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2008 - 2009 Flu Activity Report

While influenza is not a reportable disease in Illinois, the Illinois Department of Public Health examines reports from many health care sites throughout the state. These sites include physician offices, emergency departments and nursing homes that report acute illness, and schools that report absenteeism rates. Accordingly, the Department monitors disease trends and influenza activities as they occur on a weekly basis.

A detailed surveillance report for each week can be viewed by clicking on the desired week in the table below. This weekly surveillance report summarizes regional and state influenza data used to determine the weekly influenza activity level and national activity levels reported by state and territorial epidemiologists.

Year Week Beginning Week Ending Reported Influenza Activity
2009 - 2010 Flu Activity Report
2009 August 23 August 29 Sporadic Activity
2009 August 16 August 22 Sporadic Activity
2009 August 9 August 15 Sporadic Activity
2009 August 2 August 8 Sporadic Activity
2009 July 26 August 1 Sporadic Activity
2009 July 19 July 25 Sporadic Activity
2009 July 12 July 18 Local Activity
2009 July 5 July 11 Local Activity
2009 June 28 July 4 Regional Activity
2009 June 21 June 27 Regional Activity
2009 June 14 June 20 Regional Activity
2009 June 7 June 13 Regional Activity
2009 May 31 June 6 Regional Activity
2009 May 24 May 30 Regional Activity
2009 May 17 May 23 Regional Activity
2009 May 10 May 16 Regional Activity
2009 May 3 May 9 Local Activity
2009 April 26 May 2 Sporadic Activity
2009 April 19 April 25 Sporadic Activity
2009 April 12 April 18 Sporadic Activity
2009 April 5 April 11 Sporadic Activity
2009 March 29 April 4 Local Activity
2009 March 22 March 28 Local Activity
2009 March 15 March 21 Local Activity
2009 March 8 March 14 Regional Activity
2009 March 1 March 7 Regional Activity
2009 February 22 February 28 Regional Activity
2009 February 15 February 21 Local Activity
2009 February 8 February 14 Sporadic Activity
2009 February 1 February 7 Local Activity
2009 January 25 January 31 Regional Activity
2009 January 18 January 24 Local Activity
2009 January 11 January 17 Local Activity
2009 January 4 January 10 Local Activity
2008 December 28 January 3 Sporadic Activity
2008 December 21 December 27 Local Activity
2008 December 14 December 20 Local Activity
2008 December 7 December 13 Sporadic Activity
2008 November 30 December 6 Sporadic Activity
2008 November 23 November 29 No Activity
2008 November 16 November 22 No Activity
2008 November 9 November 15 Sporadic Activity
2008 November 2 November 8 Sporadic Activity
2008 October 26 November 1 Sporadic Activity
2008 October 19 October 25 No Activity
2008 October 12 October 18 No Activity
2008 October 5 October 11 No Activity
2008 September 28 October 4 No Activity

No Activity No lab confirmed cases †
Sporadic Activity Isolated lab-confirmed cases OR Lab confirmed outbreak in one institution ‡
Local Activity Recent (within the past 3 weeks) lab evidence of influenza in region with increased ILI* OR Recent (within the past 3 weeks) lab evidence of influenza in region with the outbreaks; virus activity is no greater than sporadic in other regions**
Regional Activity Increased ILI* in >2 but less than half of the regions AND recent (within the past 3 weeks) lab confirmed influenza in the affected regions. OR Institutional outbreaks (ILI or lab confirmed) in >2 and less than half of the regions AND recent lab confirmed influenza in the affected regions**. A region is defined as the regions States use for public health purposes.
Widespread Activity Increased ILI* and/or institutional outbreaks (ILI* or lab confirmed) in at least half of the regions** AND recent (within the past 3 weeks) lab confirmed influenza in the state.

*ILI activity can be assessed using a variety of data sources including sentinel providers, school/workplace absenteeism, and other syndromic surveillance systems that monitor influenza-like illness.
Lab confirmed case=case confirmed by rapid diagnostic test, antigen detection, culture, or PCR. Care should be given when relying on results of point of care rapid diagnostic test kits during times when influenza is not circulating widely. The sensitivity and specificity of these tests vary and the predicative value positive may be low outside the time of peak influenza activity. Therefore, a state may wish to obtain laboratory confirmation of influenza by testing methods other than point of care rapid tests for reporting the first laboratory confirmed case of influenza of the season.
Institution includes nursing home, hospital, prison, school, etc.
** Region: population under surveillance in a defined geographical subdivision of a state. A region could be comprised of 1 or more counties and would be based on each state's specific circumstances. Depending on the size of the state, the number of regions could range from 2 to approximately 12. The definition of regions would be left to the state but existing state health districts could be used in many states. Allowing states to define regions would avoid somewhat arbitrary county lines and allow states to make divisions that make sense based on geographic population clusters. Focusing on regions larger than counties would also improve the likelihood that data needed for estimating activity would be available.

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535 West Jefferson Street • Springfield, Illinois 62761 • Phone 217-782-4977 • Fax 217-782-3987 • TTY 800-547-0466
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