Influence of meteorological factors and air pollution on the outbreak of severe acute respiratory syndrome

OBJECTIVES: To understand the association between the outbreak of severe acute respiratory syndrome (SARS) and meteorological factors and air pollution. STUDY DESIGN: An ecological study was conducted. METHODS: Three hundred and fifty primary probable SARS cases diagnosed in mainland China between 1 January and 31 May 2003, and their 6727 close contacts during the period of their clinical symptoms before admission, were included in this study. Of the 6727 close contacts, 135 (2.0%) later developed clinical symptoms and were diagnosed as probable SARS cases. The daily meteorological data and daily air pollution data during the same SARS outbreak period in mainland China were used in the data analysis. Logistic regression analyses were conducted to explore the association between the secondary attack rate of SARS and meteorological factors and air pollution. RESULTS: In univariate analyses, daily average temperature (DAT), daily average air pressure (DAAP), and daily average relative humidity (DARH) were inversely associated with secondary attack rate (P<0.001); a significant positive association was found for daily hours of sunshine (DHS) (P<0.001). In multivariate analyses, factors associated with secondary attack rate were DAAP (odds ratio (OR)=0.53, 95% confidence interval (CI): 0.42, 0.66), DARH (OR=0.73, 95% CI: 0.53, 1.00), and daily average wind velocity (DAWV; OR=0.81, 95% CI: 0.68, 0.96). Adjustment for the onset time of a primary case led to little change in the results. In addition, in Hebei Province, a major affected area in China, only DAWV (OR=0.38, 95% CI: 0.20, 0.72) was a significant predictor of secondary attack rate with adjustment for the onset time of primary case. In Inner Mongolia, another major affected area in China, DAWV (OR=0.50, 95% CI: 0.26, 0.94) and DHS (OR=0.27, 95% CI: 0.09, 0.81) were significant predictors of secondary attack rate with adjustment for the onset time of primary case. CONCLUSIONS: Our results suggest that the SARS outbreak was significantly associated with DAWV, and that DAAP, DARH and DHS may also have influenced the SARS outbreak to some extent. However, because of ecological fallacy and uncontrolled confounding effects that may have biased the results, the association between the SARS outbreak and these meteorological factors and air pollution deserve further investigation.     

Severe acute respiratory syndrome, Beijing, 2003

The largest outbreak of severe acute respiratory syndrome (SARS) struck Beijing in spring 2003. Multiple importations of SARS to Beijing initiated transmission in several healthcare facilities. Beijing's outbreak began March 5; by late April, daily hospital admissions for SARS exceeded 100 for several days; 2,521 cases of probable SARS occurred. Attack rates were highest in those 20-39 years of age; 1% of cases occurred in children <10 years. The case-fatality rate was highest among patients >65 years (27.7% vs. 4.8% for those 20-64 years, p < 0.001). Healthcare workers accounted for 16% of probable cases. The proportion of case-patients without known contact to a SARS patient increased significantly in May. Implementation of early detection, isolation, contact tracing, quarantine, triage of case-patients to designated SARS hospitals, and community mobilization ended the outbreak.     

SARS outbreak, Taiwan, 2003

We studied the severe acute respiratory syndrome (SARS) outbreak in Taiwan, using the daily case-reporting data from May 5 to June 4 to learn how it had spread so rapidly. Our results indicate that most SARS-infected persons had symptoms and were admitted before their infections were reclassified as probable cases. This finding could indicate efficient admission, slow reclassification process, or both. The high percentage of nosocomial infections in Taiwan suggests that infection from hospitalized patients with suspected, but not yet classified, cases is a major factor in the spread of disease. Delays in reclassification also contributed to the problem. Because accurate diagnostic testing for SARS is currently lacking, intervention measures aimed at more efficient diagnosis, isolation of suspected SARS patients, and reclassification procedures could greatly reduce the number of infections in future outbreaks.     

