Leszek Szymański/PAP

The number of deaths from an outbreak of Legionnaires’ disease has risen to 22, health authorities in the south-eastern city of Rzeszow have said.

The latest victim of the deadly bacterium was a 74-year-old female patient at the city’s University Clinical Hospital.

A spokesperson for the hospital said the woman had been in intensive care for several days and had comorbid conditions.

In all, at least 160 people infected with Legionella have been hospitalised since the outbreak in various hospitals across the country, but most of the patients are in Rzeszow.

The health authorities are still trying to determine the source of the contamination.

Legionnaires’ disease, caused by the Legionella bacterium, is not contagious and cannot be spread directly from person to person, but can multiply in water and air-conditioning systems. Older adults, smokers and people with weakened immune systems are particularly susceptible to the disease.