Syndromic surveillance: the case for skillful investment

Utility of syndromic surveillance for the surveillance of healthcare-associated infections in resource-limited settings: a narrative review

Globally, Healthcare-associated infections (HCAIs) pose a significant threat to patient safety and healthcare systems. In low- and middle-income countries (LMICs), the lack of adequate resources to manage HCAIs, as well as the weak healthcare system, further exacerbate the burden of these infections. Traditional surveillance methods that rely on laboratory tests are cost-intensive and impractical in these settings, leading to ineffective monitoring and delayed management of HCAIs. The rates of HCAIs in resource-limited settings have not been well established for most LMICs, despite their negative consequences. This is partly due to costs associated with surveillance systems. Syndromic surveillance, a part of active surveillance, focuses on clinical observations and symptoms rather than laboratory confirmation for HCAI detection. Its cost-effectiveness and efficiency make it a beneficial approach for monitoring HCAIs in LMICs. It provides for early warning capabilities, enabling timely identification and response to potential HCAI outbreaks. Syndromic surveillance is highly sensitive and this helps balance the challenge of low sensitivity of laboratory-based surveillance systems. If syndromic surveillance is used hand-in-hand with laboratory-based surveillance systems, it will greatly contribute to establishing the true burden of HAIs in resource-limited settings. Additionally, its flexibility allows for adaptation to different healthcare settings and integration into existing health information systems, facilitating data-driven decision-making and resource allocation. Such a system would augment the event-based surveillance system that is based on alerts and rumours for early detection of events of outbreak potential. If well streamlined and targeted, to monitor priority HCAIs such as surgical site infections, hospital-acquired pneumonia, diarrheal illnesses, the cost and burden of the effects from these infections could be reduced. This approach would offer early detection capabilities and could be expanded into nationwide HCAI surveillance networks with standardised data collection, healthcare worker training, real-time reporting mechanisms, stakeholder collaboration, and continuous monitoring and evaluation. Syndromic surveillance offers a promising strategy for combating HCAIs in LMICs. It provides early warning capabilities, conserves resources, and enhances patient safety. Effective implementation depends on strategic interventions, stakeholder collaboration, and ongoing monitoring and evaluation to ensure sustained effectiveness in HCAI detection and response.

Nurses' and Medical Officers' Knowledge, Attitude, and Preparedness Toward Potential Bioterrorism Attacks

Terrorist attacks are increasingly becoming more lethal and less discriminate. The threat of bioterrorism is increasing daily. The ease of production and the broad availability of biological agents and technical know-how have led to a further spread of biological weapons and an increased desire among nations as well as terrorists to have them. Health professionals in emergency departments are expected to play crucial roles in the management of victims of bioterrorism when bioterrorism occurs. This study explored the knowledge, attitudes, and preparedness of emergency department nurses and medical officers (MOs) toward potential bioterrorist attacks in Ghana. This qualitative study utilized focus group discussions and semistructured interviews to explore the knowledge, attitudes, and preparedness of emergency department nurses and MOs toward potential bioterrorist attacks in Ghana. Data were subjected to a qualitative content analysis in which three main thematic categories were developed. These thematic categories are as follows: (a) differences in bioterrorism knowledge between emergency department nurses and emergency department MOs, (b) unprepared emergency department nurses and MOs for care during bioterrorism attacks, and (c) positive attitudes of emergency department nurses and MOs toward bioterrorism preparedness. Although emergency MOs had better knowledge of bioterrorism than their nursing counterparts, both groups of health professionals were unprepared to respond to any form of bioterrorism. Both nurses and MOs indicated the need for staff education and infrastructure readiness to be able to respond effectively to a bioterrorist attack. A well-prepared emergency department and health professionals against bioterrorism could prevent high casualty rates in a bioterrorist attack and also serve a dual purpose of dealing with other natural disasters when they occur.

Global Research on Syndromic Surveillance from 1993 to 2017: Bibliometric Analysis and Visualization

Syndromic Surveillance aims at analyzing medical data to detect clusters of illness or forecast disease outbreaks. Although the research in this field is flourishing in terms of publications, an insight of the global research output has been overlooked. This paper aims at analyzing the global scientific output of the research from 1993 to 2017. To this end, the paper uses bibliometric analysis and visualization to achieve its goal. Particularly, a data processing framework was proposed based on citation datasets collected from Scopus and Clarivate Analytics’ Web of Science Core Collection (WoSCC). The bibliometric method and Citespace were used to analyze the institutions, countries, and research areas as well as the current hotspots and trends. The preprocessed dataset includes 14,680 citation records. The analysis uncovered USA, England, Canada, France and Australia as the top five most productive countries publishing about Syndromic Surveillance. On the other hand, at the Pinnacle of academic institutions are the US Centers for Disease Control and Prevention (CDC). The reference co-citation analysis uncovered the common research venues and further analysis of the keyword cooccurrence revealed the most trending topics. The findings of this research will help in enriching the field with a comprehensive view of the status and future trends of the research on Syndromic Surveillance.

