Varicella Surveillance in Texas

Learning Objectives for this Presentation:
By the end of the presentation the participant will be able to describe the surveillance acitivities in Texas, the epidemiology of varicella in Texas, and understand the challenges to overcome in implementing case-based surveillance for varicella.

Background:
Surveillance for varicella in Texas has evolved over the years; beginning with simple case counts in 1972, aggregate reporting by age in 1999, and finally to named reporting in 2001. For most vaccine-preventable diseases, a dramatic decline is seen in cases after the introduction of the vaccine, this was not occurring with varicella.

Setting:
Population-based surveillance for the state of Texas.

Population:
The overall incidence rate (cases per 100,000 population) in 1993 was 79.3 compared to 50.2 in 2006. Analysis of the data from 2002 to 2006 by age group reveals that the majority of cases were occurring among the 5 to 9 year age group and that the majority of these cases had received one dose of vaccine.

Project Description:
With the changing epidemiology of varicella and the introduction of the vaccine, along with a school requirement for vaccination, it was determined that case-based surveillance was needed to conduct descriptive statistics of cases. The Texas Administrative Code was amended to collect name, date of birth, address, disease onset, vaccination history, race/ethnicity, and sex. From 2002 through 2004, the NETSS system was used to report the cases to CDC. In 2005, the state incorporated the NEDSS-base system (NBS) for disease surveillance.

Results/Lessons Learned:
Case-based surveillance provides us with the necessary information to describe the epidemiology of varicella in Texas. With the use of the NBS, it has allowed for the burden of data entry to be shared among the local, regional and state health departments. Case-based surveillance for varicella is feasible and is needed to determine the effectiveness of the vaccination program.