Influenza

To evaluate whether a rise or shift in severe morbidity and mortality by influenza can be detected with syndromic surveillance.

The 2003-2004 influenza season was notable for the early, intense and widespread circulation of a Type A drift variant and a resulting rush on vaccine followed by an abrupt decrease in activity by mid-January. By contrast, the 2004-2005 influenza season began with a national vaccine shortage preceding any influenza activity with the resulting need for close monitoring of influenza activity.

The Connecticut Department of Public Health developed its first syndromic surveillance system in September 2001 to monitor for possible bioterrorism events and emerging infections. This system, known as the Hospital Admissions Surveillance System, receives daily reports from all 32 Connecticut acute care hospitals on their total unscheduled admissions in various diagnostic/syndromic categories. Information from one category, pneumonia admissions, has been tracked throughout the last four years as an indicator of influenza activity. The information has been utilized to supplement data from laboratory-confirmed influenza testing. The contrasts between the 2003-04 and 2004-05 influenza seasons provided an opportunity to further examine the specificity of changes in pneumonia admissions as an index of severe influenza activity.

Objective

This paper examines the continued usefulness through the 2004-05 influenza season of a hospital admissions-based syndromic surveillance system as a supplement to laboratory surveillance to monitor severe influenza.

Seasonal influenza accounts for a high proportion of outpatient morbidity during the winter months. However, influenza case counts are greatly underestimated due to frequently undiagnosed influenza. Electronic medical record (EMR) systems provide a very large, complex data source for influenza surveillance at both the patient and population level. It is important to identify influenza patients for specimen collection, respiratory isolation for school age children, prescription of an appropriate influenza drug, or to identify patients at risk for complications. At a population level, public health agencies monitor the tempo and spread of influenza season for resource management, as well as maintain situational awareness for avian influenza.

Objective

The objective of this work was to evaluate the utility of classification tree methods for syndromic surveillance case definition development using an EMR system as a data source.

Four waves of pandemic influenza from 1918-1920 in New York City caused ~40,000 deaths, primarily of young-adults and children. The explosiveness of the autumn 1918 wave has led many to believe that in the event of a similar pandemic today early detection and intervention strategies may not be effective. Recent historical studies of the 1918 pandemic, however, provide evidence of controllable transmissibility, of a limited early wave4, and of social distancing measures significantly reducing pandemic impact in many US cities. Importantly, mitigation efforts initiated after the beginning of community-wide transmission (even up to the point of 3-6% of a population being infected) significantly reduced the total impact in 1918.

Objective

In response to an Institute of Medicine report recommending community-based pandemic influenza mitigation strategies be informed by surveillance and disease modeling, we aimed to assess the feasibility of using emergency department data to identify model derived threshold triggers for initiating intervention efforts in the event of a 1918-like pandemic.

In Connecticut, several syndromic surveillance systems have been established to detect and monitor potential public health threats: 1) the hospital admissions syndromic surveillance (HASS) system in 2001; and 2) the emergency department syndromic surveillance (EDSS) system in 2004. For the HASS, hospitals manually categorize unscheduled admissions into 11 syndrome categories and report these aggregate counts through an internet-based system daily to DPH; all 32 hospitals participate. For the EDSS, hospitals electronically report deidentified emergency department chief complaint data to DPH, and using a computerized algorithm, DPH categorizes this data into 8 syndrome categories; currently 17 hospitals participate. As part of pandemic influenza planning, there has been an increased focus on situational awareness at the state and national level; Connecticut would likely rely on these two systems for this purpose.

Objective

To evaluate the performance of the HASS and EDSS systems in reflecting seasonal influenza activity in Connecticut and, thus, their possible utility during a pandemic.

It has been noted since the era of Hippocrates that weather conditions at a specific location can influence the incidence of various infectious and noninfectious diseases. It has also been implied that variations in weather conditions influence the number of cases of infectious respiratory conditions. Syndromic surveillance was introduced in Athens, Greece, for the first time in July 2002 in the framework of increased preparedness for the Olympic Games of 2004. Our experience showed that the incidence of some syndromes parallels that of diseases surveyed by the mandatory notification system of the Hellenic Center for Diseases Control and Prevention that are known to have a strong seasonal pattern in their incidence e.g. influenza. Influenza incidence peaks at the same time with the “respiratory infection with fever” syndrome during spring. This study aimed at investigating possible relationships between the incidence of the “respiratory infection with fever” syndrome and meteorological parameters.

Objective

This study explores the possible impact of meteorological conditions on the incidence of clinical syndromes with an interest for public health in the basin of Athens, Greece.

To evaluate the potential of using the sales of Over the Counter (OTC) medicines for early detection of infections of public health concern, retrospective analysis of the sales of OTC common cold medications used for influenza-like illness (ILI) has been carried out in Japan since 2003. This presentation assess correlations and predictability of OTC sales to ILI for 2004-05 influenza season and compares with the results from 2003-04 season to discuss on robustness and versatility of OTC sales surveillance.

One of the most important goals of disease surveillance is to identify the "what" and "when" of an epidemic. Influenza surveillance is made difficult by inconsistent laboratory testing, deficiencies in testing techniques, and coding subjectivity in hospital records. We hypothesized that respiratory diseases other than influenza may serve as a useful proxy for this infection in pediatric populations, due to similarities in the seasonal characteristics of these illnesses.

Our purpose was to develop an ROC curve for public health surveillance similar to those used in diagnostic testing. We developed syndrome surveillance algorithms with differing sensitivity and specificity in detecting the seasonal influenza (ILI) outbreak. For each algorithm we plotted: days to detect the event against the numbers of false positive alarms during the non-ILI season.

This paper describes the initiation, development and proof-of-concept phase of the ISDS DiSTRIBuTE influenza morbidity surveillance project [1].