Tuberculosis (TB) rates in the United States reached a record low in 2012, with fewer than 10,000 cases reported, even as the global threat of drug-resistant TB rises. About one-third of the world’s population is infected with the bacteria that cause TB, and almost 4 percent of those newly infected globally are resistant to multiple drugs, indicating that resistant forms of the disease were being transmitted directly from person to person, the World Health Organization (WHO) said this week. Doctor Kenneth Castro, the director of the TB-elimination division at the U.S. Centers for Disease Control and Prevention (CDC), said the global threat of TB underscores the need for the United States to remain vigilant in combatting the disease. “As long as TB remains a global problem and we share the air we breathe, we will see opportunities for importation as well as transmission in this country.