Communicable Disease

Monitoring Influenza in Kent County

In General

Influenza causes an average of 36,000 deaths a year in the United States, and more than 200,000 people have to be admitted to the hospital as a result of influenza. Seasonal influenza infections are generally more common among children, however, individuals 65 years of age and older are more likely to suffer from severe illness, potentially leading to death. In Kent County, there were 90 deaths in 2007 from influenza or pneumonia; 91% of these deaths occurred in the population 65 years of age and older. Influenza/pneumonia was the 7th most common cause of death in Kent County in 2007.

Last Year

With the emergence of the novel influenza A (H1N1) virus in the spring of 2009, the 2008-2009 influenza season in Kent County was unlike any we have seen in recent history. During 2008-09, seasonal influenza season peaked during the last week of February/first week of March. By the end of April (the typical end to the influenza season), the Kent County Health Department received 261 reports of laboratory confirmed cases of influenza (compared to 579 reports received during the 2006-07 influenza season). During the month of May, an additional 276 cases of influenza were reported to KCHD. Minor influenza activity continued through the summer and at the end of August, the total number of influenza cases reported during the very unique influenza season of 2008-2009 totaled 556, with 57 of those cases testing positive for the novel influenza A (H1N1) virus.

Through the end of April, schools and daycare centers reported 24,351 cases of respiratory flu and 30,703 cases of “unknown” flu. These numbers were very similar to those of the 2007-2008 influenza season. Between May 1, 2009 and June 12, 2009, schools and daycares reported an additional 3,683 cases of respiratory flu and 4,258 additional cases of “unknown” flu bringing the total for the season to 28,034 cases of respiratory flu and 34,961 cases of “unknown” flu.

Additional data on the 2008-2009 influenza season can be found at the following link:
Data from the 2008-2009 Influenza Season

This Year

Although it is impossible to predict how this year’s influenza season will compare to last year’s, the Health Department will continue using its three part comprehensive plan that will focus on surveillance, prevention/control of influenza, and public education.

The Epidemiology unit is responsible for conducting effective and timely influenza surveillance in Kent County. This entails collecting, analyzing, interpreting, and disseminating influenza data. Epidemiologists study the frequency, pattern and causes of influenza and influenza outbreaks in the Kent County population. They ask and try to answer the “who, what, when, where, why, and how” questions.

Surveillance

There are three main goals of influenza surveillance:

  1. To provide epidemiologic information during the annual influenza season to measure the development and seriousness of each influenza season;
  2. To monitor changes in circulating viruses;
  3. Provide information regarding the emergence of a new influenza strain
  4. Determine the magnitude of influenza illness in the county in order to guide the actions of county public health officials.

KCHD monitors influenza in several ways:

  1. Physician reports of influenza - Influenza is an officially reportable condition that is required by state law to be reported to the KCHD.
  2. Laboratory reports of influenza - Influenza is also a state mandated reportable disease. Labs are required by law to report confirmed results to the local health department
  3. Infection Control Departments - The KCHD has requested that local hospital Infection Control Departments report confirmed cases of influenza to the KCHD.
  4. Daycares, schools and camps - are required by law to report the weekly total number of cases of influenza to the KCHD.
  5. “Sentinel” providers - physicians who have agreed to report cases of “influenza-like” illness visits by age group, and the total number of “influenza-like” visits per week

The Kent County Health Department also monitors influenza activity at the state, national, and global levels. Information that is collected in Kent County is reported to the state health department. The data is then forwarded on to the CDC.

Data collection, analysis, interpretation, and dissemination

Following the receipt of confirmed cases of influenza from labs, physicians, and hospital infection control departments, the data will be entered into a database. From October through May, surveillance information will be updated weekly. Aggregate data on confirmed cases and school reporting data will be available on the Kent County Health Department’s website. An epidemiologist will analyze and interpret data and determine how the data relates to trends seen at the state and national levels.

Information for Health Care Providers

  • Timely (weekly) surveillance updates will be posted on the Kent County website on the Health Department’s web page.
  • Clinical signs and symptoms of influenza

Conclusion

While no intervention is likely to eradicate influenza, the KCHD’s plan provides a comprehensive methodology for educating and informing the public about the prevention/control of influenza in Kent County. This plan was developed as a tool for guiding individual and community actions in order to reduce the risk of influenza.