Pulmonary Nontuberculous Mycobacterial Disease, Ontario, Canada, 1998-2010

We measured the prevalence and temporal trends of pulmonary nontuberculous mycobacterial disease among residents of Ontario, Canada, during 1998-2010. Five-year prevalence increased from 29.3 cases/100,000 persons in 1998-2002 to 41.3/100,000 in 2006-2010 (p<0.0001). Improved laboratory methods did not explain this increase, suggesting a surge in disease prevalence.