Operators have responsibilities in outbreak of legionella

Failure to have cooling systems and evaporative coolers maintained and inspected puts operators and others at risk, reminds expert organization DEKRA, against the backdrop of the current outbreak of legionellosis cases in Bremen. Responsibility lies with the system operators. It is essential to break the possible chain of causes of the infection.

Just as in 2010 in Ulm and 2013 in Warstein, a spate of serious cases of legionellosis is currently being reported in Bremen. 17 cases have so far been recorded and one patient has died. Again, a cooling system or evaporative cooler is suspected to be the source of the infection in Bremen. In these systems, some of the water sprayed for cooling purposes is released into the environment in "aerosol" form (water droplets). If this water contains legionella bacteria, it can cause illness over a wide area.

Only a chain of events, that must occur successively and in sequence, will result in an outbreak of Legionnaire's disease:
1. The contamination of the cooling water with virulent legionella bacteria
2. Uncontrolled conditions enable the growth of the microorganisms
3. Contaminated droplets are released into the atmosphere
4. A minimum amount of these droplets are inhaled by vulnerable people

As an immediate measure, the professional disinfection of all relevant systems within an affected region is recommended. In order to permanently break the chain of events however, a thorough risk analysis must be carried out by an authorized expert, in accordance with VDI Guideline 2047 (sheet 2). The expert will identify defects and flaws in the system and help operators of cooling systems and evaporative coolers to avoid the contamination of the cooling or washing water by microorganisms, in particular by legionella bacteria.

In the foreseeable future, a statutory regulation for evaporative coolers will be included in the Federal Immission Control Act (BImSchG). The draft bill has been available since January 2016. Among other things, the draft bill provides for a central registration of the systems as well as regular monitoring by authorized experts.