Tuberculosis can be eliminated in California by 2040 under an innovative plan published this month by a committee co-chaired by George Rutherford, MD of UCSF Global Health Sciences (GHS).
The five-year action plan outlines the steps to ensure that California residents with latent tuberculosis infection who are likely to progress to active TB are identified and treated.
While California has had a steady decline in TB cases, about 2.4 million California residents are estimated to be infected with latent TB, and in 2015 2,137 people developed the active disease. Only about 25 percent of those with latent TB are aware they are infected. Focusing on identifying those with latent TB and treating them is an essential step in eliminating the disease, Rutherford said.
Rutherford co-chairs the TB Elimination Advisory Committee, which the California Department of Public Health established in the 1990s when the incidence of TB was growing as a result of the HIV/AIDS epidemic. A professor in the Department of Epidemiology and Biostatistics, he directs the Prevention and Public Health Group in GHS.
The development of several scientific advances over the past few years make it timely to pursue elimination of TB in California, Rutherford said.
First, recent epidemiological studies provide better information on who is most likely to be infected and who is most at risk of developing the disease. In California, 81% of infected individuals are foreign-born residents, with foreign-born Asian Americans (31%) and foreign-born African Americans (25%) having the highest rates of infection. Elderly people, smokers, diabetics, and those with uncontrolled HIV are most at risk of developing active TB. The Elimination Plan recommends testing these higher-risk populations. The U.S. Preventive Services Task Force also recently adopted this recommendation.
Second, a new diagnostic tool – the interferon-gamma release assay (IGRA) — better differentiates true latent TB infection from vaccine-induced immunity, ensuring only those actually at risk of developing active TB get treatment.
Third, a new 12-dose course of treatment that cures latent TB has been developed, which includes weekly oral administration of isoniazid and rifapentine.
“If clinicians screen and test those at risk for latent TB infection and treat those who test positive, it will put a huge dent in the pool of people with latent TB,” Rutherford said. “And that will eventually put a huge dent in the number of active cases.”