World TB Day 2023 is a reminder that TB is a global and local problem

By: Masa Narita, MD, King County TB Control Officer

As much as a fourth of the world’s population is estimated to be infected by the tuberculosis bacterium. The vast majority are latent, inactive infections, meaning the bacteria is dormant or “asleep” in people’s bodies. But latent TB infection (LBTI) can progress to active tuberculosis (TB): In 2021, among an estimated 1.7 billion people who are infected with TB bacteria, 10.6 million people developed active TB, and 1.6 million people died of the disease globally.

On World TB Day, March 24, 2023, it is important to remember that TB is not just a problem overseas. In King County there are an estimated 100,000 people with LTBI, and there were 111 cases of active TB in 2022. The majority of active TB cases progressed from folks with LTBI who acquired it years ago. These cases could have been prevented if people with LTBI were identified and treated.

Recent trends

In King County, the case count average between 2014 and 2018 was 98 cases per year. Case reports jumped to 132 cases in 2019 but then decreased during the COVID pandemic in 2020 and 2021.  In 2021 and 2022 the case counts were above the 2014-2018 average, which is concerning. 

bar graph showing TB count and case rate from 1993 to 2022.

Treating latent TB infection is important

In addition to caring for patients with active TB and people who were exposed to infectious TB, it is crucial to address latent TB infection. Without tackling LTBI, it will be impossible to bring King County active TB case numbers down from the current level, which is approximately 45 cases per million people. Experts believe that there needs to be fewer than one case per million people to eliminate the disease.

The current situation leaves far too many people every year dealing with the isolation, complex medical treatment, and potentially serious health outcomes that come with active TB disease. Nearly all TB cases could be prevented by testing people at higher risk for LTBI and treating them when a diagnosis is made.

Latent TB infection is treatable

Treatment prevents progression to active TB. On this World TB Day, our message is especially important for anyone who was born or lived in a country where TB is common. TB is common most places in the world except the United States, Canada, western Europe, Australia and New Zealand.  As this blog indicates, latent TB is not uncommon in King County. With that in mind, talk to your healthcare provider about whether LTBI testing, and treatment is right for you.

For more information visit or contact the TB program at 

Originally published on March 24, 2023