Legionella pneumonia was in the news again last week due to cases traced to Disneyland® cooling towers in Southern California. Of the 12 reported cases as of this writing, one patient has died. After the New York City outbreak in the Bronx in 2015, strict testing and reporting standards were instituted statewide. All towers are tested quarterly with water samples sent to a state certified testing facility. Any result that records greater than 20 CFU/mL but less than 1000 CFU requires online disinfection and retest in 3-7 days. When less than 20 CFU/mL is reached, routine maintenance continues. Greater than 1000 CFU requires state notification, online decontamination and retest. If any retest continues to be greater than 1000 CFU/mL, the cooling tower must be drained, decontaminated, and retested until it is below 1000 CFU/ml.
Mike Bromley, President of Water Wise of America lives and works in upstate New York and is our premier industrial ProMoss™ dealer. I called Mike and asked him to look up the records on the ProMoss™ treated towers he treats and the results of the Legionella testing.
Mike has 68 cooling towers being treated with ProMoss™ and either chlorine or hydrogen peroxide as the required biocide. To date he has had two towers with low levels of legionella. Both were new starts on ProMoss™. One had a problem with the biocide delivery and the other had the test taken from a non-flow area of the basin. Neither required state notification and both were negative after online decontamination.
So why does ProMoss™ along with a biocide provide these results? The answer is organic contamination.
ProMoss™ inhibits the formation and removes existing organic contamination from the surfaces of the water containing structure. Legionella are very unusual bacteria. They thrive inside organisms that usually kill them. In water containing structures like cooling towers, organic contamination accumulated on surfaces and amoeba feed on the organic contamination. Amoeba ingest legionella bacteria but can’t kill them, so they grow inside the amoeba until they kill the amoeba. The Legionella then swim free and can be transferred by droplets of water to another host. If that host is a human, legionella are eaten by lung macrophages and do the same thing to the human macrophage that they did to the amoeba. The end result is destruction of lung tissue and often deadly pneumonia.
We think ProMoss™ removes the food source for amoeba by inhibiting the formation and removal of organic contamination. As the amoeba die, the biocide can kill the swimming legionella.