Management of inpatients exposed to an outbreak of severe acute respiratory syndrome (SARS)

This is a prospective observational study of a cohort of inpatients exposed to a severe acute respiratory syndrome (SARS) outbreak. Strict infection control policies were instituted. The 70 patients exposed to the SARS outbreak were isolated from the rest of the hospital. They were triaged, quarantined and cohorted in three open plan wards. Selective isolation was carried out immediately when symptoms and signs suspicious of SARS manifested clinically. The patients' ages ranged from 21 to 90 years and 56% had surgery before the quarantine. Sixteen patients with unexplained fever during the period of quarantine were isolated, seven of whom were eventually diagnosed with probable SARS. The crude incidence of SARS in our cohort was 10%. The SARS case fatality was 14%. No secondary transmission of the SARS virus within the cohort was observed. Strict infection control, together with appropriate triaging, cohorting and selective isolation, is an effective and practical model of intervention in cohorts exposed to a SARS outbreak. Such a management strategy eases the logistic constraints imposed by demands for large numbers of isolation facilities in the face of a massive outbreak.     

Two Linked Enteroinvasive Escherichia coli Outbreaks,Nottingham, UK,June 2014

Enteroinvasive Escherichia coli (EIEC) outbreaks are uncommon in Europe. In June 2014, two EIEC outbreaks occurred in Nottingham, UK, within 2 days; outbreak A was linked to a takeaway restaurant and outbreak B to a wedding party. We conducted 2 analytical studies: a case–control study for outbreak A and a cohort study for outbreak B. We tested microbiological and environmental samples, including by using whole-genome sequencing. For both outbreaks combined, we identified 157 probable case-patients; 27 were laboratory-confirmed as EIEC O96:H19–positive. Combined epidemiologic, microbiological, and environmental findings implicated lettuce as the vehicle of infection in outbreak A, but the source of the organism remained unknown. Whole-genome sequencing identified the same organism in cases from both outbreaks, but no epidemiologic link was confirmed. These outbreaks highlight that EIEC has the capacity to cause large and severe gastrointestinal disease outbreaks and should be considered as a potential pathogen in foodborne outbreaks in Europe.     

四川省首起家庭内暴发传染性非典型肺炎调查

目的 对四川省首起可疑传染性非典型肺炎(SARS)的家庭暴发病例进行流行病学调查，病原学、血清学检测，明确诊断。方法 对发生于2003年2月12日的首起家庭暴发病例进行流行病学调查，病原学和血清学检测。结果该起暴发发生于四川省广元市某厂，1家3口皆发病，有密切接触史，符合传染性非典型肺炎的临床诊断标准。患者鼻和咽拭子，上呼吸道分泌物标本，均未分离到流感病毒，禽流感病毒和肺炎衣原体。患者A恢复期血冠状病毒IgM和IgG抗体阳性，患者B恢复期血冠状病毒IgG抗体阳性，患者C急性期血冠状病毒和肺炎衣原体IgM抗体阳性。结论 该起暴发的流行病学、临床特征、血清学等均符合传染性非典型肺炎的诊断。为四川省首起传染性非典型肺炎疫情。     

Foundations of the severe acute respiratory syndrome preparedness and response plan for healthcare facilities.

OBJECTIVE: To help facilities prepare for potential future cases of severe acute respiratory syndrome (SARS). DESIGN AND PARTICIPANTS: The Centers for Disease Control and Prevention (CDC), assisted by members of professional societies representing public health, healthcare workers, and healthcare administrators, developed guidance to help facilities both prepare for and respond to cases of SARS. INTERVENTIONS: The recommendations in the CDC document were based on some of the important lessons learned in healthcare settings around the world during the SARS outbreak of 2003, including that (1) a SARS outbreak requires a coordinated and dynamic response by multiple groups; (2) unrecognized cases of SARS-associated coronavirus are a significant source of transmission; (3) restricting access to the healthcare facility can minimize transmission; (4) airborne infection isolation is recommended, but facilities and equipment may not be available; and (5) staffing needs and support will pose a significant challenge. CONCLUSIONS: Healthcare facilities were at the center of the SARS outbreak of 2003 and played a key role in controlling the epidemic. Recommendations in the CDC's SARS preparedness and response guidance for healthcare facilities will help facilities prepare for possible future outbreaks of SARS.     

The SARS outbreak in a general hospital in Tianjin, China -- the case of super-spreader

Severe acute respiratory syndrome (SARS) is a newly emerged infectious disease with a high case-fatality rate and devastating socio-economic impact. In this report we summarized the results from an epidemiological investigation of a SARS outbreak in a hospital in Tianjin, between April and May 2003. We collected epidemiological and clinical data on 111 suspect and probable cases of SARS associated with the outbreak. Transmission chain and outbreak clusters were investigated. The outbreak was single sourced and had eight clusters. All SARS cases in the hospital were traced to a single patient who directly infected 33 people. The patients ranged from 16 to 82 years of age (mean age 38.5 years); 38.7% were men. The overall case fatality in the SARS outbreak was 11.7% (13/111). The outbreak lasted around 4 weeks after the index case was identified. SARS is a highly contagious condition associated with substantial case fatality; an outbreak can result from one patient in a relatively short period. However, stringent public health measures seemed to be effective in breaking the disease transmission chain.     

