That's according to a statement issued by the center Friday.
According to the statement, a cluster of six legionella cases has been diagnosed in Penobscot County.
The cases have occurred at a "higher rate than average for the region," the statement said.
The CDC statement maintained that during the past five years, Penobscot County has averaged three legionella cases per year.
The health agency statement stressed the disease is not spread from person to person.
According to the CDC, legionella bacteria are typically found in freshwater lakes and streams.