Climate change leads to spread of Pneumonia-causing bacteria, expert says

A warmer climate and Europe’s ageing population create a favourable breeding ground for legionella bacteria, which cause a type of pneumonia known as Legionnaires’ disease, Professor Martin Exner said in an interview.

“What we are seeing now is that temperatures are increasing even in cold water, so Legionella bacteria also increase,” said Exner, who is Director of the Institute for Hygiene and Public Health at University Clinic Bonn.

Temperature rise due to climate change makes water systems and cooling towers warmer, Exner explains. This creates an ideal environment for spreading bacterial cultures of Legionella, and especially Legionella Pneumophila which causes a deadly form of pneumonia.

The legionella bacteria spreads through mist, which can come from air-conditioning units of large buildings. Adults over the age of 50 and people with weak immune systems, chronic lung disease or heavy tobacco users are the ones most at risk.

In Germany, between 16,000 to 30,000 Legionnaires disease cases are reported every year. “Up to 90% of those patients need hospitalisation. And it costs public money,” Exner pointed out.

The increase in the numbers of observed cases, in particular since 2017, is also driven by other factors, according to the European Centre for Disease Prevention and Control (ECDC). This includes improved surveillance, an ageing population, as well as travel patterns.

“For instance, when you go to a hotel at the beginning of the holiday season, you could be in a room where water is standing for a long time in shower tubes,” explained Exner. “So you take a shower and can be infected.”

Solutions to manage the presence of bacteria until proper disinfection that lowers the concentrations may involve filtration systems to put at the shower outlet, the expert suggested.

ECDC: Legionella outbreak may be reduced with appropriate controls

A new community outbreak of Legionella in Belgium’s Flanders region renewed public attention to the so-called Legionnaires’ disease, which is increasing in the EU, according to the EU agency for infectious diseases control.

Drinking water and Legionella

The change in the vulnerability of the population has increased the risks of so-called opportunistic pathogens that come exclusively from the environment around us, like legionellosis.

“One can say drinking water is already controlled, as we are doing tests for E.coli, for instance, or for pathogens of cholera or typhoid fever,” said Exner.

However, although traditional tests can spot these pathogens in water they are no good for detecting Legionella bacteria, Exner explained, saying further indicators are needed there.

“In Germany, but also in France and in the Netherlands, we have now a legal obligation to look also for numbers of Legionella bacteria, at least in the warm parts of the drinking water installation, twice a year,” Exner said.

The issue of monitoring Legionnaires’ disease is touched upon in Annex III of the new Drinking Water Directive (DWD), which updates water quality standards set more than 20 years ago.

The updated directive has entered the so-called “trilogue” stage, where representatives from the 28 EU member states and the European Parliament sit together to strike a compromise, with assistance from the European Commission.

Inter-institutional meetings started this week with a first exchange of views. The next meeting will take place on 22 October in Strasbourg, an EU source told EURACTIV.

A new rapporteur for the European Parliament, Christophe Hansen MEP from Luxembourg, was appointed to replace outgoing MEP Michel Dantin, who took care of the file in the past legislative term.

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Risk approach

According to Exner, laboratories should not see only the concentration of the bacteria, but rather adopt a risk approach trying to detect first Legionella pneumophila serogroup 1, the bacteria that causes most of Legionnaires’ diseases infections.

Mandatory testing in France already requires detection for Legionella pneumophila since 2001 and reported cases in France rose at half the average rate of increases across 30 European countries in 2013-2017 time.

In Germany, clinical tests usually focus on detecting the virulence of Legionella pneumophila serogroup 1 and when higher concentrations are detected, actions are put in place the lower the presence of the bacteria.

To explain this risk-based approach, Exner gave the example of a cooling tower in the middle of Bonn that is checked regularly every month.

In August, a colony of 200,000 bacteria of Legionella serogroup 1 was found, a quantity unable to cause an outbreak but potentially dangerous. “We asked to disinfect immediately the tower because the situation could lead to a very high-risk situation.”

Testing all Legionella species or just the one with the highest risks of infection, namely the Legionella pneumophila serogroup 1, is still a matter of technical discussions between the European Parliament and EU national representatives in the framework of the Drinking Water Directive (DWD).

“I’m very convinced we should look for Legionella pneumophila first as it happens already in the medical area,” said Exner.

If you’re diagnosed with pneumonia, he continued, the physician gets to test you for being infected only with Legionella pneumophila serogroup 1, not with other legionnaires.

“We have this big discrepancy between medical diagnosis for Legionnaires diseases and laboratory for analysing drinking water systems,” he said, adding that he is not a hunter of all Legionella species, but he only wants a drinking water system with no risk for legionellosis contagion.

[Edited by Frédéric Simon]


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