FORT WORTH (CBSDFW.COM) – Whooping cough is making a deadly resurgence in Texas.

In all of 2011, there were 961 reported cases statewide. Through April of this year, though, there have been 424 cases, including one that resulted in the death of a Dallas child.

“Every cough he gets I get scared,” said Jasmine Eagle as she waited to have her toddler immunized on Thursday. “I hope it’s not that serious.”

Unlike some parents, Eagle is having her son immunized against whooping cough, or pertussis.  But a lack of immunizations is causing an unsettling spike in the number of pertussis cases, doctors say.

“It could be it’s on the uptick right now,” said Dr. Jeffery Kahn of Children’s and UT Southwestern. “Certainly we’ve more pertussis at children’s medical center than we did all of last year.”

Children’s Medical Center saw 10 cases all of last year. So far this year they’ve seen 14. And 12 of those cases, including the infant death, were during the past month.

The Tarrant County Health Department has seen fewer cases: 30 through the end of April last year compared to 17 through April of this year.

Denton County’s cases, though, have soared from 14 at this time last year to 30 this year.

Doctors say it’s often the parent who develops whooping cough.

It’s just a nagging cough to the adult. But they may be unknowingly spreading the disease to their children. Even if parents were immunized as children, they should see the doctor again.

“Immunity to pertussis wanes over time and now there’s a recommendation, there has been for a few years now, to immunize adults against pertussis,” said Kahn.

Kahn said doctors recommend a battery of immunizations in infancy, but no child is too old to be immunized.

Here are tips from the state about pertussis: