California reported 2,100 cases of active tuberculosis (TB) in 2023, a 15% jump from the previous year. Most of the cases involved people with 'latent' infections that became active, causing them to get sick and become infectious to others. The California Department of Public Health (CDPH) issued an advisory flagging this 'substantial increase' in active TB, although the department noted that the uptick represents a return to pre-pandemic numbers.