The Impact of Law on Syndromic Disease Surveillance Implementation

CONTEXT

Legal environments influence how health information technologies are implemented in public health practice settings. Syndromic disease surveillance (SyS) is a relatively new approach to surveillance that depends heavily on health information technologies to achieve rapid awareness of disease trends. Evidence suggests that legal concerns have impeded the optimization of SyS.

OBJECTIVES

To (1) understand the legal environments in which SyS is implemented, (2) determine the perceived legal basis for SyS, and (3) identify perceived legal barriers and facilitators to SyS implementation.

DESIGN

Multisite case study in which 35 key informant interviews and 5 focus groups were conducted with 75 SyS stakeholders. Interviews and focus groups were audio recorded, transcribed, and analyzed by 3 coders using thematic content analysis. Legal documents were reviewed.

SETTING

Seven jurisdictions (5 states, 1 county, and 1 city) that were purposively selected on the basis of SyS capacity and legal environment.

PARTICIPANTS

Health department directors, SyS system administrators, legal counsel, and hospital personnel.

RESULTS

Federal (eg, HIPAA) and state (eg, notifiable disease reporting) laws that authorize traditional public health surveillance were perceived as providing a legal basis for SyS. Financial incentives for hospitals to satisfy Meaningful Use regulations have eased concerns about the legality of SyS and increased the number of hospitals reporting SyS data. Legal issues were perceived as barriers to BioSense 2.0 (the federal SyS program) participation but were surmountable.

CONCLUSION

Major legal reforms are not needed to promote more widespread use of SyS. The current legal environment is perceived by health department and hospital officials as providing a firm basis for SyS practice. This is a shift from how law was perceived when SyS adoption began and has policy implications because it indicates that major legal reforms are not needed to promote more widespread use of the technology. Beyond SyS, our study suggests that federal monetary incentives can ameliorate legal concerns regarding novel health information technologies.

Limits of use of social media for monitoring biosecurity events

Compared to applications that trigger massive information streams, like earthquakes and human disease epidemics, the data input for agricultural and environmental biosecurity events (ie. the introduction of unwanted exotic pests and pathogens), is expected to be sparse and less frequent. To investigate if Twitter data can be useful for the detection and monitoring of biosecurity events, we adopted a three-step process. First, we confirmed that sightings of two migratory species, the Bogong moth (Agrotis infusa) and the Common Koel (Eudynamys scolopaceus) are reported on Twitter. Second, we developed search queries to extract the relevant tweets for these species. The queries were based on either the taxonomic name, common name or keywords that are frequently used to describe the species (symptomatic or syndromic). Third, we validated the results using ground truth data. Our results indicate that the common name queries provided a reasonable number of tweets that were related to the ground truth data. The taxonomic query resulted in too small datasets, while the symptomatic queries resulted in large datasets, but with highly variable signal-to-noise ratios. No clear relationship was observed between the tweets from the symptomatic queries and the ground truth data. Comparing the results for the two species showed that the level of familiarity with the species plays a major role. The more familiar the species, the more stable and reliable the Twitter data. This clearly presents a problem for using social media to detect the arrival of an exotic organism of biosecurity concern for which public is unfamiliar.

Emergency department and 'Google flu trends' data as syndromic surveillance indicators for seasonal influenza

We evaluated syndromic indicators of influenza disease activity developed using emergency department (ED) data - total ED visits attributed to influenza-like illness (ILI) ('ED ILI volume') and percentage of visits attributed to ILI ('ED ILI percent') - and Google flu trends (GFT) data (ILI cases/100 000 physician visits). Congruity and correlation among these indicators and between these indicators and weekly count of laboratory-confirmed influenza in Manitoba was assessed graphically using linear regression models. Both ED and GFT data performed well as syndromic indicators of influenza activity, and were highly correlated with each other in real time. The strongest correlations between virological data and ED ILI volume and ED ILI percent, respectively, were 0·77 and 0·71. The strongest correlation of GFT was 0·74. Seasonal influenza activity may be effectively monitored using ED and GFT data.

Syndromic surveillance for influenza in the emergency department-A systematic review

The science of surveillance is rapidly evolving due to changes in public health information and preparedness as national security issues, new information technologies and health reform. As the Emergency Department has become a much more utilized venue for acute care, it has also become a more attractive data source for disease surveillance. In recent years, influenza surveillance from the Emergency Department has increased in scope and breadth and has resulted in innovative and increasingly accepted methods of surveillance for influenza and influenza-like-illness (ILI). We undertook a systematic review of published Emergency Department-based influenza and ILI syndromic surveillance systems. A PubMed search using the keywords "syndromic", "surveillance", "influenza" and "emergency" was performed. Manuscripts were included in the analysis if they described (1) data from an Emergency Department (2) surveillance of influenza or ILI and (3) syndromic or clinical data. Meeting abstracts were excluded. The references of included manuscripts were examined for additional studies. A total of 38 manuscripts met the inclusion criteria, describing 24 discrete syndromic surveillance systems. Emergency Department-based influenza syndromic surveillance has been described worldwide. A wide variety of clinical data was used for surveillance, including chief complaint/presentation, preliminary or discharge diagnosis, free text analysis of the entire medical record, Google flu trends, calls to teletriage and help lines, ambulance dispatch calls, case reports of H1N1 in the media, markers of ED crowding, admission and Left Without Being Seen rates. Syndromes used to capture influenza rates were nearly always related to ILI (i.e. fever +/- a respiratory or constitutional complaint), however, other syndromes used for surveillance included fever alone, "respiratory complaint" and seizure. Two very large surveillance networks, the North American DiSTRIBuTE network and the European Triple S system have collected large-scale Emergency Department-based influenza and ILI syndromic surveillance data. Syndromic surveillance for influenza and ILI from the Emergency Department is becoming more prevalent as a measure of yearly influenza outbreaks.

