Report: Legionella found in over half of tourist facilities evaluated in Balearic Islands

Surveillance of Legionella in tourist facilities of a major European holiday destination found the pneumonia-causing bacteria present in over half of the evaluated areas.

A study published by the medical journal Eurosurveillance found that the bacteria had contaminated over 65% of all tourist facilities evaluated in the Balearic Islands, Spain.

A total of 465 tourist facilities, including hotels, apartments and agritourism resorts located in the Balearic Islands were surveyed over two different periods: from 10 January 2006 to 21 October 2010 and from 12 January 2015 to 27 December 2018.

The contamination found in the Spanish islands is similar to what has been reported in studies conducted in Hungary, Greece and the Netherlands, but remarkably higher than rates reported in studies performed in, for example, Croatia.

While the prevalence of Legionella in hotels in similar destinations such as Greece, Italy, or Turkey has been widely investigated, information from Spanish tourist facilities remains scarce, the authors of the study pointed out.

Legionnaires’ disease occurs by inhaling aerosols carrying the Legionella bacteria, which develops primarily in warm, stagnant water.

The subsequent infection ranges in severity from a mild influenza-like illness to a serious and sometimes fatal form of pneumonia. Symptoms include fever, headache, lethargy, muscle pain, diarrhoea and sometimes coughing up blood.

There are more than 60 known Legionella species; however, according to leading health bodies, roughly 96% of Legionnaires’ disease is caused by just one specific species, Legionella Pneumophila, which is also responsible for the deadly form of pneumonia.

Hot and cold (water)

Legionella bacteria spread through vapour which can commonly 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 those most at risk.

Hot and cold water systems are the second most common source of infection.

The installation of the tanks of hot water distribution systems (WDS) can bring considerable risks, as they have higher bacterial loads and an increased rate of highly contaminated samples. The authors of the study advised “specific interventions to improve these particular installations.”

“They may include increasing the temperature and the frequency of cleaning and disinfection which currently is yearly,” the study reads.

However, Legionella was detected only in over 15% of the hot water distribution systems samples, a level of contamination lower than reported in other European countries, including Greece, Italy and Hungary.

Regarding cold WDS samples, Legionella was found in 7% – a lower figure when compared with other European studies conducted in hotels and healthcare facilities.

Cold WDS are considered low-risk installations, “however, fatal cases of legionellosis have been linked to cold WDS, and evaluation of these installations should be routinely performed,” study said.

EU legislation recently improved

In 2019 in the European Union and European Economic Area, 28 countries reported over 11,000 Legionnaires’ disease cases – the highest rate of notification ever recorded.

Spain was one of the countries with the most reported cases, among both locals and tourists being diagnosed shortly after returning from Spain.

Researchers are urging hotels to implement water safety plans with continuous water quality monitoring and periodic sampling.

The EU has recently improved the current legislation to tackle the spread of the pneumonia-causing bacteria by revising the Drinking Water Directive (DWD) and extending Legionella monitoring to every potable water system in the EU as part of the new risk assessment analysis.

After the final approval in December 2020, the new rules entered into force on 12 January 2021, with member states having two years to transpose them into national legislation.

Other approaches

“Current practices seem to reduce bacterial proliferation in the installations but are not effective in avoiding pathogen entry,” the study warned.

The control of Legionella is mainly happening through chlorine derivatives and water temperature. Water disinfection, mainly with chlorine derivatives, is a crucial strategy for Legionella control in cold WDS.

In Spain, the legislation for the prevention of Legionnaires’ disease in cold water establishes that chlorine levels should not drop below 0.2 mg/L in the WDS. In addition, drinking water legislation restricts the levels of this disinfectant to a maximum of 1 mg/L.

[Edited by Nathalie Weatherald]