A measles outbreak in Texas that has affected 25 people has been traced to a church led by the daughter of televangelist Kenneth Copeland, USA Today reported.

Terri Pearsons, pastor of the Eagle Mountain International Church in Newark, Texas, had been critical of the vaccinations. Now the virus has spread to people whose ages range from four months to 44 years old.

At least 12 of the infected have not been vaccinated, which is usually administered to babies after turning a year old. Tarrant County Public Health spokesman Al Roy said some were not fully immunized and most had no record of immunization.

Roy also said the outbreak was started by a visitor to the church who had traveled to a country where measles is common.

"This is a classic example of how measles is being reintroduced," said William Schaffner, an infectious disease expert and professor at the Vanderbilt University School of Medicine in Nashville.

At least 135 instances of the measles have been reported in the U.S. this year as the once-common disease is making its resurgence. At one point when the measles were common, the illness killed as many as 500 Americans per year. For a long time, the U.S. only experienced "imported" instances of the measles, meaning they came from people traveled out of the country.

Despite vaccination rates remaining high for many years, there are still pockets of parents who will not immunize their children and, in those communities, a measles outbreak is most likely.

"The concerns we have had are primarily with very young children who have family history of autism and with bundling too many immunizations at one time," Pearsons said in a statement Aug. 15.

Pearsons also recommended to her congregants they take vitamin D to help strengthen their immune systems, but Schaffner said no vitamins or supplements are known to fight measles. He also said children are more susceptible to measles because their small throats can swell shut more easily.

"Our children and even adults of all ages need to be immunized now to stop the spread of measles and prevent those potential complications," Pearsons said. "The disease is only shut down when all are immunized."