Health Information in the Background: Justifying Public Health Surveillance Without Patient Consent

Often we think of collecting, storing, and using health data without patient consent as unethical and illegal. However, there are situations where the collection of health information without consent is not only ethical and legal, it is essential for community and public health. Public health surveillance – the ongoing, systematic collection, analysis, and interpretation of health-related data with the a priori purpose of preventing or controlling disease or injury, or identifying unusual events of public health importance, followed by the dissemination and use of information for public health action – allows the government to meet its ethical obligation to protect the health of the population. By adhering to public health ethics principles, public health surveillance systems, including pervasive information and computing technology (PICT), can be designed and implemented in ways that both honor individuals and protect communities.

[Syndromic surveillance: review and prospect of a promising concept]

Syndromic surveillance appeared in the field of public health surveillance in the late 90's. Initially proposed for public health identification of bioterrorism events, the method failed to provide convincing evidence of its usefulness and potential benefits. The definition which is proposed today by the Centers for Disease Control and Prevention (CDC) of Atlanta is the most commonly accepted. It defines syndromic surveillance as an automatic process that goes from registration to transfer of data recorded within the framework of a professional rather than public health goal. Systems operating today have integrated a public health approach through routine surveillance procedures with a broader focus than bioterrorism, implying active participation of the official public health surveillance structures. Syndromic surveillance offers several advantages including quick access to a large volume of data in real time, no extra-work for data registration and construction of a historical dataset useful as an historical baseline. Nevertheless, the limitations of this type of surveillance should not be forgotten (sometimes limited sensitivity, specificity, important technical burden…). Today, recorded experience shows that there is no opposition between syndromic surveillance and classical surveillance. On the contrary, they should be presented as complementary procedures. Syndromic surveillance should be analyzed from a temporal perspective, examining its short-term use as an alert mechanism, mid-term use for constitution of historical time series, and long-term use for a description of human health in the 21st century.

Monitoring data quality in syndromic surveillance: learnings from a resource limited setting

Background:

India is in the process of integrating all disease surveillance systems with the support of a World Bank funded program called the Integrated Disease Surveillance System. In this context the objective of the study was to evaluate the components of the Orissa Multi Disease Surveillance System.

Materials and Methods:

Multistage sampling was carried out, starting with four districts, followed by sequentially sampling two blocks; and in each block, two sectors and two health sub-centers were selected, all based on the best and worst performances. Two study instruments were developed for data validation, for assessing the components of the surveillance and diagnostic algorithm. The Organizational Ethics Group reviewed and approved the study.

Results:

In all 178 study subjects participated in the survey. The case definition of suspected meningitis in disease surveillance was found to be difficult, with only 29.94%, who could be correctly identified. Syndromic diagnosis following the diagnostic algorithm was difficult for suspected malaria (28.1%), ‘unusual syndrome’ (28.1%), and simple diarrhea (62%). Only 17% could correctly answer questions on follow-up cases, but only 50% prioritized diseases. Our study showed that 54% cross-checked the data before compilation. Many (22%) faltered on timeliness even during emergencies. The constraints identified were logistics (56%) and telecommunication (41%). The reason for participation in surveillance was job responsibility (34.83%).

Conclusions:

Most of the deficiencies arose from human errors when carrying out day-to-day processes of surveillance activities, hence, should be improved by retraining. Enhanced laboratory support and electronic transmission would improve data quality and timeliness. Validity of some of the case definitions need to be rechecked. Training Programs should focus on motivating the surveillance personnel.

Sustaining surveillance: evaluating syndromic surveillance in the Pacific

Prior to the 2009 H1N1 pandemic, the Pacific Island Countries and Territories (PICTs) had agreed to develop a standardised, simple syndromic surveillance system to ensure compliance with International Health Regulations requirements (rapid outbreak detection, information sharing and response to outbreaks). In October 2010, the new system was introduced and over the next 12 months implemented in 20 of 22 PICTs. An evaluation was conducted to identify strengths and weaknesses of the system, ease of use and possible points for improvement. An in-country quantitative and qualitative evaluation in five PICTs identified that the most important determinants of the system's success were: simplicity of the system; support from all levels of government; clearly defined roles and responsibilities; feedback to those who collect the data; harmonisation of case definitions; integration of data collection tools into existing health information systems; and availability of clinical and epidemiological advice from external agencies such as the World Health Organization and the Secretariat of the Pacific Community. Regional reporting of alerts, outbreaks and outbreak updates has dramatically increased since implementation of the system. This syndromic system will assist PICTs to detect future influenza pandemics and other emerging infectious diseases and to rapidly contain outbreaks in the Pacific.