A role of high impact weather events in waterborne disease outbreaks in Canada, 1975 - 2001

Recent outbreaks of Escherichia coli O157:H7, Campylobacter, and Cryptosporidium have heightened awareness of risks associated with contaminated water supply. The objectives of this research were to describe the incidence and distribution of waterborne disease outbreaks in Canada in relation to preceding weather conditions and to test the association between high impact weather events and waterborne disease outbreaks. We examined extreme rainfall and spring snowmelt in association with 92 Canadian waterborne disease outbreaks between 1975 and 2001, using case-crossover methodology. Explanatory variables including accumulated rainfall, air temperature, and peak stream flow were used to determine the relationship between high impact weather events and the occurrence of waterborne disease outbreaks. Total maximum degree-days above 0 degrees C and accumulated rainfall percentile were associated with outbreak risk. For each degree-day above 0 degrees C the relative odds of an outbreak increased by a factor of 1.007 (95% confidence interval [CI] = 1.002 - 1.012). Accumulated rainfall percentile was dichotomized at the 93rd percentile. For rainfall events greater than the 93rd percentile the relative odds of an outbreak increased by a factor of 2.283 (95% [CI] = 1.216 - 4.285). These results suggest that warmer temperatures and extreme rainfall are contributing factors to waterborne disease outbreaks in Canada. This could have implications for water management and public health initiatives.     

Predicting case numbers during infectious disease outbreaks when some cases are undiagnosed

We describe a method for calculating 95 per cent bounds for the current number of hidden cases and the future number of diagnosed cases during an outbreak of an infectious disease. A Bayesian Markov chain Monte Carlo approach is used to fit a model of infectious disease transmission that takes account of undiagnosed cases. Assessing this method on simulated data, we find that it provides conservative 95 per cent bounds for the number of undiagnosed cases and future case numbers, and that these bounds are robust to modifications in the assumptions generating the simulated data. Moreover, the method provides a good estimate of the initial reproduction number, and the reproduction number in the latter stages of the outbreak. Applying the approach to SARS data from Hong Kong, Singapore, Taiwan and Canada, the bounds on future diagnosed cases are found to be reliable, and the bounds on hidden cases suggests that there were few hidden cases remaining at the end of the outbreaks in each region. We estimate that the initial reproduction numbers lay between 1.5 and 3, and the reproduction numbers in the later stages of the outbreak lay between 0.36 and 0.6.     

Environmental indicators for human norovirus outbreaks

Norovirus is the most common cause of outbreaks of non-bacterial gastroenteritis in human. While the winter seasonality of norovirus outbreaks has been widely reported, the association between norovirus outbreak epidemics and environmental factors remains not fully understood. This literature review is intended to improve understanding of environmental factors governing norovirus outbreaks and how the factors affect norovirus transmission. To that end, a large number of studies (67) from countries around the world were critically reviewed and discussed. Results of the literature review show that temperature, humidity, and rainfall are the most important environmental variables governing the norovirus epidemic cycle. It was found that low temperature between ?6.6 and 20 °C, relative humidity between 10 and 66 %, and rainfall from 1 day to 3 months before an outbreak are effective ranges of the environmental factors, which favor the prevalence of norovirus. Some other environmental factors might have an association with the cycle of norovirus epidemics. However, further investigations are needed to understand effects of the other factors on norovirus incidence. The findings of this literature review improve our understanding of the relationship between norovirus outbreaks and environmental factors and provide the direction for future research on norovirus outbreaks.     

Public health management of an outbreak of group C meningococcal disease in university campus residents.

