Traditional Public Health Surveillance Research Articles

Use of Unstructured Event-Based Reports for Global Infectious Disease Surveillance

Free or low-cost sources of unstructured information, such as Internet news and online discussion sites, provide detailed local and near real-time data on disease outbreaks, even in countries that lack traditional public health surveillance. To improve public health surveillance and, ultimately, interventions, we examined 3 primary systems that process event-based outbreak information: Global Public Health Intelligence Network, HealthMap, and EpiSPIDER. Despite similarities among them, these systems are highly complementary because they monitor different data types, rely on varying levels of automation and human analysis, and distribute distinct information. Future development should focus on linking these systems more closely to public health practitioners in the field and establishing collaborative networks for alert verification and dissemination. Such development would further establish event-based monitoring as an invaluable public health resource that provides critical context and an alternative to traditional indicator-based outbreak reporting.

Tracking Associations Between Ambient Ozone and Asthma-Related Emergency Department Visits Using Case-Crossover Analysis

Traditional environmental public health surveillance consists of separately measuring hazards, exposures, and health outcomes. The Environmental Public Health Tracking (EPHT) Network seeks to accrue additional information by linking hazard or exposure data to health outcomes data. A natural progression is to consider tracking the "link" itself, that is, to track the association between an environmental hazard and a health outcome. The Maine EPHT Program conducted a case-crossover analysis to measure associations between daily estimated ambient ozone and particulate matter (PM2.5) and asthma-related emergency department (ED) visits for 2000-2003. We found an overall association of 7 percent (95% confidence interval, 4-11) excess asthma-related ED visits per 10-ppb increase in ozone averaged over 4 days (lag 0-3). The association was positive in the first 3 years and negative in the last. The excess risk was concentrated among females aged 15 to 34 and males younger than 15. The methodology for tracking associations between ambient air quality and acute morbidity is not generalizable to most other EPHT topic areas, but there are ample reasons to pursue this activity. The analysis can potentially help evaluate the effectiveness of regulatory and intervention programs, as well as inform us about trends, sensitive subpopulations, and changing potency of air constituents.

Detection and Early Identification in Bioterrorism Events

Syndromic surveillance, collecting and analyzing symptoms before diagnosis, has the potential to identify bioterrorist attacks in a timely, flexible, and specific manner. Nurses are important resources in collecting and interpreting surveillance data. Clinical skills in early diagnosis may identify a bioterrorist attack before surveillance systems and independently trigger investigations. Computerized syndromic surveillance systems are difficult to sustain and are not in use nationwide. Traditional public health surveillance is not replaced by syndromic surveillance. Weaknesses remain in surveillance related to bioterrorism preparedness. Bioterrorist events must be recognized in a timely manner, but this is dependent on sufficient funding for training, equipment, and personnel.

Modeling emergency department visit patterns for infectious disease complaints: results and application to disease surveillance

BackgroundConcern over bio-terrorism has led to recognition that traditional public health surveillance for specific conditions is unlikely to provide timely indication of some disease outbreaks, either naturally occurring or induced by a bioweapon. In non-traditional surveillance, the use of health care resources are monitored in "near real" time for the first signs of an outbreak, such as increases in emergency department (ED) visits for respiratory, gastrointestinal or neurological chief complaints (CC).MethodsWe collected ED CCs from 2/1/94 – 5/31/02 as a training set. A first-order model was developed for each of seven CC categories by accounting for long-term, day-of-week, and seasonal effects. We assessed predictive performance on subsequent data from 6/1/02 – 5/31/03, compared CC counts to predictions and confidence limits, and identified anomalies (simulated and real).ResultsEach CC category exhibited significant day-of-week differences. For most categories, counts peaked on Monday. There were seasonal cycles in both respiratory and undifferentiated infection complaints and the season-to-season variability in peak date was summarized using a hierarchical model. For example, the average peak date for respiratory complaints was January 22, with a season-to-season standard deviation of 12 days. This season-to-season variation makes it challenging to predict respiratory CCs so we focused our effort and discussion on prediction performance for this difficult category. Total ED visits increased over the study period by 4%, but respiratory complaints decreased by roughly 20%, illustrating that long-term averages in the data set need not reflect future behavior in data subsets.ConclusionWe found that ED CCs provided timely indicators for outbreaks. Our approach led to successful identification of a respiratory outbreak one-to-two weeks in advance of reports from the state-wide sentinel flu surveillance and of a reported increase in positive laboratory test results.

Supplementing tuberculosis surveillance with automated data from health maintenance organizations.

Data collected by health maintenance organizations (HMOs), which provide care for an increasing number of persons with tuberculosis (TB), may be used to complement traditional TB surveillance. We evaluated the ability of HMO-based surveillance to contribute to overall TB reporting through the use of routinely collected automated data for approximately 350,000 HMO members. During approximately 1.5 million person-years, 45 incident cases were identified in either HMO or public health department records. Eight (18%) confirmed cases had not been identified by the public health department. The most useful screening criterion (sensitivity of 89% and predictive value positive of 30%) was dispensing of two or more TB drugs. Pharmacy dispensing information routinely collected by many HMOs appears to be a useful adjunct to traditional TB surveillance, particularly for identifying cases without positive microbiologic results that may be missed by traditional public health surveillance methods.

A weapon-related injury surveillance system in New York City

Context: Assault injuries and deaths are a major public health problem in New York City but they are poorly understood because there is a dearth of information concerning them. Objective: Develop and implement a low-cost, efficient, permanent weapon-related injury surveillance system (WRISS) for the city. Design: WRISS was established, using a hierarchical exclusionary model, to capture all weapon-related (gunshot, stab, blunt instrument trauma) mortality and morbidity. Setting: The five boroughs of New York City: The Bronx, Brooklyn, Manhattan, Queens, and Staten Island. Participants: NYC Vital Statistics Office, New York State hospital discharge database, Statewide Planning and Research Cooperative Systems (SPARCS), hospital emergency departments, and the police department. Main Outcome Measures: Surveillance system simplicity, acceptability, flexibility, cost. Results: NYC WRISS is a simple surveillance system depending on both existing data sources and active data collection, and is therefore acceptable to providers. It is flexible and has allowed assault injuries without weapons to be added to better reflect domestic assaults. The cost is low, less than $60,000 per year. Conclusions: NYC WRISS is an efficient, cost-effective surveillance system, particularly suited to big cities with many assault injuries. Its low cost and obvious importance as a public health tool have allowed for its institutionalization, reflected by a permanent health department position, and annual reports alongside the more traditional public health surveillance systems. Analyses of data from 1990 to 1996 have lent new understanding to the decrease in homicides and assaults in New York City during that period.