Legionella Hot Spots

Disclaimer
Please note this article is for general interest and research purposes only and does not purport to give professional advice. This article should not be considered as training material or used for any other purpose.

It is widely believed that the numbers of reported Legionnaires’ disease (LD) cases are grossly underestimated; the majority of LD cases are sporadic and associated with domestic water systems. However, we can review the information supplied about outbreaks and by combining this with our understanding of building services and epidemiology we can start to reason why particular sectors are more closely associated with LD than others.

Travel

A significant proportion of reported cases are associated with travel. Possible reasons why:

• Numbers of people traveling in groups who become infected makes LD diagnosis more likely and the sources are easier to trace.
• Hotels are often implicated and the source of infection is often found to be underused showers or spas in communal areas (sports / leisure clubs). It should be noted that individual guests infected by domestic water systems in private rooms are often less likely to be detected.
• Proving the source of infection can be difficult, e.g. a conventional shower that has delivered a potentially lethal dose of legionella one day, may prove to be perfectly safe to use the next day.
• Dead legs and showers demonstrate how easy it is to produce conditions suitable for legionella multiplication and dissemination; reasons discussed in our showering articles.

Communal areas in hotels often provide the implicated source. However, is it possible that significantly more cases of LD should be attributed to underused outlets in guest rooms, which go unnoticed? Hotel guest rooms are often unoccupied for days at a time, and how many hotels have a regular flushing policy that is supported by written evidence? Travel associations and agents who recommend hotels should beware of the associated risks and of the increasing number of lawsuits against them.

Hospitals

Hospitals also regularly feature under the LD spotlight and again the majority of cases are associated with domestic water systems. Possible reasons why:

Domestic water systems are often large and complicated:

• Distribution pipe work in many hospitals is old and made from galvanized steel, which has become heavily corroded, providing environments suitable for established biofilms to develop.
• Biofilms have been shown to harbour legionella from the effects of raised temperatures and biocides.
• A maze of aging pipe work and fittings, combined with a lack of records, often proves to be a difficult legionella control challenge.

In old and large systems, small numbers of legionella are more likely to find easier passage to dead legs, and underused outlets can provide conditions suitable for rapid multiplication. Outlet considerations:

• Taps play an important part in hospital hygiene, and are normally in regular use; those which are not should be removed (L8: 164)
• Showers are often underused and it has been shown that those unused for just short periods of days are a potential risk to health and are often associated with infections; precautions should be taken, which are described in the following paragraphs of L8:
• 165: Regular flushing and monitoring
• 166: Self-purging showers are recommended when regular flushing is difficult to implement.

Many hospitals say they implement a twice weekly (or more frequent) flushing policy or have self- purging devices fitted. Enforcement inspectors should be able to inspect flushing records, which should be maintained for periods of no less than five year periods, or be able to view automatic self-purging outlets fitted.

Some of the reasons why manual flushing of showers may subsequently lapse:

• Complacency, flushing outlets can be a huge managed task in larger buildings and may subsequently lapse due to the pressures of implementing other tasks that may appear to more important at the time.
• It can be expensive to maintain, and competitive house keeping contracts may not always provide the best environment for this practice to be carried out.
• The public have poor awareness of the risks from showering and house keepers who are not adequately trained may see little reason for flushing.
• Poorly trained maintenance staff sometimes believe that cleaning showerheads on a quarterly basis is an alternative to flushing, which it is not.
• Those designated to flush showers may decide not to put themselves at personal risk and avoid flushing well-known underused showers.
• Staff changes combined with poor record keeping may cause confusion leading to a number of outlets being overlooked
• Areas may become inaccessible due to a number of different reasons,

Patients are often highly susceptible to legionella infections, especially the elderly. Patients admitted to hospital suffering from a different pre-existing disease who become infected with LD whilst at hospital are more likely to be diagnosed correctly; unfortunately the fatality rate for the elderly in these instances is believed to be significantly higher than average.

In recent times, hospitals very rarely report more than one or two cases during LD incidents, this could indicate that central systems controls are being adequately maintained, and peripheral system controls are not.

Overview

Hospitals fall under the LD spotlight for a different combination of reasons than hotels, however there are often associated factors:

• The increased likelihood of detecting LD victims, followed by correct diagnosis;
• Underused outlets which have not been flushed;
• Inadequate flushing records / no records;
• Complacency.

Hotels and hospitals are often referred to as legionella hot spots, however, in reality it would be difficult to say if these working sectors were generally better or worse than other sectors at legionella control. It would be prudent to remain vigilant to the potential risks of LD infections in all premises, and in all working sectors.

Article by:
Legionella Control Journal - www.lcj-online.co.uk