Legionella pneumophilia

More information on Legionella and prevention of water borne pathogens

Drinking water in many developed countries has stringently controlled standards. Therefore it is difficult to imagine that water for human use, delivered through taps and shower heads, could contain harmful pathogens.

However, bacteria such as the Legionella pneumophilia and Mycobacterium avium (both 0.5 – 0.7 µm in size) occur naturally in surface water and are frequently found in shower plumbing. The bacteria can reproduce to high levels in the slimy layer (biofilm), which forms on the inside of water pipes that are filled with stagnant or slow moving warm water.

Such situations can be found in the plumbing of large buildings such as hospital, nursing homes, apartment buildings, hotels, sports centers, camping grounds and vacation homes in warm climates that are unoccupied for part of the year.

Legionella bacteria are released from the biofilm into the water stream and reach users when taps or showers are opened. To cause an infection, the contaminated water must be vaporized and inhaled, after which the bacteria can settle in the lungs, causing the so-called Legionnaires’ disease, largely the same as the pneumonia symptoms related to the M. avium bacteria. This can easily happen if someone takes a shower or inhales contaminated water vapor over a kitchen sink.

The first reported outbreak occurred in 1976. Army veterans assembled in a hotel in Philadelphia, which had been unused for a period, were infected with pneumonia en masse. Investigation showed that the outbreak was due to the presence of certain bacteria in the water, which were called Legionella pneumophilia, because the first known outbreak affected army veterans (legionnaires).

The higher the bacteria concentration in the inhaled water vapor, the more likely an infection will occur. It has been demonstrated that the risk of infection is much greater at lower levels for the elderly, smokers and people with compromised immune systems. The fever variant (or Pontiac fever) is the mildest form. Legionnaires’ disease on the other hand can deteriorate into a chronic condition of the lungs with a fatality rate of approximately 15%.

Legislation requires that there shall be no stagnant water in shower plumbing and that disinfection with chemicals and/or hot water at 80 °C as well as regular flushing of the plumbing must be done.

Quite often, structural adaptations appear to be impractical or impossible. In spite of all the measures that are taken, it is extremely difficult to eradicate biofilm once established. As a result, the presence of the Legionella bacteria persists. Recent scientific studies have shown that Legionella bacteria feed on dead organic material, which stimulates the multiplication of remaining colonies after disinfection cycles.

Filtration at the point of use is therefore an obvious solution to prevent outbreaks. 

Prime Water’s focus is safe water at the point of use when needed. The PW shower heads are fitted with a 0.15 µm membrane filter that stops all bacteria, including Legionella pneumophilia, when needed. It provides protection even if the problem persists for several months.

H36 shower with disposable membrane filter

A comforting thought to all facility managers, who dare not think of the consequences of closing down the showers in their facility. Prime Water provides the means to handle the problem professionally and keep the showers open.

Countless hospitals, hotels and other public buildings have already been equipped with Prime Water^® Legionella Safe showers.