Real-Time Prediction of West Nile Virus Neuroinvasive Disease Case Counts Accounting for Reporting Delays


Brad Biggerstaff, Centers for Disease Control and Prevention

Monday, 03 November 2003

4:10 PM

E202 Engineering Building


West Nile virus (WNV) epidemics have occurred in the US since it was first recognized in the Western Hemisphere in an outbreak in Queens, New York, in 1999. The 2002 WNV epidemic was the largest WNV outbreak on record, and the largest arbovirus outbreak recorded in the US. With the spread of the virus westward across the US, there was every indication that a large outbreak was again possible in 2003. Routine surveillance for WNV illness on the national level has been in place since 2002, and epidemiologists with the Centers for Disease Control and Prevention (CDC) regularly track the epidemic using daily updated

WNV case counts, reported to the CDC from state health departments. There are naturally delays from the time a person takes ill from a WNV infection and the time that such illness is reported to CDC. With the 2003 epidemic, we augmented the existing surveillance case tally to account for such reporting delays. The nonparametric methods of Lawless (1994) and Kalbfleisch and Lawless (1989) were used to provide daily adjustments to the case counts. The methodology and

application are presented, along with some description of the reporting delay distributions observed during the 2002 and 2003 epidemics. Additionally, real-time comparison of the national 2003 outbreak with the one in 2002 is made using the reporting delay-adjusted predictions. Finally, the utility of the approach is discussed, and planned extensions to the current implementation are outlined.


Joint work with Alicia Johnson


Refreshments will be served at 3:45 p.m. in Room 008 of the Statistics Building






College of Natural Sciences




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