Redefining syndromic surveillance

With growing concerns about international spread of disease and expanding use of early disease detection surveillance methods, the field of syndromic surveillance has received increased attention over the last decade. The purpose of this article is to clarify the various meanings that have been assigned to the term syndromic surveillance and to propose a refined categorization of the characteristics of these systems. Existing literature and conference proceedings were examined on syndromic surveillance from 1998 to 2010, focusing on low- and middle-income settings. Based on the 36 unique definitions of syndromic surveillance found in the literature, five commonly accepted principles of syndromic surveillance systems were identified, as well as two fundamental categories: specific and non-specific disease detection. Ultimately, the proposed categorization of syndromic surveillance distinguishes between systems that focus on detecting defined syndromes or outcomes of interest and those that aim to uncover non-specific trends that suggest an outbreak may be occurring. By providing an accurate and comprehensive picture of this field's capabilities, and differentiating among system types, a unified understanding of the syndromic surveillance field can be developed, encouraging the adoption, investment in, and implementation of these systems in settings that need bolstered surveillance capacity, particularly low- and middle-income countries.

Enhanced health event detection and influenza surveillance using a joint Veterans Affairs and Department of Defense biosurveillance application

Background

The establishment of robust biosurveillance capabilities is an important component of the U.S. strategy for identifying disease outbreaks, environmental exposures and bioterrorism events. Currently, U.S. Departments of Defense (DoD) and Veterans Affairs (VA) perform biosurveillance independently. This article describes a joint VA/DoD biosurveillance project at North Chicago-VA Medical Center (NC-VAMC). The Naval Health Clinics-Great Lakes facility physically merged with NC-VAMC beginning in 2006 with the full merger completed in October 2010 at which time all DoD care and medical personnel had relocated to the expanded and remodeled NC-VAMC campus and the combined facility was renamed the Lovell Federal Health Care Center (FHCC). The goal of this study was to evaluate disease surveillance using a biosurveillance application which combined data from both populations.

Methods

A retrospective analysis of NC-VAMC/Lovell FHCC and other Chicago-area VAMC data was performed using the ESSENCE biosurveillance system, including one infectious disease outbreak (Salmonella/Taste of Chicago-July 2007) and one weather event (Heat Wave-July 2006). Influenza-like-illness (ILI) data from these same facilities was compared with CDC/Illinois Sentinel Provider and Cook County ESSENCE data for 2007-2008.

Results

Following consolidation of VA and DoD facilities in North Chicago, median number of visits more than doubled, median patient age dropped and proportion of females rose significantly in comparison with the pre-merger NC-VAMC facility. A high-level gastrointestinal alert was detected in July 2007, but only low-level alerts at other Chicago-area VAMCs. Heat-injury alerts were triggered for the merged facility in June 2006, but not at the other facilities. There was also limited evidence in these events that surveillance of the combined population provided utility above and beyond the VA-only and DoD-only components. Recorded ILI activity for NC-VAMC/Lovell FHCC was more pronounced in the DoD component, likely due to pediatric data in this population. NC-VAMC/Lovell FHCC had two weeks of ILI activity exceeding both the Illinois State and East North Central Regional baselines, whereas Hines VAMC had one and Jesse Brown VAMC had zero.

Conclusions

Biosurveillance in a joint VA/DoD facility showed potential utility as a tool to improve surveillance and situational awareness in an area with Veteran, active duty and beneficiary populations. Based in part on the results of this pilot demonstration, both agencies have agreed to support the creation of a combined VA/DoD ESSENCE biosurveillance system which is now under development.

A Multi-function Public Health Surveillance System and the Lessons Learned in Its Development: The Alberta Real Time Syndromic Surveillance Net

Objective: We describe a centralized automated multi-function detection and reporting system for public health surveillance–the Alberta Real Time Syndromic Surveillance Net (ARTSSN). This improves upon traditional paper-based systems which are often fragmented, limited by incomplete data collection and inadequate analytical capacity, and incapable of providing timely information for public health action.

Methods: ARTSSN concurrently analyzes multiple electronic data sources in real time to describe results in tables, charts and maps. Detected anomalies are immediately disseminated via alerts to decision-makers for action.

Results: ARTSSN provides richly integrated information on a variety of health conditions for early detection of and prompt action on abnormal events such as clusters, outbreaks and trends. Examples of such health conditions include chronic and communicable disease, injury and environmentmediated adverse incidents.

Discussion: Key advantages of ARTSSN over traditional paper-based methods are its timeliness, comprehensiveness and automation. Public health surveillance of communicable disease, injury, environmental hazard exposure and chronic disease now occurs in a single system in real time year round. Examples are given to demonstrate the public health value of this system, particularly during Pandemic (H1N1) 2009.

Analysis of the korean emergency department syndromic surveillance system: mass type acute diarrheal syndrome

OBJECTIVES

This study was designed to compare the data from the emergency department syndromic surveillance system of Korea in detection and reporting of acute diarrheal syndrome (mass type) with the data from the Korea Food and Drug Administration. And to offer fundamental materials for making improvements in current surveillance system was our purpose.

