Legionnaires' disease bacteria have been discovered in hot water systems at a suburban Philadelphia university, but officials say the levels detected are not cause for immediate concern.

West Chester University officials say hot water systems were drained and treated with chlorine in nine buildings where the legionella bacteria was discovered.

Classes start Monday.

After a West Chester employee tested positive for Legionnaires' disease in July, officials discovered higher-than-acceptable levels of the bacteria in cooling towers at eight campus buildings.

Officials say that bacteria has since been treated and eliminated.

Legionnaires' disease is a severe form of pneumonia spread by bacteria commonly found in water supplies. It can't be passed from person to person.

The Chester County Health Department says there's no need to curtail campus activities.