Hunt is on for source of deadly Legionnaire outbreak

As infectious disease experts, public health bodies and the Health and Safety Executive grapple with the problem, it’s been predicted that the number of victims will keep rising until the weekend due to its incubation period of up to 14 days. Potential sources under investigation are industrial water cooling towers.

Legionnaires’ disease is the pneumonia-like illness caused by legionella bacteria. In England, about 200 cases a year are reported and most are single incidents.

In recent years about a third of cases in England and Wales have been as a result of infection while travelling in another country. The disease is spread through the air from a water source, and breathing in mist from a contaminated water system.

Legionella bacteria are normally present in natural water systems such as rivers and ponds – however the conditions are rarely right for humans to catch the disease from these sources.

Outbreaks occur from exposure to Legionella growing in purpose-built systems where water is maintained at a temperature warm enough to encourage multiplication of the organism – for example in water cooling towers, evaporative condensers, spa pools and hot water systems used in all sorts of work and domestic premises.

The Health and Safety Executive says certain conditions increase the risk from Legionella, including: water temperature between 20-45C, which is suitable for growth; creating and spreading breathable droplets of water, the aerosol of water droplets suspended in the air by a cooling tower or water outlets; stored or re-circulated water and a source of nutrients for the bacteria such as sludge, scale or fouling.

If you are an employer or someone in control of premises (eg a landlord) it is your duty to manage Legionella risks, carrying out a legally required and regularly reviewed risk assessment.

“We are hearing less about Legionnaires’ disease, probably because modern buildings have better water systems,” says health and safety consultant Sarah Daniels. “Water has to be kept cool or hot, and water temperature has to be taken regularly. Legionella multiply in warm water that is left sitting in a tank rather than being run off regularly. As for who is likely to suffer from Legionnaires’ disease, middle-aged men who smoke and drink are most at risk, as both of these lower the immune system. Keeping fit and healthy strengthens your resistance.”

A spokeswoman for the Health Protection Agency said: “It’s important to be aware that even where Legionella bacteria are present in water, the disease is not caught easily. For a person to become infected, the bacteria need to have been dispersed into the air in aerosol form from a contaminated water source. Person-to-person spread does not occur, so there is no risk to others from a person with Legionnaires’ disease.

“All ages can be affected, but it mainly affects people over the age of 50 years. Men are three times more likely to get Legionnaires’ disease than women. Individuals with underlying medical conditions such as heart, lung or liver disease – those with impaired immune systems – are also at greater risk from the disease. Smoking is also considered a significant risk factor.”

The HPA say there is currently no increased risk to people in Yorkshire as a result of the Legionnaires’ disease outbreak in Scotland. If anyone is concerned that they may have symptoms of the condition, they should contact their GP in the usual way.

If you are travelling abroad, be aware of the risk of Legionnaires’ disease and if you are at increased risk – for example because you have a weakened immune system – you may want to consider avoiding water systems that could be contaminated, which include spas and hot tubs.

Early symptoms of Legionnaires’ disease are mild headache and muscle pain, followed by high fever, possibly a temperature of 38C (100.4F) or above, more severe muscle pain, chills, tiredness and altered mental state such as confusion.

Once the bacteria begin to infect the lungs, there may be a persistent cough, shortness of breath and chest pains.

Some people with Legionnaires’ disease also have digestive symptoms like nausea, vomiting, diarrhoea and loss of appetite.

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