BACKGROUND: Increasing numbers of outbreaks of Group C meningococcal disease in teenagers and young adults led to a new policy in the UK in 1999 of vaccinating all new college students. The largest of these outbreaks involved seven students in one university, six of whom were from one hall of residence, and two of whom died. METHODS: Control of the outbreak involved close medical surveillance of resident students, mass chemoprophylaxis and vaccination, and wide dissemination of daily information bulletins. Investigation of the epidemiology of the outbreak involved searching for the network of close contacts between cases, a prevalence survey of carriage of meningogocci and a case control study of risk factors for carriage. RESULTS: Clinical cases could be linked by a discrete network of social contacts within the halls of residence, but the Group C epidemic strain (2a P1.5) was not detected in 454 students (upper 95% confidence interval 0.7%). Carriage of any meningococcal strain (19%) was associated with patronage of the campus bar (OR = 3.0, 0.99-9.1). CONCLUSION: Important factors in the control of the outbreak were rapid institution of mass chemopropylaxis and immunisation of residents, and involvement of student organizations in the dissemination of information about the disease and its control. The role of campus bars in dissemination of the carriage of meningogocci deserves further investigation.     

Different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures

Severe acute respiratory syndrome (SARS) has been the first severe contagious disease to emerge in the 21st century. The available epidemic curves for SARS show marked differences between the affected regions with respect to the total number of cases and epidemic duration, even for those regions in which outbreaks started almost simultaneously and similar control measures were implemented at the same time. The authors developed a likelihood-based estimation procedure that infers the temporal pattern of effective reproduction numbers from an observed epidemic curve. Precise estimates for the effective reproduction numbers were obtained by applying this estimation procedure to available data for SARS outbreaks that occurred in Hong Kong, Vietnam, Singapore, and Canada in 2003. The effective reproduction numbers revealed that epidemics in the various affected regions were characterized by markedly similar disease transmission potentials and similar levels of effectiveness of control measures. In controlling SARS outbreaks, timely alerts have been essential: Delaying the institution of control measures by 1 week would have nearly tripled the epidemic size and would have increased the expected epidemic duration by 4 weeks.     

Outbreak of food poisoning due to Salmonella typhimurium DT4 in mayonnaise.

In July 1989 a large outbreak of food poisoning (68 cases) occurred at a private club in Teddington (London Borough of Richmond-upon-Thames). Initial enquiries indicated that the peak of the outbreak occurred between 20th and 26th July. An epidemiological investigation (using self-completed questionnaires) was set up to determine the probable source of infection. Two groups among those exposed were selected: club staff (129), and cricket teams playing in a club tournament (105). Response rates were 89% and 64% respectively. Overall 50% (89) had gastrointestinal symptoms, including two hospital admissions. A highly significant association was found between illness and eating sandwiches containing mayonnaise. Microbiological investigations found Salmonella typhimurium DT4 in 36 of 68 faecal samples taken. This organism is not usually associated with food poisoning outbreaks. The probable source was identified as a flock of one of the egg suppliers.     

The 2003 SARS outbreak and its impact on infection control practices

Severe Acute Respiratory Syndrome (SARS) emerged recently as a new infectious disease that was transmitted efficiently in the healthcare setting and particularly affected healthcare workers (HCWs), patients and visitors. The efficiency of transmission within healthcare facilities was recognised following significant hospital outbreaks of SARS in Canada, China, Hong Kong, Singapore, Taiwan and Vietnam. The causative agent of SARS was identified as a novel coronavirus, the SARS coronavirus. This was largely spread by direct or indirect contact with large respiratory droplets, although airborne transmission has also been reported. High infection rates among HCWs led initially to the theory that SARS was highly contagious and the concept of 'super-spreading events'. Such events illustrated that lack of infection control (IC) measures or failure to comply with IC precautions could lead to large-scale hospital outbreaks. SARS was eventually contained by the stringent application of IC measures that limited exposure of HCWs to potentially infectious individuals. As the 'global village' becomes smaller and other microbial threats to health emerge, or re-emerge, there is an urgent need to develop a global strategy for infection control in hospitals. This paper provides an overview of the main IC practices employed during the 2003 SARS outbreak, including management measures, dedicated SARS hospitals, personal protective equipment, isolation, handwashing, environmental decontamination, education and training. The psychological and psychosocial impact on HCWs during the outbreak are also discussed. Requirements for IC programmes in the post-SARS period are proposed based on the major lessons learnt from the SARS outbreak.     

