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2012 - 2013 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
2013 May 12 May 18 Sporadic Activity
2013 May 5 May 11 Sporadic Activity
2013 April 28 May 4 Sporadic Activity
2013 April 21 April 27 Sporadic Activity
2013 April 14 April 20 Sporadic Activity
2013 April 7 April 13 Local Activity
2013 March 30 April 6 Local Activity
2013 March 24 March 30 Local Activity
2013 March 17 March 23 Local Activity
2013 March 10 March 16 Local Activity
2013 March 3 March 9 Local Activity
2013 February 24 March 2 Regional Activity
2013 February 17 February 23 Regional Activity
2013 February 10 February 16 Regional Activity
2013 February 3 February 9 Widespread Activity
2013 January 27 February 2 Widespread Activity
2013 January 20 January 26 Widespread Activity
2013 January 13 January 19 Widespread Activity
2013 January 6 January 12 Widespread Activity
2012 December 30 January 5 Widespread Activity
2012 December 23 December 29 Widespread Activity
2012 December 16 December 22 Widespread Activity
2012 December 9 December 15 Widespread Activity
2012 December 1 December 8 Regional Activity
2012 November 25 December 1 Regional Activity
2012 November 18 November 24 Local Activity
2012 November 11 November 17 Sporadic Activity
2012 November 3 November 10 No Activity
2012 October 28 November 3 No Activity
2012 October 21 October 27 No Activity
2012 October 13 October 20 No Activity
2012 October 7 October 13 No Activity
2012 September 30 October 6 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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