METHODS

A study was conducted by reviewing the number of cases reported as acute diarrheal syndrome (mass type) from the Korean Center for Disease Control and Prevention between June, 2002 and July, 2008. And the data were compared with the number of mass food poisoning cases during the same period, reported from the Korea Food and Drug Administration. The difference between two groups was measured and their transitions were compared.

RESULTS

The emergency department syndromic surveillance system's reports of the numbers of acute diarrheal syndrome (mass type) cases were different from the transition of mass food poisonings, reported by the Korea Food and Drug Administration. Their reports were not accurate and they could not follow the trends of increase in mass food poisonings since 2002.

CONCLUSIONS

Current problems in the emergency department syndromic surveillance system in Korea are mostly related to inaccuracies of daily data reporting system. Manual data input by the reporters could play a big role in such inaccuracies. There need to be improvements in the ways of reporting data, such as automated information transport system linking electronic medical record.

Bioterrorism : A Public Health Perspective

The intentional release or threat of release of biologic agents (i.e. viruses, bacteria, fungi or their toxins) in order to cause disease or death among human population or food crops and livestock to terrorize a civilian population or manipulate the government in the present scenario of increased terrorist activity has become a real possibility. The most important step in the event of a bioterrorist attack is the identification of the event. This can be achieved by generating awareness, having high degree of suspicion and having a good surveillance system to assist quick detection. Bioterrorist attacks could be covert or announced and caused by virtually any pathogenic microorganism. Bioterrorist agents of major concern have been categorized as A, B and C based on the priority of the agents to pose a risk to the national security and the ease with which they can be disseminated. The five phases of activities in dealing with a bioterrorist attack are preparedness phase, early warning phase, notification phase, response phase and recovery phase. A bioterrorism attack in a public place is a public health emergency. Early detection and rapid investigation is the key to contain such attacks. The role of public health epidemiologist is critical not only in determining the scope and magnitude of the attack but also in effective implementation of interventions.

Situational uses of syndromic surveillance

Since 2001, many state and local health departments have implemented automated systems to monitor healthcare use and to promptly identify and track epidemics and other public health threats. In 2007-08, we conducted case studies of selected events with actual or potential public health impacts to determine whether and how health departments and hospitals used these new systems. We interviewed public health and hospital representatives and applied qualitative analysis methods to identify response themes. So-called "syndromic" surveillance methods were most useful in situations with widespread health effects, such as respiratory illness associated with seasonal influenza or exposures to smoke from wildfires. In other instances, such as a tornado or hazardous material exposures, these systems were useful for detecting or monitoring health impacts that affected relatively few people, or they were used to affirm the absence of outbreaks following natural disasters or the detection of a potential pathogen in air samples. Typically, these data supplemented information from traditional sources to provide a timelier or fuller mosaic of community health status, and use was shaped by long-standing contacts between health department and hospital staffs. State or local epidemiologists generally preferred syndromic systems they had developed over the CDC BioSense system, citing lesser familiarity with BioSense and less engagement in its development. Instances when BioSense data were most useful to state officials occurred when analyses and reports were provided by CDC staff. Understanding the uses of surveillance information during such events can inform further investments in surveillance capacity in public health emergency preparedness programs.

Laboratory-Guided Detection of Disease Outbreaks: Three Generations of Surveillance Systems

Context.—Traditional biothreat surveillance systems are vulnerable to incomplete and delayed reporting of public health threats.

Objective.—To review current and emerging approaches to detection and monitoring of biothreats enabled by laboratory methods of diagnosis and to identify trends in the biosurveillance research.

Data Sources.—PubMed (1995 to December 2007) was searched with the combined search terms “surveillance” and “infectious diseases.” Additional articles were identified by hand searching the bibliographies of selected papers. Additional search terms were “public health,” “disease monitoring,” “cluster,” “outbreak,” “laboratory notification,” “molecular,” “detection,” “evaluation,” “genomics,” “communicable diseases,” “geographic information systems,” “bioterrorism,” “genotyping,” and “informatics.” Publication language was restricted to English. The bibliographies of key references were later hand searched to identify articles missing in the database search. Three approaches to infectious disease surveillance that involve clinical laboratories are contrasted: (1) laboratory-initiated infectious disease notifications, (2) syndromic surveillance based on health indicators, and (3) genotyping based surveillance of biothreats. Advances in molecular diagnostics enable rapid genotyping of biothreats and investigations of genes that were not previously identifiable by traditional methods. There is a need for coordination between syndromic and laboratory-based surveillance. Insufficient and delayed decision support and inadequate integration of surveillance signals into action plans remain the 2 main barriers to efficient public health monitoring and response. Decision support for public health users of biosurveillance alerts is often lacking.

Conclusions.—The merger of the 3 scientific fields of surveillance, genomics, and informatics offers an opportunity for the development of effective and rapid biosurveillance methods and tools.

Development of a surveillance case definition for heat-related illness using 911 medical dispatch data

OBJECTIVES

The adverse effects of hot weather on public health are of increasing concern. A surveillance system using 911 medical dispatch data for the detection of heat-related illness (HRI) could provide new information on the impact of excessive heat on the population. This paper describes how we identified medical dispatch call codes, called "determinants", that could represent HRI events.

