Management of Legionella in Water Systems

I am currently reading an excellent book called “Management of Legionella in Water Systems” and I would recommend it to anyone in the Legionella industry.

I thought I would share a few extracts from the book in the hope that it encourages you to learn more (or even buy the book).


“The ecology of L. pneumophila is directly linked to that of protozoa, whose primary habitat is biofilm (Declerck, 2010). A biofilm is a community of microorganisms within a self-produced hydrated gel matrix attached to moist soil, sediment, and other solid surfaces that accumulates organic and inorganic material (Characklis and Marshall, 1990). Biofilms typically form on all moist surfaces, including engineered surfaces such as pipes, tanks, appurtenances, filters, and gaskets—virtually everything that contacts water. Biofilm communities growing on pipes can include bacteria/archaea (including round, rod-shaped, filamentous, and appendaged forms), fungi, and higher organisms such as amoebae, ciliates, nematodes, larvae, and crustaceans. The pipe material can exert a strong influence on the composition and activity of the biofilm’s microbial community. Both surface materials and temperature influence the complex interactions among Legionella, host amoebae, and biofilm community members.

Biofilm and Legionella growth can also be enhanced by water age, which depends on the building type and use, occupancy, and water use. Indeed, the water residing in premise plumbing has a much wider age distribution than the water entering a home from the distribution system (NRC, 2006).”


“Serological testing of blood donors indicates that exposure to Legionella may be higher than generally appreciated, with seroprevalence ranging between 4 and 22 percent and up to approximately 40 percent in some cities or among those with high-risk occupations (Borella et al., 2008; Coniglio et al., 2009; Nadaraja et al., 1987; Rudbeck et al., 2008; Valciņa et al., 2015).

It is unclear why patients develop Pontiac fever rather than pneumonia; consequently, the pathogenesis of the disease remains unclear. Several pathways for Pontiac fever have been hypothesized, including bacterial toxins, allergic responses, and exposure and reaction to Legionella-carrying amoebae (Edelstein, 2007). A self-limiting disease, Pontiac fever does not require treatment with antibiotic therapy, leading some to hypothesize that the disease is not directly related to infection by these bacteria. At the same time, there have been outbreaks where patients who develop Pontiac fever have positive urinary antigen testing, suggesting that the disease is associated with ingestion or inhalation of either live or dead microorganisms (Burnsed, 2007). Mechanism of exposure may also play a role, as some recreational outbreaks have been linked to both Legionella pneumonia and Pontiac fever, whereas others are tied only to Pontiac fever (Euser et al., 2010; Leoni et al., 2018).

The Urinary Antigen Test can remain positive for months after an infection, particularly in immunosuppressed patient populations (Kashuba and Ballow, 1996; Kohler et al., 1984; Munoz et al.,2009).”

Legionella bacteria

“Depending on its environment, L. pneumophila can differentiate between replicative, transmissive, filamentous, mature infectious forms, and viable-but-not-culturable-like (VBNC-like) cells. L. pneumophila cells obtained from solid media are a mix of replicating, transmissive, and filamentous cell types, whereas more homogenous cell populations can be isolated from broth cultures. Each specialized cell type differs in its capacity to infect host cells and tolerate antibiotics, biocides, and other environmental stresses.”

This excellent book is certainly full of good ideas, facts and knowledge about the subject of Legionella and should therefore be a must read for all involved in the industry.

You can download the book here by clicking on this link.

If you want to discuss the application of the information above to your systems then contact Collaton Consultancy via: or phone on +44 (0)7958 124563.

Collaton Consultancy Limited are expert Legionella consultants working for both water treatment companies and end users alike, Expert Witness services are also offered should a legal case arise. If you have any specific issues relating to the above or you would like help then contact Collaton Consultancy Limited

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