Evaluation of alternative respiratory syndromes for specific syndromic surveillance of influenza and respiratory syncytial virus: a time series analysis.
BACKGROUND
Syndromic surveillance is increasingly being evaluated for its potential for early warning of increased disease activity in the population. However, interpretation is hampered by the difficulty of attributing a causative pathogen. We described the temporal relationship between laboratory counts of influenza and respiratory syncytial virus (RSV) detection and alternative groupings of Emergency Department (ED) respiratory diagnoses.


METHODS
ED and laboratory data were obtained for the south-eastern area of Sydney, NSW for the period 1 June 2001 - 1 December 2006. Counts of ED visits and laboratory confirmed positive RSV and influenza cases were aggregated by week. Semi-parametric generalized additive models (GAM) were used to determine the association between the incidence of RSV and influenza and the incidence of respiratory syndrome ED presentations while controlling for temporal confounders.


RESULTS
For every additional RSV laboratory count, ED diagnoses of bronchiolitis increased by 3.1% (95%CI: 2.7%-3.5%) in the same week. For every additional influenza laboratory count, ED diagnoses of influenza-like illness increased by 4.7% (95%CI: 4.2%-5.2%) one week earlier.


CONCLUSIONS
In this study, large increases in ED diagnoses of bronchiolitis and influenza-like illness were independent and proxy indicators for RSV and influenza activity, respectively.
Schindeler
Suzanne K
SK
Centre for Epidemiology and Research, New South Wales Department of Health, North Sydney, Australia. sschi@doh.health.nsw.gov.au
Muscatello
David J
DJ
Ferson
Mark J
MJ
Rogers
Kris D
KD
Grant
Paul
P
Churches
Tim
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D001988:Bronchiolitis / Q000453:epidemiology* / Q000821:virology; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology*; D008875:Middle Aged; D015233:Models, Statistical; D009517:New South Wales / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods*; D040442:Public Health Informatics; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology*; D012136:Respiratory Syncytial Viruses / Q000302:isolation & purification; D013997:Time Factors; D055815:Young Adult