DALLAS (CBSDFW.COM) – New reports out this week show the flu rate in Dallas and Denton Counties rising rapidly.

About 24% of flu tests in those counties came back positive the week before Thanksgiving.

Medical experts say those numbers don’t usually appear until much later in the season.

They say it’s hard to predict what an early start to the season means in the long run, but in general it’s not a good sign.

“It’s been associated sometimes with some of our worst seasons in the past, so we don’t know how it’ll play out, but it’s one indicator,” said Dr. Phil Huang, the Director of Dallas County Health and Human Services.

Collin and Tarrant Counties have not released their latest numbers but have also been seeing an increase in recent weeks.

Local health departments are urging people to vaccinate against the virus and take common sense preventive measures like washing your hands.