Developing syndrome definitions based on consensus and current use.

OBJECTIVE: Standardized surveillance syndromes do not exist but would facilitate sharing data among surveillance systems and comparing the accuracy of existing systems. The objective of this study was to create reference syndrome definitions from a consensus of investigators who currently have or are building syndromic surveillance systems. DESIGN: Clinical condition-syndrome pairs were catalogued for 10 surveillance systems across the United States and the representatives of these systems were brought together for a workshop to discuss consensus syndrome definitions. RESULTS: Consensus syndrome definitions were generated for the four syndromes monitored by the majority of the 10 participating surveillance systems: Respiratory, gastrointestinal, constitutional, and influenza-like illness (ILI). An important element in coming to consensus quickly was the development of a sensitive and specific definition for respiratory and gastrointestinal syndromes. After the workshop, the definitions were refined and supplemented with keywords and regular expressions, the keywords were mapped to standard vocabularies, and a web ontology language (OWL) ontology was created. LIMITATIONS: The consensus definitions have not yet been validated through implementation. CONCLUSION: The consensus definitions provide an explicit description of the current state-of-the-art syndromes used in automated surveillance, which can subsequently be systematically evaluated against real data to improve the definitions. The method for creating consensus definitions could be applied to other domains that have diverse existing definitions.

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.

Seasonal trends of human parainfluenza viral infections: United States, 1990-2004.

BACKGROUND: Human parainfluenza viruses (HPIVs) are important causes of upper and lower respiratory tract illness among children and adults. METHODS: We describe seasonal trends for individual HPIV serotypes and respiratory syncytial virus in the United States using data on the percentage of specimens with positive test results reported to the National Respiratory and Enteric Viruses Surveillance System during the period 1990-2004. Onset and conclusion dates for peaks in activity were determined with the Early Aberration Reporting System's cumulative sum method C2 by detecting periods when the number of positive HPIV test results was significantly greater than that observed for preceding weeks for each serotype. RESULTS: During the study period, increases in the percentage of positive HPIV-3 and HPIV-2 test results occurred annually during April-June and October-November, respectively. Increases in the percentage of positive HPIV-1 test results occurred biennially during September-December during odd-numbered years. During years when HPIV-1 was not circulating, more HPIV-3 activity was reported, either as a longer spring season or as a second smaller period of increased activity noted in the fall. Seasonal peaks in respiratory syncytial virus activity occurred annually during November-April. CONCLUSIONS: We provide a national perspective for HPIV activity during the 15-year study period and demonstrate distinct seasonal peaks in activity for HPIV-1, HPIV-2, and HPIV-3. In addition, our data suggest that there is an interaction between HPIV-3 and HPIV-1 activity, which may have implications in future prevention strategies.

Multifaceted syndromic surveillance in a public health department using the early aberration reporting system.

Local health departments concerned with early detection of potential terrorist threats are beginning to explore novel approaches to syndromic surveillance. Using the Early Aberration Reporting System (EARS) developed by the Centers for Disease Control and Prevention, a metropolitan health department in Tennessee and five community partners have agreed to exchange data in order to implement a multifaceted syndromic surveillance system for early detection of a biological attack. This article describes how we used EARS as the foundation for implementing a surveillance system that encompasses a rich variety of data sources. We address technical requirements for operating EARS, recommend staffing and training prerequisites, describe the involvement of our data partners, and provide details related to data transfer and analysis, review, and response protocol. Other health departments may find this information useful as a general model for implementing EARS-based syndromic surveillance systems in their own jurisdictions.

Comparing aberration detection methods with simulated data.

We compared aberration detection methods requiring historical data to those that require little background by using simulated data. Methods that require less historical data are as sensitive and specific as those that require 3-5 years of data. These simulations can determine which method produces appropriate sensitivity and specificity.

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.

Prior antimicrobial agent use increases the risk of sporadic infections with multidrug-resistant Salmonella enterica serotype Typhimurium: a FoodNet case-control study, 1996-1997.

Several strains of multidrug-resistant (MDR) Salmonella serotype Typhimurium, including MDR S. Typhimurium definitive type 104, cause almost 10% of Salmonella infections among humans in the United States. To determine the risk factors for acquiring sporadic MDR S. Typhimurium infection, we conducted a population-based, case-control study using data from the Foodborne Diseases Active Surveillance Network (FoodNet) during 1996-1997. S. Typhimurium isolates from 5 FoodNet surveillance areas (California, Connecticut, Georgia, Minnesota, and Oregon) were tested for antimicrobial resistance and phage typing. Telephone interviews were conducted with ill persons and matched control subjects. Compared with both control subjects and patients infected with pansensitive strains of S. Typhimurium, patients with MDR S. Typhimurium infection were significantly more likely to have received an antimicrobial agent, particularly an agent to which the Salmonella isolate was resistant, during the 4 weeks preceding illness onset. Prudent antimicrobial agent use among humans and among veterinarians and food-animal producers is necessary to reduce the burden of drug-resistant salmonellosis in humans.

