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2000 - 2001 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
2001 March 25 March 31 No Activity
2001 March 18 March 24 No Activity
2001 March 11 March 17 No Activity
2001 March 4 March 10 No Activity
2001 February 25 March 3 Sporadic Activity
2001 February 18 February 24 Regional Activity
2001 February 11 February 17 Regional Activity
2001 February 4 February 10 Regional Activity
2001 January 28 February 3 Sporadic Activity
2001 January 21 January 27 Sporadic Activity
2001 January 14 January 20 Sporadic Activity
2001 January 7 January 13 Sporadic Activity
2001 December 31 January 6 Sporadic Activity
2000 December 24 December 30 Sporadic Activity
2000 December 17 December 23 Sporadic Activity
2000 December 10 December 16 No Activity
2000 December 2 December 9 No Activity
2000 November 26 December 1 No Activity
2000 November 19 November 25 No Activity
2000 November 12 November 18 No Activity
2000 November 5 November 11 No Activity
2000 October 29 November 4 No Activity
2000 October 22 October 28 No Activity
2000 October 15 October 21 No Activity
2000 October 8 October 14 No Activity
2000 September 30 October 7 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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