METHODS

Approximately 500 medical dispatch determinants were reviewed in focus groups composed of Emergency Medical Services (EMS) paramedics, dispatchers, physicians, and public health epidemiologists. Each group was asked to select those determinants that might adequately represent HRI. Selections were then assessed empirically using correlations with daily mean temperature over the study period (June 1-August 31,2005).

RESULTS

The focus groups identified 12 determinant groupings and ranked them according to specificity for HRI. Of these, "Heat/cold exposure" was deemed the most specific. The call determinant groupings with the clearest positive associations with daily mean temperature empirically were "Heat/cold exposure" (Spearman's correlation coefficient (SCC) 0.71, p < 0.0001) and "Unknown problem (man down)" (SCC 0.21, p = 0.04). Within each grouping, the determinant "Unknown status (3rd party caller)" showed significant associations, SCC = 0.34 (p = 0.001) and SCC = 0.22 (p = 0.03) respectively.

CONCLUSIONS

Clinically-informed expertise and empirical evidence both contributed to identification of a group of 911 medical dispatch call determinants that plausibly represent HRI events. Once evaluated prospectively, these may be used in public health surveillance to better understand environmental health impacts on human populations and inform targeted public health interventions.

Syndromic surveillance for influenzalike illness

Emergency department data are currently being used by several syndromic surveillance systems to identify outbreaks of natural or man-made illnesses, and preliminary results suggest that regular outbreaks might be detected earlier with such data than with traditional reporting. This article summarizes a retrospective study of 5 influenza seasons in Ottawa,Canada; time-series analysis was used to look for an association between consultation to the emergency department for influenzalike illness and the isolation of influenza virus in the community. The population studied included both children and adults consulting to 3 local hospitals. In 4 seasons, visits to the emergency department involving children younger than 5 years consulting mainly for fever and for respiratory symptoms peaked 1 to 4 weeks before the isolation of influenza virus in the community. If monitored regularly for the presence of key symptoms, pediatric hospitals might be efficient and cost-effective sentinels of influenza and of other infectious diseases.

Challenges to global surveillance and response to infectious disease outbreaks of international importance

This article presents a notional scheme of global surveillance and response to infectious disease outbreaks and reviews 14 international surveillance and response programs. In combination, the scheme and the programs illustrate how, in an ideal world and in the real world, infectious disease outbreaks of public health significance could be detected and contained. Notable practices and achievements of the programs are cited; these may be useful when instituting new programs or redesigning existing ones. Insufficiencies are identified in four critical areas: health infrastructure; scientific methods and concepts of operation; essential human, technical, and financial resources; and international policies. These insufficiencies challenge global surveillance of and response to infectious disease outbreaks of international importance. This article is intended to help policymakers appreciate the complexity of the problem and assess the impact and cost-effectiveness of proposed solutions. An assessment of the potential contribution of appropriate diagnostic tests to surveillance and response is included.

Code-based syndromic surveillance for influenzalike illness by International Classification of Diseases, Ninth Revision

ICD-9 codes collected automatically in a syndromic system are sensitive and specific in detecting outbreaks caused by respiratory viruses.

With the spread of avian influenza, use of automated data streams to rapidly detect and track human influenza cases has increased. We performed correlation analyses to determine whether International Classification of Diseases, Ninth Revision (ICD-9), groupings used to detect influenzalike illness (ILI) within an automated syndromic system correlate with respiratory virus laboratory test results in the same population (r = 0.71 or 0.86, depending on group). We used temporal and signal-to-noise analysis to identify 2 subsets of ICD-9 codes that most accurately represent ILI trends, compared nationwide sentinel ILI surveillance data from the Centers for Disease Control and Prevention with the automated data (r = 0.97), and found the most sensitive set of ICD-9 codes for respiratory illness surveillance. Our results demonstrate a method for selecting the best group of ICD-9 codes to assist system developers and health officials who are interpreting similar data for daily public health activities.

"Med-X": a medical examiner surveillance model for bioterrorism and infectious disease mortality

We created a model surveillance system (Med-X) designed to enable medical examiners and coroners to recognize fatal infections of public health importance and deaths due to bioterrorism. All individuals who died in New Mexico and fell under medical examiner jurisdiction between November 23, 2000, and November 22, 2002, were prospectively evaluated using sets of surveillance symptoms and autopsy-based pathologic syndromes. All infectious disease deaths were evaluated to identify the specific causative agent. Of 6104 jurisdictional cases, 250 (4.1%) met Med-X criteria, of which 141 (56.4%) had a target pathologic syndrome. Ultimately, 127 (51%) of the 250 cases were due to infections. The causative organism was identified for 103 (81%) of the infectious disease deaths, of which 60 (58.3%) were notifiable conditions in New Mexico. Flu-like symptoms, fever and respiratory symptoms, and encephalopathy or new-onset seizures had predictive values positive for fatal infections of 65%, 72%, and 50%, respectively, and are useful as autopsy performance criteria. Before the development of surveillance criteria, 37 (14.8%) of the cases ordinarily would not have been autopsied resulting in a 1% increase in autopsy workload. Med-X is an effective method of detecting infectious disease deaths among medical examiner cases. Uniform criteria for performing medical examiner autopsies and reporting cases to public health authorities enhance surveillance for notifiable infectious diseases and increase the likelihood of recognizing deaths related to bioterrorism.

