Did you know there are over 50 different species of the legionella bacteria?

The most dangerous to human health is Legionella pneumophila, which is responsible for causing most cases Legionnaires’ disease. Symptoms of this infection include pneumonia, nausea, vomiting and diarrhoea, and about 10% of infected people die.

However, there are at least 19 other species of legionella that are harmful to humans. These include Legionella longbeachae and Legionella feeleii which both cause Pontiac fever, an infection that resembles acute influenza. Legionella bozemanae, Legionella micdadei, Legionella dumoffi, Legionella wadsworthii are all associated with causing pneumonia in humans.

While there are other species of legionella that can harm people, many are very rare and some have been responsible for only a single case of illness.

What all legionella species do have in common, however, is their ability to survive and proliferate in water systems such as cooling towers, swimming pools, whirlpool spas, fountains, dental equipment, industrial coolant and even car windshield washer fluid. The bacteria can lie dormant at temperatures below 20° C and will multiply rapidly at temperatures between 32° C and 42° C. Only water over 70° C is guaranteed to kill legionella bacteria instantly, although chemical treatments such as chlorine, copper-silver ionisation and chlorine dioxide can all be effective.

If you have water systems, then you effectively have to control all legionella bacteria – whether they are harmful to humans or not. There is no way of controlling just the harmful species. Legionella prevention is not only essential because it can cause fatalities, but because the bacteria can spread over significant distances. In 2003-4, an epidemic of Legionnaires’ disease at Pas-de-Calais in France was caused by an infected cooling tower at a petrochemical plant, causing illness in people who lived as far as 12 km away.

Failing to control legionella can be disastrous for your business, and not just in terms of its reputation. If you are found by a court to have not prevented the spread of the bacteria, you can face an unlimited fine and up to two years in prison. If someone dies of Legionnaires’ disease you could also face a charge of corporate manslaughter.

It’s not worth the risk. So, if you are worried that your water systems aren’t as safe as they should be, now’s the time to book a risk assessment. Once a harmful type of legionella gets into your systems, it could be too late – there is still no vaccine for Legionnaires’ disease.