More Cases

Legionella Outbreak: Evidence Is Mounting

Rapid tests for Legionella are being evaluated at the University Hospital in Linz.(Bild: FOTOKERSCHI / BILAL AHMETOVIC)

There are two more people who have fallen ill in the Legionella outbreak in Linz. More and more evidence points to a large air-conditioning system that cools an electrical substation and disperses water droplets into the air. However, nothing is certain yet; a genetic analysis is expected to provide clarity.

Two more patients, but no additional deaths—the total number of people affected by the Legionella outbreak in Linz now stands at 28. Three of them have died—two people over 80 with serious pre-existing conditions, as well as a 56-year-old man from Linz who was physically fit. “Four patients are still in the hospital, but none are in the intensive care unit,” was the status as of Friday afternoon.

“No Connection to the Piping System”
The search for the source of the outbreak that infected the 27- to 94-year-old victims with Legionella is not yet over, but a large air-conditioning unit belonging to Linz AG—which cools the power grid building on Wienerstraße—is increasingly coming under scrutiny. “The rooftop unit in question is part of a self-contained cooling system that runs from the roof of the building to the heat pump and back to the rooftop unit. The system is separate from the building’s piping system,” according to Linz AG, which also explains how it works: To cool the rooftop unit—specifically the pipes inside it—water from an external tank is sprayed onto the pipes. Legionella bacteria were detected in this water tank within the rooftop unit. It has since been cleaned and disinfected multiple times, and there is no connection to the building’s piping system.

Construction Site Dust Under Suspicion
“Evidence has since mounted that contamination from concrete or cement dust originating from major construction sites in the immediate vicinity of the system significantly contributed to the growth of Legionella bacteria within the system. The dust entered the system, settled there, and negatively impacted the effectiveness of the automatic, periodic chemical disinfection,” according to Linz AG, which is working to fully clarify the situation.

Antibodies Match
Most of those who fell ill live near the facility or have at least been there. And in several infected individuals, an antibody—the so-called MAb type—matches the one found in the Legionella strain detected in the air conditioning system. Genetic testing is now underway, and results are expected on Monday.