Direct cost associated with the development and implementation of a local syndromic surveillance system

OBJECTIVE

Enhancing public health surveillance to include electronic syndromic surveillance systems has received increased attention in recent years. Although cost continually serves as a critical factor in public health decision making, few studies have evaluated direct costs associated with syndromic surveillance systems. In this study, we calculated the direct costs associated with developing and implementing a syndromic surveillance system in Boston, Massachusetts, from the perspective of local, state, and federal governments.

METHODS

Between December 2003 and July 2005, the Boston Public Health Commission (BPHC), in collaboration with the Centers for Disease Control and Prevention (CDC), and the Massachusetts Department of Public Health developed a syndromic surveillance system in which limited demographic and chief complaint data are collected from all Boston acute care emergency departments every 24 hours. Costs were divided into three categories: development, operation, and upgrade. Within these categories, all fixed and variable costs incurred by both BPHC and CDC were assessed, including those associated with development of syndromic surveillance-related city regulations and system enhancements.

RESULTS

The total estimated direct cost of system development and implementation during the study period was $422,899 ($396,716 invested by BPHC and $26,183 invested by CDC). Syndromic system enhancements to improve situational awareness accounted for $74,389.

CONCLUSION

Development, implementation, and operation of a syndromic surveillance system accounted for a relatively small proportion of surveillance costs in a large urban health department. Funding made available for a future cost-benefit analysis, and an assessment of local epidemiologic capacity will help to guide decisions for local health departments. Although not a replacement for traditional surveillance, syndromic surveillance in Boston is an important and relatively inexpensive component of a comprehensive local public health surveillance system.

Syndromic surveillance for emerging infections in office practice using billing data

PURPOSE

We wanted to evaluate the feasibility of conducting syndromic surveillance in a primary care office using billing data.

METHODS

A 1-year study was conducted in a primary care practice; comparison data were obtained from emergency department records of visits by county residents. Within the practice, a computer program converted billing data into de-identified daily summaries of International Classification of Diseases, Ninth Revision (ICD-9) codes by sex and age-group; and a staff member generated daily summaries and e-mailed them to the analysis team. For both the practice and the emergency departments, infection-related syndromes and practice-specific thresholds were calculated using the category 1 syndrome codes and an analytical method based upon the Early Aberration Reporting System of the Centers for Disease Control and Prevention.

RESULTS

A mean of 253 ICD-9 codes per day was reported. The most frequently recorded syndromes were respiratory illness, gastrointestinal illness, and fever. Syndromes most commonly exceeding the threshold of 2 standard deviations for the practice were lymphadenitis, rash, and fever. Generating a daily summary took 1 to 2 minutes; the program was written by the software vendor for a fee of dollar 1,500. During the 2003-2004 influenza season, trend line patterns of the emergency department visits reflected a pattern consistent with that of the state, whereas the trend line in primary case practice cases was less consistent, reflecting the variation expected in data from a single clinic. Still, spikes of activity that occurred in the practice before the emergency department suggest the practice may have seen patients with influenza earlier.

CONCLUSIONS

This preliminary study showed the feasibility of implementing syndromic surveillance in an office setting at a low cost and with minimal staff effort. Although many implementation issues remain, further development of syndromic surveillance systems should include primary care offices.

Gram-positive rod surveillance for early anthrax detection

Connecticut established telephone-based gram-positive rod (GPR) reporting primarily to detect inhalational anthrax cases more quickly. From March to December 2003, annualized incidence of blood isolates was 21.3/100,000 persons; reports included 293 Corynebacterium spp., 193 Bacillus spp., 73 Clostridium spp., 26 Lactobacillus spp., and 49 other genera. Around-the-clock GPR reporting has described GPR epidemiology and enhanced rapid communication with clinical laboratories.

Diarrheal illness detected through syndromic surveillance after a massive power outage: New York City, August 2003

OBJECTIVES

We investigated increases in diarrheal illness detected through syndromic surveillance after a power outage in New York City on August 14, 2003.

METHODS

The New York City Department of Health and Mental Hygiene uses emergency department, pharmacy, and absentee data to conduct syndromic surveillance for diarrhea. We conducted a case-control investigation among patients presenting during August 16 to 18, 2003, to emergency departments that participated in syndromic surveillance. We compared risk factors for diarrheal illness ascertained through structured telephone interviews for case patients presenting with diarrheal symptoms and control patients selected from a stratified random sample of nondiarrheal patients.

RESULTS

Increases in diarrhea were detected in all data streams. Of 758 patients selected for the investigation, 301 (40%) received the full interview. Among patients 13 years and older, consumption of meat (odds ratio [OR]=2.7, 95% confidence interval [CI]=1.2, 6.1) and seafood (OR=4.8; 95% CI=1.6, 14) between the power outage and symptom onset was associated with diarrheal illness.

