What is Legionnaires’ disease?

Legionnaires’ disease epidemics have caused significant media attention and public health concerns. Legionnaires’ disease is a bacterial infection in the lungs, which is fatal if not treated quickly. Delta Products Group wants you to know the dangers of Legionella and how you can take preventive steps so your company doesn’t run into a Legionnaires’ outbreak. If you have boilers, chillers, or any water-operated equipment, you are at risk.

Things to note about Legionella.

  • Pneumonia-The bacterium Legionella causes inflammation in the lungs resulting in a severe form of pneumonia.
  • Bacteria-Legionella bacteria requires temperatures 68°F – 113°F and nutrients commonly found in water, scale, algae, and rust.
  • Airborne-The disease is contracted by inhaling contaminated airborne water droplets.

Why be concerned about Legionella?

  • Each year between 8,000 and 18,000 people are hospitalized in the U.S. due to Legionnaires’.
  • Since Legionnaires’ disease symptoms are congruent to pneumonia, up to 39 pneumonia deaths in the U.S. each week may be unknowingly Legionella bacteria.
  • Death rates of some outbreaks reached 50%, for cases acquired at hospitals 40%, and for community-acquired infection 20%.
  • Certain people are at higher risk. HIV patients are at 40% higher risk, organ transplant recipients at 200% higher risk, and smokers, heavy drinkers, and people ages 65+ have a moderately higher risk.

Why does Legionella thrive in your heat-exchangers?

Cooling towers run at optimum temperatures for the Legionella to thrive.

Cooling towers provide a method of aerosolized water for the Legionella to attack humans.

  • Legionella bacteria resides in water. If infected water becomes aersolized from a heat-exchanger, water fountain, car wash, or any other device that may aerosilze the water it can be carried through the air it is able to be inhaled and reach the lungs to infect them.

Cooling towers are often debugged without descaling or anything taking care of biofilm.

  • Scale is porous and provides an area for the Legionella to accumulate and can trap water so that biocides can’t access it. This can allow Legionella to avoid any cleaning attempts and infect water introduced into the system.
  • Scale also provides calcium which benefits the Legionella in several ways.
  1. The excess calcium aids the Legionella in binding to nonliving surfaces allowing it to accumulate and form more biofilms.
  2. It creates areas that biocides have difficulty reaching.
  3. Calcium also aids in the metabolic process of Legionella.
  • Biofilms occur when there is enough Legionella to make it.
  1. Legionella forms a biofilm to react to non-ideal or dangerous conditions for protection.
  2. Attempts to rid a system of Legionella are thwarted by biofilms as biocides cannot penetrate the biofilm.
  3. Within the biofilm, the Legionella will multiply safely and when there is enough the biofilm will release a new wave of Legionella that can reinfect water systems.
  4. If dead bugs are left in the system the Legionella is able to feed off of them. Meaning that unless you get all of the Legionella they are able to repopulate in a short amount of time.
  5. Biofilms can also house multiple types of Legionella and this can result in increased virulence.
  6. Also, Legionella that comes from the biofilm has been shown to evade the natural processes in humans to resist Legionnaire’s, making it easier to become infected.
  7. Biofilms have also been shown to find locations that are less affected by turbulent flow and therefore are able to minimize contact with circulated solutions.
  8. Biofilms can also put the Legionella into a state that inhibits the ability of the system to be properly assessed.

Cooling tower components are made of materials that aid Legionella.

  • Galvanized is made up of zinc-treated stainless steel and is fairly ubiquitous in the cooling tower components.
  1. Zinc helps the Legionella adhere to host cells in humans.
  2. Iron is essential for Legionella survival so any under deposit corrosion or rust will push extra iron into the system and raise the carrying capacity of the system for Legionella.
  3. Iron also aids in Legionella forming multi-species biofilms, which allows the formation of biofilms in a system with less Legionella.
  4. The multi-species biofilms allow the Legionella to form with other bacteria which allows the Legionella to take on additional characteristics that aid in its survivability most notable being heat resistance.

What you can do to prevent a Legionnaires’ outbreak.

  • Delta Products Group provides three ways of helping your heat-exchanger with safe biodegradable cleaning chemicals.
    1. Bio-Soak is specially formulated to destroy biofilms built up by Legionella.
    2. 888 DESCALE and all of our descaling products are safe cleaning chemicals that dissolve scale in your systems.
    3. Our descaling products take care of rust, lime, algae, and other water deposits. To help lasting results, we provide chemicals like RustCoat to prevent flash-rusting from reforming.