Pontiac fever is an acute, nonfatal respiratory disease caused by various species of Gram-negative bacteria in the genus Legionella.

The first outbreak caused by inhalation of aerosolized potting soil was discovered in New Zealand in January 2007.

In 1968, several workers at the county's department of health came down with a fever and mild flu symptoms, but not pneumonia.

After the 1976 Legionnaires' outbreak in Philadelphia, the Michigan health department re-examined blood samples and discovered the workers had been infected with the newly identified Legionella pneumophila.

The New Zealand outbreak also marked the first time Pontiac fever had been traced to potting soil.