Code Classroom
Ron George, CPD President, Plumb-Tech Design & Consulting Services, LLC
Legionellae vs. scalding in hot water systems: a balancing act
I
recently attended an American Society of Sanitary Engineering (ASSE) dinner meeting for the Michigan chapter at which the guest speaker gave a
talk on the topic of Safe Water. The speaker had, unfor- tunately, lost two family members who died as a result of being exposed to Legionellae bacteria. They were in two different hospitals at different times for what were supposed to be routine hospital visits. The deaths were separated by time and location but tied together by the fact that, in both cases, they died of exposure to hospi- tal acquired Legionnaires disease. I am very familiar with the subject because I have
served on the ASSE Legionnaires Disease research committee, and I am a certified Legionnaires Disease prevention specialist. I have attended numerous Legionnaires Disease seminars, and I have read books, guidelines and standard publications that address Legionellae bacteria in domestic hot water systems. I have also served as an expert witness on Legionnaires Disease cases. The speaker talked about what happens when the
water that we depend on becomes contaminated with the dangerous Legionellae bacteria, which got its name from an outbreak at an American Legion convention at the Belleview Stratford hotel in Philadelphia in 1976. Hundreds of people were sickened with flu-like symp- toms, and 34 people died as a result of the outbreak. At the time the cause was thought to be a strain of the flu virus. When the bacterium was isolated, it was named Legionellae Pneumophilia. Legionellae refers to the American Legion, a kind of army, pneumo” means “lungs” and phila means “loving” in Latin. So, the bac- terium that causes the illness is “an army of lung loving bacteria,” also known as Legionnaires Disease, a severe form of pneumonia. Almost 8,000 people die every year from exposure to
Legionellae bacteria in our water, and very little is being been done proactively to prevent it. That is almost three times the number of deaths from the September 11, 2001, terrorist attacks at the World Trade Center in New York. The speaker pointed out that this would be like an event as tragic as September 11, 2001, happening once every four months in our country Legionnaires Disease typically makes national news
when there is an outbreak that involves many people. People who are exposed experience varying degrees of the illness, based on the strength of their immune sys- tems. Those with weakened or suppressed immune sys- tems fall gravely ill, and many of them die. Legionellae is ever-present in water, and it is found
naturally in the environment at low levels. When water is introduced into our manmade plumbing systems, with
Page 18/Plumbing Engineer
their warm ambient conditions, those low levels of Legionellae grow rapidly to dangerous levels. Study after study since the 1980s has proven that the plumbing systems of 70% of our hospitals are contaminated with high levels of the bacteria. Since the bacteria is resistant to chlorine and since chlorine rapidly dissipates in hot water, which is where we need Legionellae protection the most, treated chlorinated water is usually not suffi- cient to kill the bacteria. Legionellae outbreaks occur in hospitals because they
have a large population of people with suppressed immune systems. Healthy people will typically not develop an infection, even when exposed to high bacte- ria levels; a healthy immune system usually fights off infection. A patient with a suppressed immune system who comes into contact with water droplets that have a high concentration of Legionellae bacteria can become infected. Water in the form of aerosolized droplets can also come from a cooling tower or from water mist sprayers used for cooling people in hot climates. The person typically cannot see the water vapor droplets and unknowingly breathes the contaminated droplets into their lungs. Once the contaminated water droplets get to the warm moist lining of the lungs, the bacteria grows and multiplies, causing Legionnaires Disease, which is often misdiagnosed by doctors as pneumonia. Without specific laboratory tests, the disease is indistinguishable from any other bacterial pneumonia. The Centers for Disease Control and Prevention
(CDC) now realizes that the 18,000 confirmed cases of Legionnaires Disease reported each year represent approximately three percent (3%) of the real number of cases. The number of cases misdiagnosed as pneumonia is closer to 600,000 per year. The other 97% are typi- cally misdiagnosed as regular pneumonia and, without the proper antibiotic treatment, can be fatal. With the proper treatment given at the onset to high risk people, Legionnaires Disease is no more fatal than the common flu.
One would think that 35 years after Legionellae was
discovered, 25 to 30 years after research found a way to control and prevent its growth, 20 to 25 years after sev- eral types of water treatment technology was developed specifically for Legionellae prevention and after the last 12 years of several industry-sponsored guidelines being published, we would see a sharp decline in Legionnaires Disease in recent years. Sadly, that isn’t the case. In fact, despite all we know about how to prevent Legionnaires Disease, we continue to see an increase in confirmed cases. The increase may be the result of heightened awareness and more pro-active Legionnaires
Continued on page 20 March 2011
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68