The bacterial strain known as Legionella was first discovered in late July of 1976 at an American Legion conference in Philadelphia. If you have never heard of American Legion before, click here for a bit of learning. Though little did these men at the conference know that they were about to face an invisible legion, unable to be fought with guns and tanks. In the days following, 221 men became seriously ill while 34 veterans wouldn’t live to tell the tale. A half a year later in 1977 the cause of the breakout was identified and given the name Legionella, while the accompanying disease was similarly named Legionnaire’s Disease.
A Dangerous, Gram-Negative Bacterium
Legionella is what is known as a gram-negative bacteria, which means a few different things: The “gram-negative” itself refers to the lack of crystalline violet stain found after applying the chemical process known as gram staining and instead, a cultured medium will turn bright magenta. Moreover, gram-negative strains do not have a thick shell of peptidoglycan surrounding their outer membrane as with gram-positive, which counter-intuitively makes them more resistant to common drugs and antibiotics. Therefore, gram-negative bacteria are responsible for more hospitalizations and subsequent reinfections. Other, more common infection strains include Salmonella, E. coli, and S. aureus.
Habitat and Pathogenesis
Legionella itself grows in stagnant, cool water. It typically lives inside of several species of amoebae, but will disperse outside the usual host in order to proliferate. From there the bacteria can be transmitted to the air via aerosols produced by dispersion of the water they inhabit, and that is how they are transmitted to humans. Once breathed in, they are swallowed by alveolar macrophages in the lungs- you can read into detail about them at https://www.frontiersin.org/articles/10.3389/fimmu.2019.02275/full -because it is here that Legionella are able replicate and further infect human beings. The result is Legionnaire’s disease, although younger, healthier individuals who contract this are more likely to suffer a mild case of pneumonia. Legionella is responsible for somewhere between 2 and 9 percent of all cases pneumonia acquired outside of the medical setting.
Legionella is Nasty- And Everywhere
Legionnaire’s disease itself is quite nasty. The typical symptoms experienced as a result of the disease are dry cough, fevers, chills, muscle-aches, headaches, nausea, and diarrhea. Over 6,000 cases of the disease are reported annually in the United States with the mortality rate in the low hundreds. As mentioned before, the bacteria responsible for this mayhem is found in stagnant cool water, meaning there is lots of potential exposure for those of use living in the modern world. Cooling towers, swimming pools, drinking fountains, dental equipment- even condensation found in air-conditioning units- these are all places where Legionella can hide. The water quality in places such as nursing homes and hospitals must especially be monitored, since those with older, weaker immune systems are most at risk.
Luckily, there are resources available for lowering the risk of exposure to Legionella. If you suspect that your home or business has any such water system that maybe mismanaged, there are professionals you can hire to conduct a risk assessment for legionella to see if it is indeed a potential threat. For businesses, any water system whether for casual use or intended for operations is a potential candidate for risk assessment. This could include any sort of simple hot/cold water system supplying taps/toilets, wet-air filtration/purification, water cooling apparatus used in manufacturing, and safety-showers/eye rinses. Generally, any water feature that can make a ‘splash,’ or is otherwise cooled for purposes of use can be a source of infection of legionella, as both these situations create airborne droplets of water; those known as ‘aerosols’.
Protect Your Employees
The Health and Safety at Work Act (HSWA), implemented 1974 in the UK, has since dramatically reduced the number of yearly casualties and injuries in the work place. Fatal injuries have dropped by 85% and non-fatal injuries have been reduced by 77%. It should not come as surprise that under the same law, employers, landlords and business owners alike are required to safeguard their engineered water systems from Legionella; a potentially fatal disease. Additionally, employers with five or more employees must record the details and results of any assessments or measures taken to manage the risk of a Legionella outbreak. How convenient is it, that HSWA was put in effect just two or three years before Legionella was discovered.