(CNN) A vaccine researcher in Texas tweeted a map this week that showed an upward trend in vaccine exemptions in the Lone Star State. More and more, parents were opting school-age children out of getting vaccinated.

"Calling on our TX elected leaders to say 'NO MAS' and standup for our children!" the researcher, Dr. Peter Hotez, tweeted, imploring lawmakers do away with exemption laws that are leading to an increase in unvaccinated children.

You are bought and paid for by the biggest special interest in politics. Do our state a favor and mind your own business. Parental rights mean more to us than your self enriching "science." #txlege — Jonathan Stickland (@RepStickland) May 7, 2019

One Texas lawmaker struck back, igniting a Twitter feud.

Texas state Rep. Jonathan Stickland told him, "Do our state a favor and mind your own business. Parental rights mean more to us than your self enriching 'science.' "

Hotez responded, "Wow that's impressive, from a member of the Texas House of Representatives."