Cases of tuberculosis are rising again in the United States, marking a reversal after decades of decline. The disease, one of the world’s deadliest infectious killers, regained its position as the leading cause of death from an infectious agent in 2023, after briefly being surpassed by COVID-19 during the pandemic.
In the US, infections have been increasing since 2020, with provisional data from the Centers for Disease Control and Prevention reporting more than 10,000 cases in 2025.
Health experts warn that the real number could be higher, as symptoms are often mistaken for common illnesses such as the flu, delaying diagnosis and treatment. This lag not only allows the disease to spread more easily, but also raises concerns about growing antibiotic resistance.
Indeed, these old diseases are making a comeback. Last year, the United States experienced a measles outbreak, and the spread of hepatitis among young children worldwide has been so severe that some have lost their lives.
Click through to see which diseases are making a concerning return.