Reptiles, amphibians, and human Salmonella infection: a population-based, case-control study.

To estimate the burden of reptile- and amphibian-associated Salmonella infections, we conducted 2 case-control studies of human salmonellosis occurring during 1996-1997. The studies took place at 5 Foodborne Diseases Active Surveillance Network (FoodNet) surveillance areas: all of Minnesota and Oregon and selected counties in California, Connecticut, and Georgia. The first study included 463 patients with serogroup B or D Salmonella infection and 7618 population-based controls. The second study involved 38 patients with non-serogroup B or D Salmonella infection and 1429 controls from California only. Patients and controls were interviewed about contact with reptiles and amphibians. Reptile and amphibian contact was associated both with infection with serogroup B or D Salmonella (multivariable odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1-2.2; P<.009) and with infection with non-serogroup B or D Salmonella (OR, 4.2; CI, 1.8-9.7; P<.001). The population attributable fraction for reptile or amphibian contact was 6% for all sporadic Salmonella infections and 11% among persons <21 years old. These data suggest that reptile and amphibian exposure is associated with approximately 74,000 Salmonella infections annually in the United States.

Implementing syndromic surveillance: a practical guide informed by the early experience.

Syndromic surveillance refers to methods relying on detection of individual and population health indicators that are discernible before confirmed diagnoses are made. In particular, prior to the laboratory confirmation of an infectious disease, ill persons may exhibit behavioral patterns, symptoms, signs, or laboratory findings that can be tracked through a variety of data sources. Syndromic surveillance systems are being developed locally, regionally, and nationally. The efforts have been largely directed at facilitating the early detection of a covert bioterrorist attack, but the technology may also be useful for general public health, clinical medicine, quality improvement, patient safety, and research. This report, authored by developers and methodologists involved in the design and deployment of the first wave of syndromic surveillance systems, is intended to serve as a guide for informaticians, public health managers, and practitioners who are currently planning deployment of such systems in their regions.

The bioterrorism preparedness and response Early Aberration Reporting System (EARS).

Data from public health surveillance systems can provide meaningful measures of population risks for disease, disability, and death. Analysis and evaluation of these surveillance data help public health practitioners react to important health events in a timely manner both locally and nationally. Aberration detection methods allow the rapid assessment of changes in frequencies and rates of different health outcomes and the characterization of unusual trends or clusters. The Early Aberration Reporting System (EARS) of the Centers for Disease Control and Prevention allows the analysis of public health surveillance data using available aberration detection methods. The primary purpose of EARS is to provide national, state, and local health departments with several alternative aberration detection methods. EARS helps assist local and state health officials to focus limited resources on appropriate activities during epidemiological investigations of important public health events. Finally, EARS allows end users to select validated aberration detection methods and modify sensitivity and specificity thresholds to values considered to be of public health importance by local and state health departments.

Enhanced drop-in syndromic surveillance in New York City following September 11, 2001.

After the 2001 World Trade Center disaster, the New York City Department of Health was under heightened alert for bioterrorist attacks in the city. An emergency department (ED) syndromic surveillance system was implemented with the assistance of the Centers for Disease Control and Prevention to ensure early recognition of an increase or clustering of disease syndromes that might represent a disease outbreak, whether natural or intentional. The surveillance system was based on data collected 7 days a week at area EDs. Data collected were translated into syndromes, entered into an electronic database, and analyzed for aberrations in space and time within 24 hours. From September 14-27, personnel were stationed at 15 EDs on a 24-hour basis (first staffing period); from September 29-October 12, due to resource limitations, personnel were stationed at 12 EDs on an 18-hour basis (second staffing period). A standardized form was used to obtain demographic information and classify each patient visit into 12 syndrome categories. Seven of these represented early manifestations of bioterrorist agents. Data transfer and analysis for time and space clustering (alarms) by syndrome and age occurred daily. Retrospective analyses examined syndrome trends, differences in reporting between staffing periods, and the staff's experience during the project. A total of 67,536 reports were received. The system captured 83.9% of patient visits during the first staffing period, and 60.8% during the second staffing period (P < 0.01). Five syndromes each accounted for more than 1% of visits: trauma, asthma, gastrointestinal illness, upper/lower respiratory infection with fever, and anxiety. Citywide temporal alarms occurred eight times for three of the major bioterrorism-related syndromes. Spatial clustering alarms occurred 16 times by hospital location and 9 times by ZIP code for the same three syndromes. No outbreaks were detected. On-site staffing to facilitate data collection and entry, supported by daily analysis of ED visits, is a feasible short-term approach to syndromic surveillance during high-profile events. The resources required to operate such a system, however, cannot be sustained for the long term. This system was changed to an electronic-based ED syndromic system using triage log data that remains in operation.

