FORT WORTH — A 10th case of measles has been confirmed in Tarrant County, a health department spokesman said Monday.Cases involved both children and adults ranging in age from 1 year to 44 years. Three of the infected people have since recovered, according to the health department’s website, said Al Roy, spokesman for Tarrant County Public Health.Disease exerts have traced some of the area’s measles cases to an adult who had traveled outside the U.S., the agency said. Further details about the person and where he or she traveled were not immediately released.Texas health officials have issued a measles alert and are urging people to be immunized after more than a dozen cases were reported this year.Last week, the Texas Department of State Health Services said Texas had 11 confirmed cases so far this year, based on figures as of Friday.Six in the last week were in Tarrant County, the department said, but county Public Health officials in Fort Worth later updated that number Monday to report a total of 10 cases.Dallas and Denton counties each reported two measles cases, Harris County has one.Agency officials say Texas had six reported cases of measles in 2011, but no cases were reported in 2012.State health officials are asking health care providers to watch for potential exposures and patients with measles symptoms, especially in North Texas, the agency said in a statement. Measles can be spread by contact with an infected person through coughing and sneezing.People should check their immunization status with their health care provider, the agency said. Staff writers Susan Schrock and Bill Miller contributed to this report, which includes material from The Associated Press.