Tuberculosis cases rose over 9% in 2021 after dropping in 2020, CDC says

• But the increase the following year is likely driven by people who had symptoms in 2020 but weren't diagnosed until 2021, the CDC researchers said.

By the numbers: In 2021, a total of 7,860 cases were reported to the CDC, 687 more than the 7,173 cases reported in 2020.

• California reported the highest number of cases, while Alaska reported the highest incidence.
• Diagnoses in 2021 remained roughly 13% lower than in years prior to the pandemic.

What they're saying: The continued, substantial reduction from pre-pandemic levels "raises concern for ongoing underdiagnosis," the CDC researchers said.

• "TB control and prevention services, including early diagnosis and complete treatment of TB and latent TB infection, should be maintained and TB awareness promoted to achieve elimination in the United States."
• "Timely evaluation and treatment of TB and latent tuberculosis infection remain critical to achieving U.S. TB elimination," they added.
• "A delayed or missed TB diagnosis leads to TB disease progression and can result in hospitalization or death, and the risk of transmitting TB to others," Philip LoBue, director of CDC’s Division of Tuberculosis Elimination, said in a statement. "The nation must ensure that health care providers understand how to diagnose and distinguish TB disease from potential cases of COVID-19."

Why it matters: A person becomes infected when TB bacteria settle in the lungs and begin to grow, per the CDC. The bacteria, which is spread through the air, can then travel through the blood to other parts of the body such as the spine and brain.

• Before the pandemic, tuberculosis case rates had steadily declined an average of 1%-2% every year.

The big picture: 10 million people contract tuberculosis every year, according to the World Health Organization.

• 1.5 million people die from the disease every year, making it the world's top infectious killer.