Legionnaires' disease has become more than six times more common in the United States since 1999, and a new peer-reviewed analysis argues that most people catch it somewhere other than a cooling tower.
The study, published in PLOS Global Public Health, tracked 98,212 reported cases from 1999 through 2021. Before the pandemic, age-adjusted incidence rose 6.6-fold, from 0.40 per 100,000 people in 1999 to 2.37 in 2019, with a peak of 2.69 in 2018. Annual totals had held near 1,200 through the 1980s and 1990s. The 2018 peak year produced 9,933 reported cases.
