What then is Legionnaires’ disease?
Legionnaires’ disease is classified by the Health and Safety Executive (HSE) guide for duty holders, as a “pneumonia-like illness caused by Legionella bacteria”. There are different variants of the disease including the most serious Legionnaires ’ disease, along with less serious conditions of Pontiac fever and Lochgoilhead fever.
Who is at risk?
We are all susceptible to infection from Legionairres’ disease, though some groups are at a higher risk including:
· People over 45 years of age
· Smokers and heavy drinkers
· People suffering from chronic respiratory or kidney disease
· Anyone with an impaired immune system
According to NHS figures, in 2009 there were 345 reported cases of Legionnaires’ disease in England and Wales, and it is thought 163 of those cases occurred whilst the affected person was travelling abroad. It is estimated that 1 in every 10 cases will prove to be fatal. The true figure of Legionnaires’ cases is thought by some experts to be much higher, as often patients presenting with pneumonia-like illnesses are not tested for Legionnaires’ disease.
What are the causes of Legionnaires’ disease?
The bacterium Legionella pneumophilia and related bacteria are widely found in natural water systems, such as rivers, lakes and reservoirs. As the bacteria is so widespread in the natural environment, it can spread to a purpose-built water supply, such as cooling towers, evaporative condensers, hot and cold water systems and whirlpool spas.
The risk that Legionella bacteria growth can occur in the workplaces is described on the HSE guide for dutyholders as follows:
· Water is stored or re-circulated as part of your system;
· The water temperature in all or some part of the system is between 20-45 °C;
· There are sources of nutrients such as rust, sludge, scale and organic matters;
· The conditions are likely to encourage bacteria to multiply;
· It is possible for water droplets to be produced and, if so, if they can be dispersed over a wide area, e.g. showers and aerosols from cooling towers; and
· It is likely that any of your employees, residents, visitors, etc are more susceptible to infection due to age, illness, a weakened immune system, etc. and whether they could be exposed to any contaminated water droplets.
What are the symptoms of Legoinnaires’ disease?
The symptoms, as described by the NHS, can begin any time from 2 to 19 days after exposure to the initial infection. However 6 to 7 days is the most common timeframe between contracting the infection and the onset of symptoms, known as the incubation period. Symptoms usually come in phases, with the initial phase being mild headaches and muscle pain, followed by the onset of more severe symptoms, including:
· High fever, sometimes a temperature of 38°C (100.4°F) or above
· More severe muscle pain
· Changes to your mental state, such as confusion
Once the bacteria begins to infect your lungs, you may also experience symptoms such as a persistent cough, shortness of breath and chest pains. Some people with Legionnaires’ disease can also experience nausea, vomiting, diarrhoea and loss of appetite.
At what point should you seek medical advice?
The symptoms of high fever are almost always caused by an infection. If you have a high fever, contact your GP as soon as possible to consider the various possibilities. Alternatively, you can phone NHS Direct on 0845 4647 for help and advice.
How can the spread on Legionnaires’ disease in the work place be prevented?
Large buildings, such as hotels, hospitals, museums and office blocks are more susceptible to outbreaks of Legionella contamination due to the complex water supply systems they have in place. There is therefore strict guidelines in place regarding the maintenance and control of these water systems, such as either keeping the water cooled below 20°C (68°F) or heated above 60°C (140°C) to prevent conditions in which an outbreak of Legionnaires’ disease can occur.
You should ensure that you have in place a competent person, either directly employed or from an accredited Building Management company, who has the knowledge and expertise to understand your water systems and any associated equipment. In order that they can implement regular maintenance to monitor, inspect, record and identify any risk that Legionella may be present in the water system, allowing them to implement any control procedures that are necessary.
As advised in the HSE guide for dutyholders, you should also consider whether you can prevent the risk of Legionella in the first place, by replacing a wet cooling tower, with a dry air cooled system, as with the Daikin equipment described earlier, which eliminates the risk of conditions where the Legionella bacteria can be found.
In accordance with HSE guidelines, if you identify a risk that you are unable to prevent, you must introduce appropriates controls to prevent the spread of the Legionella bacteria. If you have a case of Legionellosis in an employee who has worked on cooling towers or hot water systems that are likely to be contaminated with Legionella, you must report this under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR).
It is important to remember that this document has been put together as a guide based on our knowledge and experience of the issues described. The sources for which are readily available in the public domain from the HSE, NHS, BBC Health and leading air conditioning equipment manufacturers. We would always encourage you to seek further information from the relevant sources for the most up to date advice.