. Situation analysis together with feasibility analysis were linked to the analysis of evaluation strategy used in China. RESULTS: US CDC guidelines were more appropriate for evaluating those single or simple systems that focusing on those 'system characteristics' while the. WHO protocols were more appropriate for evaluating the multi-system or complicated system which focusing on data related to 'system functions'. The US CDC guidelines had been widely used in China and it was the right moment to start to evaluate the functions. CONCLUSION: More flexible and comprehensive strategy based on national conditions is needed when constitute the national communicable disease surveillance evaluation guidelines. The multi-step strategy described in this article could be used as reference.

[Study on the timeliness of detection and reporting on public health emergency events in China].

OBJECTIVE: To analyze the timeliness of detection and reporting on public health emergency events, and to explore the effective strategies for improving the relative capacity on those issues. METHODS: We conducted a retrospective survey on 3275 emergency events reported through Public Health Emergency Events Surveillance System from 2005 to the first half of 2006. Developed by county Centers for Disease Control and Prevention, a uniformed self-administrated questionnaire was used to collect data, which would include information on the detection, reporting of the events. RESULTS: For communicable diseases events, the median of time interval between the occurrence of first case and the detection of event was 6 days (P25 = 2, P75 = 13). For food poisoning events and clusters of disease with unknown origin, the medians were 3 hours (P25, P75 = 16) and 1 days (P25 = 0, P75 = 5). 71.54% of the events were reported by the discoverers within 2 hours after the detection. CONCLUSION: In general, the ranges of time intervals between the occurrence, detection or reporting of the events were different, according to the categories of events. The timeliness of detection and reporting of events could have been improved dramatically if the definition of events, according to their characteristics, had been more reasonable and accessible, as well as the improvement of training program for healthcare staff and teachers.