A total of 23 deaths linked to Legionnaires' disease have been reported from Poland as of Sept. 11, the World Health Organization said on Thursday.
A total of 166 cases of the disease have been reported, WHO said, adding that no new cases have been reported since Sept. 7.
Legionnaires' disease, caused by the legionella bacteria, can result in a severe form of pneumonia. The most common form of transmission is inhalation of contaminated aerosols produced in conjunction with water sprays, jets or mists of contaminated water sources, according to WHO.
In August, authorities said Poland's domestic security agency was investigating whether an outbreak of Legionnaires' disease might be the result of intentional tampering with the water system.
The infection source has not yet been identified and investigations are still ongoing to find the source of the outbreak, WHO said.