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2003 - 2004 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.

Year Week Beginning Week Ending Reported Influenza Activity
2004 March 14 March 20 No Activity
2004 March 7 March 13 No Activity
2004 February 29 March 6 No Activity
2004 February 22 February 28 No Activity
2004 February 15 February 21 No Activity
2004 February 8 February 14 Sporadic Activity
2004 February 1 February 7 Sporadic Activity
2004 January 25 January 31 Sporadic Activity
2004 January 18 January 24 Local Activity
2004 January 11 January 17 Local Activity
2004 January 4 January 10 Regional Activity
2004 December 28 January 3 Widespread Activity
2003 December 21 December 27 Widespread Activity
2003 December 14 December 20 Widespread Activity
2003 December 7 December 13 Widespread Activity
2003 November 30 December 6 Regional Activity
2003 November 23 November 29 Local Activity
2003 November 16 November 22 Sporadic Activity
2003 November 9 November 15 Sporadic Activity
2003 November 2 November 8 No Activity
2003 October 26 November 1 No Activity
2003 October 19 October 25 No Activity
2003 October 12 October 18 No Activity
2003 October 5 October 11 No Activity
2003 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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