School Surveillance Active, Passive or Combination By: Beverly Billard

Objective  To evaluate if school surveillance reflects the degree and timing of influenza illness activity in the community  To evaluate the effectiveness of three different school surveillance models in Nova Scotia

Background  Surveillance of absenteeism among school students and staff can be used to detect early disease activity in the wider community.  The Nova Scotia Health Protection Act requires that all schools with greater than 10% absenteeism report to public health.

Background  7 districts (348 schools) employed passive surveillance  2 districts (86 schools) employed active surveillance  In 2008, 2 districts changed to a combined model with 15 schools participating in active surveillance and remaining schools were under passive surveillance.

9 Districts

Population Distribution 5-19 Years Nova Scotia RegionShare of Population 5-19 Years Annapolis Valley20.3% Cape Breton20.8% Capital District Health Authority19.3% Colchester21% Cumberland18.7% Pictou20% South Shore18.1% Southwest19.1% Guysborough-Antigonish21.3% Regions employing active surveillance model Source: Nova Scotia Community Counts Website

Methods  School outbreak reports for 2005 to 2008 were correlated with influenza-like illness reported by sentinel physicians  to determine if school outbreaks are a good indicator of influenza like illness activity in the community  Number of school outbreaks were compared from 2005 to 2008 for 6 regions of the province  compared 3 different surveillance models to determine which model is most effective

Results Outbreaks – Week 2, 5-10, 16Outbreaks – Week 7-10, 12Outbreaks – Week 3-9Outbreaks – Week 2, 9, 14-17

Results- Active, Passive or Combined Surveillance Method P-value Active 85 schools 3 years data Passive 394 schools 4 years data Combined 85 schools 1 year data Mean % of schools reporting outbreaks Not statistically significant

Limitations Absenteeism assessment subjective –determine potential cause(s) of absenteeism. Number of sentinel physician reporting varies weekly Self reported illness for school absenteeism Variance in districts reporting outbreaks –some regions are not reporting school outbreaks

Conclusions  School absenteeism is a valuable predictor of influenza activity in the community  Passive and active surveillance, and a combination model detected an equal number of outbreaks.  3 systems equally effective  Building partnerships and ongoing development with schools, school boards and public health staff are critical in success of a school surveillance system.  With limited public health resources, local public health will be encouraged to employ a passive school surveillance model for the season.

Acknowledgements  Dr. Shelly Sarwal, Medical Officer of Health  Nova Scotia Health Promotion & Protection Surveillance Team  Nova Scotia District Health Authorities

Thank you!