Legionnaire’s Disease is an environmentally transmitted
disease, which infects human hosts who breathe minute
droplets of water that have been contaminated with the
Legionella organism: a gram-negative bacterium. Aerosolized
water from sink traps and showerheads are the most common
sources of Legionella organisms available for human
exposure from residences. In commercial buildings, medical
buildings and healthcare institutions, the most likely
sources are hot water and cooling towers. In medical
facilities, it is not unusual to set the hot water temperature
low (100-120°F) so as not to burn people but this creates
a possible growth environment for the Legionella Bacteria.
Cooling towers receive warm or hot water and cool it,
but the warm water can be an incubator for Legionella
if not properly treated. In other cases, hot tubs—and
saunas—that were not properly treated with a bactericide
have been sources of Legionnaire’s Disease and Pontiac
Fever.
Legionella thrives in water temperatures between 95
degrees and 115 degrees, Fahrenheit. Its growth is inhibited
at temperatures outside this range.
Legionella is ubiquitous. It is likely to be found
in every water system to some degree. But, just because
Legionella is present, doesn’t mean infection will occur.
Sometimes, people who are hospitalized with respiratory
problems are tested for Legionella antibodies, and show
a positive test. This doesn’t necessarily mean the patient
has a case of Legionnaire’s Disease. Most people have
developed antibodies to Legionella without ever becoming
infected.
Legionnaire’s Disease first came to our attention in
July, 1976, when 240 attendees at an American Legion
Convention in Philadelphia were struck by an unrecognized
respiratory disease that claimed 34 lives (wikipedia.org/wiki/legionellosis).
After many months’ investigation, the causative agent,
a previously unknown bacterium, Legionella pneumophila,
was identified. Today, there are 48 known species of
Legionella. A milder form of this infection is called
Pontiac Fever (wrongdiagnosis.com/p/pontiac_fever/intro.htm),
named for a 1968 outbreak in Pontiac, Michigan. Both
Legionnaire’s and Pontiac Fever are caused by the same
Legionella pneumophila bacterium. Patients with Pontiac
Fever do not have pneumonia, unlike those with Legionnaire’s
Disease.
The best way to minimize the possibility of a Legionella
outbreak is through proper maintenance of the water
system especially the hot water systems. This includes
identifying and removing “dead legs” in the piping which
contain stagnant water; removal of scale, sediment and
biofilm, controlling temperatures in the system and
regular treatments with biocides. Consulting a local
water treatment lab can provide you with a list of biocides
that will be effective in controlling Legionella and
at the same time minimize corrosion to the system’s
tanks and piping. Sending them a water sample, can determine
if the bacteria is present.
The only way to know for sure if your facility’s water
system is harboring potentially harmful levels of Legionella
is to test the water. The USEPA approved procedure is
to take two samples from a faucet; one is a “first catch,”
collected when the hot water faucet is turned on. The
second sample is collected after the hot water has been
allowed to run long enough for the water leaving the
faucet is as hot as it will get. These samples and the
Legionella organism are fragile and must be in the hands
of the lab very quickly, but not more than 24 hours
after collection. Ridding a system of Legionella Bacteria
is a difficult task since they are ubiquitous (osha.gov/dts/osta/otm/legionnaires/index.html).
If you rid the system of Legionella Bacteria but don’t
eliminate the environment for their growth, they will
return.
Once someone has been diagnosed with Legionnaire’s
Disease, especially in multi-family housing, commercial
building, or healthcare facility, the local health department
must be contacted. Thereafter, the efforts to identify
the source and eliminate the source—and causes—will
require the assistance of qualified professionals.
For more information on Legionnaire’s Disease, go
to:
atlenvtexas.com/legionnaires-articles.htm
mayoclinic.com/health/legionnaires
disease/D500853
or contact us @ 800-344-4414
info@atlenv.com
