Claire Z. Cardona of The Dallas Morning News reports a record number of people in Dallas County have been sickened from an infection caused by consuming unpasteurized cheese, health officials said. 

There have been 13 brucellosis infections in residents so far this year, affecting patients between 6 and 80 years old, according to a health advisory released Thursday. 

All of the patients reported eating the cheese brought into the U.S. from Mexico by friends or relatives, consuming the cheese while traveling in Mexico or eating unidentified cheese products from local street vendors, officials said. 

The county typically sees two to six cases a year, though 11 were recorded in 2004. 

Health officials confirmed all the Dallas County cases by blood culture. In two instances, hospital lab personnel were exposed while handling the samples. 

The Brucella bacteria can infect livestock and is most commonly transmitted to humans who consume the unpasteurized dairy products. Some areas, such as Mexico and Central and South America, are considered high-risk, according to the Centers for Disease Control and Prevention.