AUSTIN (Nexstar) — Texas travel hubs are most susceptible to the measles outbreak, according to a University of Texas research team.

Sahotra Sarkar, a philosophy and integrated biology professor at UT Austin, led the project, which started as a look at the spread of the Zika virus. The team transferred the model to measles about 6 months ago.

“What we were trying to do was estimate the relative risk of measles in various counties in the United States, where relative risk means: what would happen, how many cases would you see if the virus happens to be imported,” Sarkar said.

The research found two main factors: vaccine refusal rates, and the number of travelers from other countries.

“Right now those areas happen to be places like India, China, Ukraine, Philippines,” Sarkar explained.

The research revealed three Texas counties in the top 25 most at-risk for measles to spread. Harris, Tarrant, and Travis counties all have major cities, Houston, Dallas/Fort Worth, and Austin respectively, and each of those cities are home to international airports, which Sarkar said contributes to a higher risk.

“In the Houston metropolitan area and the Dallas metropolitan area, high travel volume at the airports, high local populations because there’s large cities, along with vaccine refusal rates are creating the risk.,” he said.

“The other place where we see a higher amount of risk is Austin, and even though we have a fair amount of international travel because of the university and because of the Hill country, really it has been driven almost entirely by the non-medical exemptions.”

The latest numbers from the Texas Department of State Health Services indicate 15 people with the measles in Texas. Nationally, nearly half of all states have reported a confirmed case this year. The Centers for Disease Control reports more than 760 people have come down with measles in 2019.

State lawmakers have addressed immunization in different ways this legislative session.

“Our diversity is so huge in this state. We travel, we’ve got people in, I can name in my district, we got a huge Korean population, Pakistani, Indian, Mexican, you name all of it,” State Rep. Michelle Beckley, D-Carrollton, said.

Beckley tacked funding on to the state budget to compile data on vaccination rates in child-care facilities and licensed family homes. Other lawmakers are more focused on patient education about vaccines.

“People ought to be able to look at here’s the risk and here are the benefits,” State Rep. Bill Zedler, R-Arlington, said. “And they need to look at the medical literature.”

Cook County, Illinois, home to the city of Chicago, topped the list for the most at-risk for an outbreak, based on the research criteria.

Note: This article has been updated throughout.