An outbreak of tuberculosis in the Kansas City area has grown into one of the largest ever recorded in the United States, with dozens of active cases of the infectious disease reported, according to health officials.

A yearlong outbreak of tuberculosis in the Kansas City, Kansas area has taken local experts aback, even if it does not appear to be the largest outbreak of the disease in U.S. history as a state health official claimed last week.

Kansas is currently experiencing a rare outbreak of tuberculosis (TB), the world’s deadliest infectious disease. TB is spread via germs in the air and usually affects the lungs but can also affect the brain, the kidneys or the spine.