Two people may have died and 11 others been infected with Legionnaires’ disease spread via a central heating boiler, public health institute RIVM said on Thursday.

Manufacturer Ferroli has now issued a warning on its Dutch website about two types of boilers – BlueSense and BlueHelix – saying versions made after January 2022 may be a problem. It is calling on owners to have their boilers cleaning to reduce the risk of the bacteria spreading.

The Dutch food and product safety board NVWA, which also published a warning, said some 1,400 boilers of the two types had been sold in the Netherlands in 2022.

Several health boards reported cases of Legionnaires disease from July that year which were likely to have originated in the boilers, the RIVM said.

Legionella bacteria are found naturally in freshwater environments, such as lakes and streams and become a problem when they grow and spread in human-made building water systems, such as boilers.

Symptoms of Legionnaires disease include respiratory infections and severe pneumonia. The chance of dying from the disease is relatively small but the elderly and people with underlying health problems are particularly prone to developing pneumonia, which can be lethal.

Ferroli was not able to provide the RIVM with the addresses of people who had bought the boilers at short notice, which is why it was decided to publish the safety warning, NOS said.

It is the second time Ferroli boilers have hit the headlines. In 2019 some 150,000  were branded fire hazards by consumer tv programme Kassa, which claimed several homes had been set on fire after technical problems has caused the boilers to melt.

One of the biggest outbreak of Legionnaires disease in the Netherlands took place at a flower show in Bovenkarspel in 1999. Two whirlpool spas and a sprinkler were found to be contaminated, resulting in 32 deaths and over 200 infections.