Real-time epidemic monitoring and forecasting of H1N1-2009 using influenza-like illness from general practice and family doctor clinics in Singapore.
BACKGROUND
Reporting of influenza-like illness (ILI) from general practice/family doctor (GPFD) clinics is an accurate indicator of real-time epidemic activity and requires little effort to set up, making it suitable for developing countries currently experiencing the influenza A (H1N1-2009) pandemic or preparing for subsequent epidemic waves.


RESULTS
We established a network of GPFDs in Singapore. Participating GPFDs submitted returns via facsimile or e-mail on their work days using a simple, standard data collection format, capturing: gender; year of birth; "ethnicity"; residential status; body temperature (degrees C); and treatment (antiviral or not); for all cases with a clinical diagnosis of an acute respiratory illness (ARI). The operational definition of ILI in this study was an ARI with fever of 37.8 degrees C or more. The data were processed daily by the study co-ordinator and fed into a stochastic model of disease dynamics, which was refitted daily using particle filtering, with data and forecasts uploaded to a website which could be publicly accessed. Twenty-three GPFD clinics agreed to participate. Data collection started on 2009-06-26 and lasted for the duration of the epidemic. The epidemic appeared to have peaked around 2009-08-03 and the ILI rates had returned to baseline levels by the time of writing.


CONCLUSIONS
This real-time surveillance system is able to show the progress of an epidemic and indicates when the peak is reached. The resulting information can be used to form forecasts, including how soon the epidemic wave will end and when a second wave will appear if at all.
Ong
Jimmy Boon Som
JB
Department of Clinical Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore.
Chen
Mark I-Cheng
MI
Cook
Alex R
AR
Lee
Huey Chyi
HC
Lee
Vernon J
VJ
Lin
Raymond Tzer Pin
RT
Tambyah
Paul Ananth
PA
Goh
Lee Gan
LG
D003625:Data Collection; D058872:Epidemics; D005544:Forecasting; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology*; D010821:Physicians, Family; D011159:Population Surveillance / Q000379:methods*; D012846:Singapore / Q000453:epidemiology