(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.
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."
The lawmaker went on to call the vaccine researcher's work "sorcery."
Stickland did not respond to a request for comment.
The American Academy of Pediatrics has stated, "Vaccines are safe. Vaccines are effective. Vaccines save lives."
Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine, has experienced a pattern of harassment for his advocacy. But he said he had not been specifically targeted by a member of the Texas House of Representatives until now.
"That is really astonishing," Hotez said. "I don't know what he was thinking to specifically target a constituent like that. I would have thought there's probably some House ethics rules that prevent you from doing that. It's kind of an abuse of power, in a way."
The number of measles cases reported this year in the United States has climbed to 764, according to the US Centers for Disease Control and Prevention.
Hotez and other public health officials have expressed concern that one of the biggest contributing factors is vaccine exemptions for non-medical reasons.
They've called for stepped-up government intervention.
In 2015, California got rid of religious and philosophic exemptions after a measles outbreak there. The percentage of California kindergarteners with such exemptions dropped from 2.5% during the 2014-15 school year to less than 0.1% during the 2017-18 school year, according to the CDC.
Hotez said Strickland's comments show that the anti-vax movement has become mainstream.
"It is now fully integrated into public life of this country," Hotez said. "It's an example of how pervasive the anti-vaccine movement is right now, and now to try to start dismantling it is going to be really hard work."