Alberta Health Services reported Friday that six confirmed cases of legionnaires' disease have been found in the Calgary region.

AHS said the cases were reported between Nov. 27 and Dec.1.

Six people, between the ages of 51 and 78, were hospitalized after experiencing a serious respiratory illness.

AHS is now investigating to determine where they could have come in contact with the Legionella bacteria.

So far the investigation has found all six people live or work within a 16 kilometre radius in southwest Calgary.

No risk to public

AHS says the bacteria are not transmitted person-to-person, so the six cases do not present a risk to the general public.

"Although the risk of contracting legionnaires' disease is generally considered to be very low, this recent cluster of illness is unusual, particularly at this time of year," said Dr. Judy MacDonald, medical officer of health for the Calgary zone.

Infectious disease specialist Dr. John Conly said the bacteria is most commonly found in water and spread when that water becomes an aerosol, which allows a person to breathe it in.

Since 2004, 39 cases of legionnaires' disease have been confirmed in the Calgary region.