CONCLUSIONS

Diarrhea may have resulted from consumption of meat or seafood that spoiled after the power outage. Syndromic surveillance enabled prompt detection and systematic investigation of citywide illness that would otherwise have gone undetected.

Classification of emergency department chief complaints into 7 syndromes: a retrospective analysis of 527,228 patients

STUDY OBJECTIVE

Electronic surveillance systems often monitor triage chief complaints in hopes of detecting an outbreak earlier than can be accomplished with traditional reporting methods. We measured the accuracy of a Bayesian chief complaint classifier called CoCo that assigns patients 1 of 7 syndromic categories (respiratory, botulinic, gastrointestinal, neurologic, rash, constitutional, or hemorrhagic) based on free-text triage chief complaints.

METHODS

We compared CoCo's classifications with criterion syndromic classification based on International Classification of Diseases, Ninth Revision (ICD-9) discharge diagnoses. We assigned the criterion classification to a patient based on whether the patient's primary diagnosis was a member of a set of ICD-9 codes associated with CoCo's 7 syndromes. We tested CoCo's performance on a set of 527,228 chief complaints from patients registered at the University of Pittsburgh Medical Center emergency department (ED) between 1990 and 2003. We performed a sensitivity analysis by varying the ICD-9 codes in the criterion standard. We also tested CoCo on chief complaints from EDs in a second location (Utah).

RESULTS

Approximately 16% (85,569/527,228) of the patients were classified according to the criterion standard into 1 of the 7 syndromes. CoCo's classification performance (number of cases by criterion standard, sensitivity [95% confidence interval (CI)], and specificity [95% CI]) was respiratory (34,916, 63.1 [62.6 to 63.6], 94.3 [94.3 to 94.4]); botulinic (1,961, 30.1 [28.2 to 32.2], 99.3 [99.3 to 99.3]); gastrointestinal (20,431, 69.0 [68.4 to 69.6], 95.6 [95.6 to 95.7]); neurologic (7,393, 67.6 [66.6 to 68.7], 92.7 [92.6 to 92.8]); rash (2,232, 46.8 [44.8 to 48.9], 99.3 [99.3 to 99.3]); constitutional (10,603, 45.8 [44.9 to 46.8], 96.6 [96.6 to 96.7]); and hemorrhagic (8,033, 75.2 [74.3 to 76.2], 98.5 [98.4 to 98.5]). The sensitivity analysis showed that the results were not affected by the choice of ICD-9 codes in the criterion standard. Classification accuracy did not differ on chief complaints from the second location.

CONCLUSION

Our results suggest that, for most syndromes, our chief complaint classification system can identify about half of the patients with relevant syndromic presentations, with specificities higher than 90% and positive predictive values ranging from 12% to 44%.

A review of strategies for enhancing the completeness of notifiable disease reporting

Notifiable disease surveillance systems provide essential data for infectious disease prevention and control programs at the local, state, and national levels. Given that reporting completeness is known to vary considerably, this review identifies methods that can reliably enhance completeness of reporting. These surveillance-related activities include initiating active surveillance when appropriate; implementing automated, electronic laboratory-based reporting; strengthening ties with clinicians and other key partners in notifiable disease reporting; and increasing the use of laboratory diagnostic tests in identifying new cases. Despite ample data in support of these strategies, notifiable disease surveillance continues to receive insufficient attention and resources. Recent attention to public health preparedness provides an opportunity to strengthen notifiable disease surveillance and enhance completeness of reporting.

The validity of chief complaint and discharge diagnosis in emergency department-based syndromic surveillance

OBJECTIVE

Emergency department (ED)-based syndromic surveillance systems are being used by public health departments to monitor for outbreaks of infectious diseases, including bioterrorism; however, few systems have been validated. The authors evaluated a "drop-in" syndromic surveillance system by comparing syndrome categorization in the ED with chief complaints and ED discharge diagnoses from medical record review.

METHODS

A surveillance form was completed for each ED visit at 15 participating Arizona hospitals between October 27 and November 18, 2001. Each patient visit was assigned one of ten clinical syndromes or "none." For six of 15 EDs, kappa statistics were used to compare syndrome agreement between surveillance forms and syndrome categorization with chief complaint and ED discharge diagnosis from medical record review.

RESULTS

Overall, agreement between surveillance forms and ED discharge diagnoses (kappa = 0.55; 95% confidence interval [CI] = 0.52 to 0.59) was significantly higher than between surveillance forms and chief complaints (kappa = 0.48; 95% CI = 0.44 to 0.52). Agreement between chief complaints and ED discharge diagnoses was poor for respiratory tract infection with fever (kappa = 0.33; 95% CI = 0.27 to 0.39). Furthermore, pediatric chief complaints showed lower agreement for respiratory tract infection with fever when compared with adults (kappa = 0.34 [95% CI = 0.20 to 0.47] vs. kappa = 0.44 [95% CI = 0.28 to 0.59], respectively).

CONCLUSIONS

In general, this syndromic surveillance system classified patients into appropriate syndrome categories with fair to good agreement compared with chief complaints and discharge diagnoses. The present findings suggest that use of ED discharge diagnoses, in addition to or instead of chief complaints, may increase surveillance validity for both automated and drop-in syndromic surveillance systems.