WASHINGTON — U.S. Sen. Bill Cassidy firmly pushed back Tuesday against a Louisiana state lawmaker for spreading a long-debunked claim about vaccines and autism that health officials have linked to a recent spike in measles cases.

“That’s fake news that’s being said on the Senate floor,” Cassidy, a Baton Rouge Republican who is a medical doctor, said of hearing about state Sen. John Milkovich’s anti-vaccination remarks this week.

Milkovich, D-Shreveport, took to the Senate microphone on Monday during a debate over a bill related to a voluntary immunization database to launch into his broadside about vaccines, suggesting they are dangerous and can cause autism, which Cassidy and other experts say is not true.

“There is a very contentious scientific debate that’s going on right now in America and has been for decades,” Milkovich said. “Many are saying that these vaccinations pose danger.”

“For example, when (I was) growing up autism did not exist,” he continued.

He went on to claim that tissue from aborted fetuses is used to make vaccines and that vaccines contain dangerous neurotoxins.

Cassidy repeatedly dismissed Milkovich’s claims as "fake news" and stressed that vaccinations are safe and responsible.

“As a doctor who has spent my life trying to bring health to the people of Louisiana, I strongly endorse immunizations,” he said. “There is no linkage to autism that has ever been made by a credible scientist.”

The anti-vaccine movement has spread since a now-discredited paper circulated in 1998 purporting a link between the MMR and autism.

Cassidy, who worked in the Louisiana charity hospital system as a hepatologist dealing with disorders in organs such as the liver, gallbladder and pancreas, noted the recent spike in measles outbreaks across the country, as well as other dangers of refusing immunizations.

“There are outbreaks of people with measles because of this fake news regarding measles vaccination,” he said. “I know of patients who have almost had a liver transplant because they didn’t know to get vaccinated for hepatitis B.”

Milkovich has declined to comment further on his remarks. No other state senators spoke out on the issue after Milkovich’s speech. He has made similar claims on the Senate floor in past sessions.

The two-step measles, mumps and rubella vaccine, commonly called the MMR, is estimated to be about 97 percent effective at preventing measles, a highly-contagious viral disease that can lead to death in extreme cases.

Louisiana has not had a confirmed measles case in 2019, but the Centers for Disease Control and Prevention has counted more than 700 individual cases across 22 other states so far this year. It’s the highest tally of cases reported in nearly two decades.

The national spike, which health authorities have attributed largely to the spread of anti-vaccination talking points like those that Milkovich repeated, prompted the Louisiana Department of Health recently to warn doctors to be on alert for the disease in an attempt to prevent a widespread outbreak in the state.

Cassidy described vaccinations as a component to a healthier society that is meant to help vulnerable populations unable to be immunized because of health issues, including children with cancer undergoing chemotherapy.

“If your child was vulnerable, you’d want everyone else to be immunized,” he said.

Follow Elizabeth Crisp on Twitter, @elizabethcrisp.