浦东新区幼托机构聚集性手足口病流行情况及影响因素研究

探讨浦东新区幼托机构聚集性手足口病事件与室内环境、气象等因素之间的关系,为托幼机构手足口病聚集性事件的防控提供科学依据.方法 应用方差分析、Pearson相关分析及多元线性回归模型对浦东新区涉及报告聚集性事件幼托机构91个班级室内环境因素及气象因素与手足口病事件关系进行研究,应用贝叶斯模型和克里格差值法对该类事件时空分布特征进行分析.结果 室内紫外线照度可能为聚集性手足口病事件保护因素,室内温度较高可能是危险因素;室外周平均风速和气压与该类事件呈负相关,周相对平均湿度和平均最低气温与事件数呈正相关(P值均<0.05);室内紫外线照度和温度纳入环境模型,对托幼机构手足口病病例罹患率影响的回归系数分别为-0.004和0.02;平均风速、气压和最低温度纳入气象模型,对托幼机构手足口病病例罹患率影响的回归系数分别为-11.68,-9.37,-6.45.结论室内环境因素及气象因素与聚集性手足口病事件有密切的关系,同时区域特征与其发生也有一定关系.应结合以上各因素开展及时、高效的防控措施.     

The economic impact of SARS: how does the reality match the predictions?

OBJECTIVES: To perform a retrospective analysis of the macro-economic impact of the 2003 Severe Acute Respiratory Syndrome (SARS) outbreak. METHODS: As several years have now passed, it is possible to interrogate national statistics that have become available since the outbreak to provide a more accurate estimate of the actual macro-economic impact of SARS. National statistics were examined for anomalies that corresponded to the timing of the SARS outbreak and, where possible, the size of any gain or loss found estimated. RESULTS: Estimates and models produced at the time of the outbreak suggested that SARS could have a catastrophic effect on the global economy. Our analysis suggests that the scale of the SARS impact on affected economies was far smaller than suggested by contemporary media reports and model estimates. CONCLUSIONS: This exercise holds important lessons for estimating the economic impact of future outbreaks - such as pandemic influenza - and measures to control or prevent them. We suggest that further work is needed to develop a more comprehensive macro-economic model able to more accurately estimate the relative cost and effect of a global response to outbreaks of international concern. The implications of our findings are discussed in the light of a prospective influenza pandemic.     

Update: outbreak of severe acute respiratory syndrome--worldwide, 2003

CDC and the World Health Qrganization (WHO) are continuing to investigate the multicountry outbreak of unexplained atypical pneumonia referred to as severe acute respiratory syndrome (SARS). Pending development of confirmatory laboratory testing capacity, CDC's interim suspected SARS case definition is based on clinical criteria and epidemiologic linkage to other SARS cases or areas with community transmission of SARS. This case definition will be updated periodically as new information becomes available. Epidemiologic and laboratory investigations of SARS are ongoing. As of April 2, 2003, a total of 2,223 suspected and/or probable SARS cases have been reported to WHO from 16 countries, including the United States. The reported SARS cases include 78 deaths (case-fatality proportion: 3.5%). This report summarizes SARS cases among U.S. residents and surveillance and prevention activities in the United States.     

"Exposing the cracks": Severe Acute Respiratory Syndrome and the Hong Kong health system

PURPOSE: Hong Kong was particularly affected by the 2003 outbreak of Severe Acute Respiratory Syndrome (SARS). During the epidemic, it seemed as if the Hong Kong government and health system were barely coping, leading to calls of mismanagement and governance incapacity. In the wake of the SARS outbreak, two inquiries were conducted. The purpose of this article is to review the Hong Kong's response to SARS from the perspective of two inquiries. DESIGN/METHODOLOGY/APPROACH: An historical analysis of the institutional arrangements for health care delivery in Hong Kong is undertaken, followed by a chronology of developments in the SARS outbreak. The article then reviews outbreak management and the findings of the two inquiries. Finally, it considers whether the Hong Kong health system can be reformed to manage any future infectious disease epidemic better. FINDINGS: Both leadership and coherency were lacking in Hong Kong's response to SARS. These are age-old problems in the Hong Kong health sector. The prospects for mending the health system appear limited, given that leadership and coherency have been consistently absent features of post-1997 governance in Hong Kong. RESEARCH LIMITATIONS/IMPLICATIONS: This article reviews events in the immediate period following the SARS outbreak. A future follow-up study of the Hong Kong government and health system's capacity to respond to infectious disease outbreaks would be useful. PRACTICAL IMPLICATIONS: This article provides a review that will be useful to policymakers and researchers. ORIGINALITY/VALUE: No other article reviews the Hong Kong health system's SARS response.