Evaluation of a syndromic surveillance system using the WSARE algorithm for early detection of an unusual, localized summer outbreak of influenza B: implications for bioterrorism surveillance.
BACKGROUND
Syndromic surveillance systems have been developed for early detection of bioterrorist attacks, but few validation studies exist for these systems and their efficacy has been questioned.


OBJECTIVE
To assess the capabilities of a syndromic surveillance system based on community clinics in conjunction with the WSARE algorithm in identifying early signals of a localized unusual influenza outbreak.


METHODS
This retrospective study used data on a documented influenza B outbreak in an elementary school in central Israel. The WSARE algorithm for anomalous pattern detection was applied to individual records of daily patient visits to clinics of one of the four health management organizations in the country.


RESULTS
Two successive significant anomalies were detected in the HMO's data set that could signal the influenza outbreak. If data were available for analysis in real time, the first anomaly could be detected on day 3 of the outbreak, 1 day after the school principal reported the outbreak to the public health authorities.


CONCLUSIONS
Early detection is difficult in this type of fast-developing institutionalized outbreak. However, the information derived from WSARE could help define the outbreak in terms of time, place and the population at risk.
Kaufman
Zalman
Z
Israel Center for Disease Control, Ministry of Health, Tel Hashomer, Israel. zalman.k@icdc.health.gov.il
Wong
Weng-Keen
WK
Peled-Leviatan
Tamar
T
Cohen
Erica
E
Lavy
Chana
C
Aharonowitz
Gali
G
Dichtiar
Rita
R
Bromberg
Michal
M
Havkin
Ofra
O
Kokia
Ehud
E
Green
Manfred S
MS
D000293:Adolescent; D000465:Algorithms; D023482:Bioterrorism / Q000517:prevention & control*; D002648:Child; D004196:Disease Outbreaks; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D009981:Influenza B virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology*; D007557:Israel; D008297:Male; D012189:Retrospective Studies; D018571:Sentinel Surveillance