Researchers at the University of Texas at Austin and Johns Hopkins University have compiled the U.S. counties most at risk for measles — and Tarrant County is among them.

The new study, released May 9, identified the 25 U.S. counties most at-risk for a measles outbreak, based on "the area’s volume of international travel from foreign countries with large measles outbreaks and the prevalence of nonmedical exemptions from childhood vaccinations."

Measles is a highly contagious viral infection that can spread by coughing or sneezing, according to the Centers for Disease Control. "Measles is so contagious that if one person has it, up to 90 percent of the people close to that person who are not immune will also become infected," according to the CDC website.

Tarrant County ranked No. 12 in the new report, with a relative risk rate of .0048 in 2019. Considering measles was declared eradicated in the U.S. in 2000, any risk rate is considered worrisome. The first case of measles in Tarrant County since 2015 was reported this spring. A case was also confirmed in Denton County.

Though the CDC warns that measles can affect any age group, children under 5 years old are most susceptible.

"For the first time since the 1980s, we may expect infant deaths from measles in the U.S.,” said the study’s lead author, Sahotra Sarkar, a philosophy and integrative biology professor at UT Austin, in a release.

The study originally was published in The Lancet Infectious Diseases, a medical journal.

Overall, Texas has three counties in the top 25, with Harris (No. 9) and Travis (No. 22) joining Tarrant. Harris, which includes Houston, has had four cases of measles so far this year, the most in Texas.

"Harris, Texas has had the biggest outbreak so far with four cases and is ranked ninth in our predictions," the study says. "Another seven counties in Texas have reported cases, which are all in close proximity to either Tarrant, Texas (ranked 12th) or Travis, Texas (ranked 22nd)."

Dallas County is not on the list.

The report was published amid an alarming measles outbreak. In a May 13 article, the New York Times reported that 800 cases had been reported nationwide in 2019. Brooklyn and Rockland, New York; Oakland, Michigan; and Clark County, Washington, located in southern part of the state, were among the hardest hit.

Sarkar and his co-authors also warned that measles isn't the only disease poised to reappear after eradication. "The vaccine avoidance problem is not limited to measles. Pertussis — whooping cough — is another disease making a comeback because of dropping vaccination rates, and we predict serious outbreaks in the U.S. in the near future,” said Sarkar.

Researchers say they hope the report ultimately serves as an alarm for government officials. “Policymakers must focus on centers of vaccination refusal as well as regions with a lot of passenger inflow from affected countries worldwide if there are even small local pockets of unvaccinated people," Sarkar said.