Seroincidence of Helicobacter pylori infection in a cohort of rural Bolivian children: acquisition and analysis of possible risk factors.

High seroprevalence rates for Helicobacter pylori are reported in developing countries, yet few seroincidence studies exist that determine age of initial acquisition and risk factors for H. pylori seroconversion. Two H. pylori serosurveys were conducted in August 1996 and November 1997. Of 188 children aged 21 months to 6 years who were seronegative in the first survey, 44 (23%) had seroconverted at follow-up, yielding an 18% annual seroincidence. The largest increase in seroincidence occurred between children aged 2 years (10%) and children aged 3 years (32%). Use of a lidded, narrow-mouthed water vessel was protective against seroconversion (odds ratio [OR], 0.3; 95% confidence interval [CI], 0.1-0.8), and the presence of another H. pylori-seropositive sibling in the household was a risk factor for seroconversion (OR, 3.1; 95% CI, 1.3-8.7). Although not a randomized intervention trial, this study suggests that the use of a narrow-mouthed water vessel may prevent the transmission of H. pylori in households in developing countries.

Diarrhea prevention through household-level water disinfection and safe storage in Zambia.

A water quality intervention that consists of water treatment, safe storage, and community education was field tested in Kitwe, Zambia. A total of 166 intervention households were randomly selected from one community and 94 control households from another. Baseline surveys were conducted and the intervention was distributed. Weekly active diarrhea surveillance, biweekly water testing, and a follow-up survey were conducted. Compliance was high in intervention households: 97% reported using disinfectant and 72-95% had measurable chlorine in their water in biweekly testing. The percentage of intervention households storing water safely increased from 41.5% to 89.2%. Stored water in intervention households was significantly less contaminated with Escherichia coli than water in control households (P < 0.001). Diarrheal disease risk for individuals in intervention households was 48% lower than for controls (95% confidence interval = 0.3, 0.9). This intervention is a useful tool for preventing waterborne diseases in families in developing countries who lack access to potable water.

Serratia marcescens bacteremia traced to an infused narcotic.

BACKGROUND: From June 30, 1998, through March 21, 1999, several patients in the surgical intensive care unit of a hospital acquired Serratia marcescens bacteremia. We investigated this outbreak. METHODS: A case was defined as the occurrence of S. marcescens bacteremia in any patient in the surgical intensive care unit during the period of the epidemic. To identify risk factors, we compared patients with S. marcescens bacteremia with randomly selected controls. Isolates from patients and from medications were evaluated by pulsed-field gel electrophoresis. The hair of one employee was tested for fentanyl. RESULTS: Twenty-six patients with S. marcescens bacteremia were identified; eight (31 percent) had polymicrobial bacteremia, and seven of these had Enterobacter cloacae and S. marcescens in the same culture. According to univariate analysis, patients with S. marcescens bacteremia stayed in the surgical intensive care unit longer than controls (13.5 vs. 4.0 days, P<0.001), were more likely to have received fentanyl in the surgical intensive care unit (odds ratio, 31; P<0.001), and were more likely to have been exposed to two particular respiratory therapists (odds ratios, 13.1 and 5.1; P<0.001 for both comparisons). In a multivariate analysis, receipt of fentanyl and exposure to the two respiratory therapists (adjusted odds ratio for one therapist, 6.7; P=0.002; adjusted odds ratio for the other therapist, 9.5; P=0.02) remained significant. One respiratory therapist had been reported for tampering with fentanyl; his hair sample tested positive for fentanyl. Cultures of fentanyl infusions from two case patients yielded S. marcescens and E. cloacae. The isolates from the case patients and from the fentanyl infusions had similar patterns on pulsed-field gel electrophoresis. After removal of the implicated respiratory therapist, no further cases occurred. CONCLUSIONS: An outbreak of S. marcescens and E. cloacae bacteremia in a surgical intensive care unit was traced to extrinsic contamination of the parenteral narcotic fentanyl by a health care worker. Our findings underscore the risk of complications in patients that is associated with illicit narcotic use by health care workers.