Tuberculosis cases in Los Angeles County rose 7% last year, public health officials reported Thursday.
The increase, from 625 in 2012 to 666 in 2013, occurred "mainly among the homeless," Department of Public Health Director Dr. Jonathan Fielding wrote to the county Board of Supervisors.
The potentially deadly disease, which attacks the lungs, has been spreading among the county's homeless since 2007. In 2012, officials reported 39 cases of tuberculosis among homeless Angelenos; in 2013, there were 65 cases.
Last year, concerns about the illness — "the largest outbreak in a decade," Fielding said at the time — led to a coordinated effort between the U.S. Centers for Disease Control and Prevention, county health staff and shelter workers to seek out and treat infected homeless people, as well as more then 4,600 others who came in contact with them and also may have been exposed to the disease.
The bacteria that cause tuberculosis can spread through the air in the droplets created when an infected person coughs, sneezes or laughs. The bacteria can live for decades in a person's body without sickening them — a condition known as latent TB infection — only to become active later. Active TB disease causes illness and can spread from person to person. Left untreated, it can be fatal.
Fielding's letter to the supervisors described the ongoing effort to combat tuberculosis in the homeless population but noted that the group "poses challenges for TB control" because homeless people move about often; live in crowded conditions; and have concurrent medical, mental health and nutritional issues that make them more susceptible to developing active TB disease.
Fielding wrote that the 65 cases reported among Los Angeles' homeless, "while important...do not represent a threat to the general population."
Most of the county's tuberculosis cases — 79% — occurred in foreign-born people who carried their infections with them when they immigrated to the U.S. Thursday's update did not include new statistics on TB deaths. In February, The Times reported that 11 people had died in the skid row outbreak since 2007.
Also on Thursday, the CDC released its own report on tuberculosis trends for 2013. Nationwide, cases of the deadly disease were down 4.2%, but four states — California, Texas, New York and Florida — accounted for half of the TB cases reported in 2013.
In their report, CDC researchers wrote that TB rates among homeless people nationwide were estimated to be 36 to 47 per 100,000 population: about 10 times greater than overall TB incidence during that period.