Legionella pneumophila and protozoan hosts: Implications for the control of hospital and potable water systems

Muhammad Atif Nisar, Kirstin E. Ross, Melissa H. Brown, Richard Bentham, Harriet Whiley

Research output: Contribution to journalReview articlepeer-review

30 Citations (Scopus)
37 Downloads (Pure)


Legionella pneumophila is an opportunistic waterborne pathogen of public health concern. It is the causative agent of Legionnaires’ disease (LD) and Pontiac fever and is ubiquitous in manufactured water systems, where protozoan hosts and complex microbial communities provide protection from disinfection procedures. This review collates the literature describing interactions between L. pneumophila and protozoan hosts in hospital and municipal potable water distribution systems. The effectiveness of currently available water disinfection protocols to control L. pneumophila and its protozoan hosts is explored. The studies identified in this systematic literature review demonstrated the failure of common disinfection procedures to achieve long term elimination of L. pneumophila and protozoan hosts from potable water. It has been demonstrated that protozoan hosts facilitate the intracellular replication and packaging of viable L. pneumophila in infectious vesicles; whereas, cyst-forming protozoans provide protection from prolonged environmental stress. Disinfection procedures and protozoan hosts also facilitate biogenesis of viable but non-culturable (VBNC) L. pneumophila which have been shown to be highly resistant to many water disinfection protocols. In conclusion, a better understanding of L. pneumophila-protozoan interactions and the structure of complex microbial biofilms is required for the improved management of L. pneumophila and the prevention of LD.

Original languageEnglish
Article number286
Number of pages23
Issue number4
Publication statusPublished - 15 Apr 2020

Bibliographical note

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).


  • Acanthamoeba
  • Hospital water
  • Legionella pneumophila
  • Legionellosis
  • Potable water
  • Protozoa
  • Vermamoeba
  • Water disinfection


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