Legionellosis is a collective term for diseases caused by legionella bacteria including the most serious Legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. The risk increases with age but some people are at higher risk including:
The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They may also be found in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools.
If conditions are favourable, the bacteria may grow increasing the risks of Legionnaires’ disease and it is therefore important to control the risks by introducing appropriate measures outlined in Legionnaires’ disease – The Control of Legionella bacteria in water systems.
Legionella bacteria are widespread in natural water systems, e.g. rivers and ponds. However, the conditions are rarely right for people to catch the disease from these sources. Outbreaks of the illness occur from exposure to legionella growing in purpose-built systems where water is maintained at a temperature high enough to encourage growth, e.g. cooling towers, evaporative condensers, hot and cold water systems and spa pools used in all sorts of premises (work and domestic).
People contract Legionnaires’ disease by inhaling small droplets of water (aerosols), suspended in the air, containing the bacteria. Certain conditions increase the risk from legionella if:
Pseudomonas aeruginosa is the definition of a tough bacterial strain, able to survive in harsh environments. It is found widely in soil and stagnant water, and can infect humans and plants.It does not usually cause illness in healthy people, but is described as an “opportunistic” organism, causing serious infection when our normal defences are weakened. This means that it represents a genuine threat to the most vulnerable hospital patients, most commonly intensive care patients, those with depleted immune systems such as cancer patients, people with severe burns and premature babies in neonatal units.
The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They may also be found in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools.
If conditions are favourable, the bacteria may grow increasing the risks of Legionnaires’ disease and it is therefore important to control the risks by introducing appropriate measures outlined in Legionnaires’ disease – The Control of Legionella bacteria in water systems.
The severity and type of the illness it causes depends on its route into the body. If it enters lung tissue, for example in a cystic fibrosis patient, it can cause a form of pneumonia. Infection of a skin wound or burn can lead to extensive tissue damage or even septic shock. If the bacterium infects the gastro-intestinal system of a vulnerable patient, then a condition called “necrotising enterocolitis” can follow, which again causes severe tissue damage. This is the form most associated with premature babies.
Pseudomonas aeruginosa is a relatively common type of infection encountered in UK hospitals, and its tough nature and the severity of the symptoms it causes mean it is a priority for infection control departments. There have been a number of outbreaks in hospitals in the UK, with the source sometimes traced back to contaminated water in sinks and drains. It has the ability to survive for up to several days on surfaces, further increasing the risk of it being passed on to patients.
Latest figures suggest that the number of Pseudomonas infections is fairly steady, with between 3,700 and 4,000 cases reported to the Health Protection Agency each year. Nine out of 10 of these were the Pseudomonas aeruginosa strain. Rates were highest in the London region, and the majority of cases were in the elderly and babies under one year old.
The usual route is through contaminated hands or medical equipment such as catheters and feeding tubes.
Infection control measures such as regular handwashing and decontamination of equipment are the most effective tactics to prevent its spread.
Once established in a weakened patient, a Pseudomonas aeruginosa infection is potentially a severe problem which requires immediate treatment.
While mortality from the infection varies depending on where the infection is, how soon it is treated and the underlying weakness of the patient, some studies suggest a third of infected patients may die.
The bacterium appears to have an inbuilt resistance to antibiotics, as well as the ability to mutate into new, even more resistant forms.
However, there are still a number of antibiotic drugs which can tackle it, and latest statistics in the UK suggest that the number of strains with resistance to any of these individual standard drugs remains fewer than one in 10.
Sick building syndrome (SBS) is a poorly understood phenomenon where people have a range of symptoms related to a certain building, most often a workplace, and there is no specific identifiable cause.
The symptoms of SBS may include:
The symptoms of SBS can appear on their own or in combination with each other and they may vary from day to day. Different individuals in the same building may have different symptoms. They usually improve or disappear altogether after leaving the building.
Anyone can be affected by SBS, but office workers in modern buildings without opening windows and with mechanical ventilation or air conditioning are most at risk. This risk increases if they are employed in routine work that involves using display screen equipment.
Women appear to be more likely to develop the symptoms of SBS than men. However, this may be due to more women being employed in offices rather than a higher susceptibility.
SBS seems to be associated with certain types of buildings. Most cases of SBS occur in open-plan offices, although people sometimes develop the symptoms while in other buildings that are occupied by lots of people, such as:
Since the 1970s, researchers have tried to identify what causes SBS. As yet, no single cause has been identified. However, most experts believe that SBS may be the result of a combination of different factors.
Possible risk factors for SBS may include:
If you think that your working environment is making you ill, talk to your colleagues to see whether they are having similar symptoms.
If SBS appears to be a workplace issue, raise it with your health and safety representative. Your employer has a duty of care to investigate the problem.
The environmental health services of your local authority or your local Health and Safety Executive (HSE) office may also be able to provide help and advice about how to deal with SBS.
You can visit the Directgov website to find your local authority. To find your local HSE office you can call their helpline number on 0845 345 0055.
Visit your GP if you have symptoms of SBS that you are particularly concerned about.
The HSE recommends that employers take the steps outlined below to investigate the possible causes of SBS.
Once the steps listed above have been completed and any necessary actions have been taken, employers should carry out another employee survey at a later date to find out whether the symptoms of SBS persist.
If SBS symptoms are still present, a more detailed investigation will be required. This can be carried out by a building services engineer or another similarly qualified consultant.
As an employer or a person in control of premises, you must appoint person or persons responsible for helping you manage your health and safety duties, e.g. take responsibility for managing risks. A competent person is someone with the necessary skills, knowledge and experience to manage health and safety, including the control measures. You could appoint one, or a combination of:
If you decide to employ contractors to carry out your risk assessment or other work, it is still the responsibility of the competent person to ensure that the work is carried out to the required standards. Remember, before you employ a contractor, you should be satisfied that they can do the work you want to the standard that you require. There are a number of external schemes to help you with this, eg A Code of Conduct for service providers.
The purpose of carrying out a risk assessment is to identify and assess any risks in your water system. The responsible person should understand your water systems and any associated equipment, in order to conclude whether the system is likely to create a risk from exposure to legionella, and should be able to identify whether:
Your risk assessment should include:
If you decide that the risks are insignificant, your assessment is complete. You may not need take any further action at this stage but you should review the assessment regularly in case anything changes in your system.
Yes. There may be other factors within your system that increase the risks of legionellosis, eg deadlegs, showerheads and/or long runs of pipe work containing warm water. A risk assessment should also consider anyone who could be potentially exposed to any legionella bacteria in your system, and particularly groups that are at a higher risk of contracting legionellosis. However, once you have completed your risk assessment you may decide that the risks are insignificant. If you do, you need take no further action other than to review the assessment regularly in case anything changes in your system.
