2002-2003 Texas Influenza Surveillance Activity

Surveillance of the 2002-2003 influenza season in Texas began September 29, 2002 and will be reported weekly to The Centers for Disease Control and Prevention (CDC) through May 17, 2003. Many sources of information are used to determine the level of the state's influenza activity. The Texas Department of State Health Services' Infectious Disease Epidemiology and Surveillance division in cooperation with the DSHS Medical Virology Branch and the Baylor College of Medicine monitor influenza around the state. Additionally, other laboratories, regional and local health departments, facilities participating in influenza research, the CDC Sentinel Physician Surveillance Network, and private physicians participate in flu surveillance.

The first influenza identified in the state was the B/Hong Kong/330/2001-like virus, collected 11/1/02 in San Antonio. As of 5/31/03, the last influenza isolate identified was the A/Panama/2007/99 (H3N2)-like virus, collected 5/23/03 in Amarillo. The overall dominant strain identified in Texas was the flu B/Hong Kong-like virus. Because of school-aged children's susceptibility to this strain, flu B had a significant and unique impact this season. Initial reports of children with influenza-like illness (ILI) causing school closures began early in the season in northeast Texas and continued throughout the state the rest of the season. The number of school closures due to children with ILI was unprecedented and involved over 90 school district/campus closures in 68 counties. The last reported closure was in early March. Influenza A also circulated this season as expected. The dominant flu A strain identified was the A/New Caledonia/20/99 (H1N1)-like virus. The other flu A strain was the A/Panama/2007/99 (H3N2)-like virus, which was identified more often after late February. Influenza activity peaked the last week of January 2003. From 9/29/02 to 5/31/03, influenza has been identified in 77 counties throughout Texas.

The types of influenza identified in Texas this season were:
A/New Caledonia/20/99 (H1N1)-like, A/Panama/2007/99 (H3N2)-like, B/Hong Kong/330/2001-like, and B/Sichuan/379/99-like viruses. All of these strains, except B/Sichuan, were a good match for this season's flu vaccine. Only one isolate of B/Sichuan-like virus was identified.