The latest fatality is a 79-year-old local woman who also suffered from other medical conditions, according to doctors.
"She was a patient with multiple long-term conditions, including cancer," Grzegorz Materna, director of the Rzeszów Municipal Hospital, told reporters.
He added that the woman had been undergoing treatment at the hospital's anesthesiology and intensive care ward.
"Tests confirmed the presence of the bacteria," Materna said.
A day earlier, a 70-year-old man died in the same Rzeszów hospital, Polish state news agency PAP reported.
The three previous deaths had occurred at two other hospitals in the city, according to officials.
There are now five deaths and more than 70 confirmed cases of Legionella pneumophila, or Legionnaires' disease, in the Polish city close to the Ukrainian border, the PAP news agency reported.
The city’s sanitary authorities have launched an investigation into the causes of the infections and were taking measures to prevent the outbreak of an epidemic, according to reports.
Officials say they have taken water samples from public drinking-water sources and from the homes of people infected with the bacteria, among other steps.
The first results are expected on Monday, reporters were told.
As a precaution, over the coming weekend of August 26-27, Rzeszów’s water management system will undergo pest control, officials also announced.
Legionella pneumophila
According to the World Health Organisation, “the most common form of transmission of Legionella pneumophila is inhalation of contaminated aerosols produced in conjunction with water sprays, jets or mists of contaminated water sources.”
Moreover, "infection can also occur by aspiration of contaminated water or ice, particularly in susceptible hospital patients,” the WHO said.
The bacteria is not transmitted from person to person, virologist Włodzimierz Gut has told the PAP news agency.
(gs)
Source: PAP
Click on the audio player above for a report by Radio Poland's Michał Owczarek.