Seven dead due to Legionnaires' disease outbreak. ABW is checking water systems for sabotage

The bacteria that causes the illness has been found in 113 patients hospitalised in Rzeszów and the surrounding area, health authorities said. The seven people who have died were aged 64 to 95 and had other health conditions.

The deputy coordinator of special services, Stanisław Żaryn, told PAP news agency that the Internal Security Agency was investigating the outbreak to rule out some intentional activity.

Although he described this as routine, he said various scenarios needed to be checked. This included ruling out any possible involvement by Russia, he said.

Earlier on Friday, private radio RMF reported that Internal Security Agency (ABW) officers were checking local water systems and that so far they had found no grounds to suspect sabotage.

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 the World Health Organisation (WHO).

Rzeszów Mayor Konrad Fijołek said on Thursday that authorities were testing water samples for legionella and that the results would be known on Monday.

Meanwhile, the city was increasing the levels of chlorine, UV rays and ozone used for water treatment to the maximum. The water system will also be rinsed and disinfected, he said.