The ecology of protist associated human pathogens

Lead Research Organisation: University of Warwick
Department Name: Biological Sciences


The survival of human pathogens in the environment is an under studied area, and it is often assumed that pathogenic bacteria die or become senescent outside mammalian or vertebrate hosts. However, it is becoming clear that human pathogens form associations with protozoa which are single celled microorganisms found in all natural environments that are more closely related to multicellular organisms than to bacteria. They play a key role in microbial food webs, grazing on bacteria and recycling nutrients. Protozoa also interact with bacteria and viruses in more complex ways. Species of the genus Acanthamoeba are responsible for a serious eye infection, amoebic keratitis, and more rarely infections of the skin and central nervous system. Acanthamoebae have also been shown to harbour human pathogens including Legionella sp., Chlamydia sp., Mycobacterium sp., Listeria sp., and the giant virus, Mimivirus, which is an emerging human pathogen. Preliminary research demonstrated an abundant population of acanthamoebae in treated sewage sludge, >1 million tons of which are disposed of to land in the UK each year. One isolate harboured Mimivirus, an emerging human pathogen and the largest known virus which has only been isolated twice before. Further soil and sediment isolates harboured novel Chlamydia and Legionella sp.. The proposed research seeks to investigate human pathogens in soil and aquatic sediments associated with protozoa, and will assess the impacts of sewage sludge and waste water treatment effluent on the ecology of amoeba associated pathogens. Culture dependent and independent methods will be used to assess abundance and diversity of amoebae and associated bacterial and viral pathogens. High throughput sequencing will be used to assess diversity of associated mycobacterial pathogens and compare this to their diversity in bulk soil / sediment. Previous work in this area is highly fragmented and this study would be one of the first to try and elucidate the abundance and diversity of a range of amoeba associated pathogens in different polluted and unpolluted environments.


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Description We detected species of mycobacteria residing inside amoebae and established these were viable. Although no M.bovis was found many cells of Acanthamoeba contained chlamydia and legionella species. This is interesting observation due to the large numbers of positives and needs further investigation if any of these strains could be pathogenic to humans.
Exploitation Route We are finishing off publications and we believe data will be useful for further studies on ecology of pathogens particularly reservoirs of chlamydia in the environment.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Environment,Healthcare,Pharmaceuticals and Medical Biotechnology

Description SEVENTH FRAMEWORK PROGRAMME EU Initial Training Network
Amount € 320,000 (EUR)
Funding ID 289285 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 01/2012 
End 12/2015
Description ? Met Lee Slater (Defra Senior Policy advisor on AMR and the environment) for 2.5 hours to discuss AMR in the environment. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Discussion with Defra Senior Policy Advisor on AMR in the environment
Year(s) Of Engagement Activity 2017
Description Public Science Evening 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Presentation given at an evening event on the Microbiome event to inform the public about the importance of bacteria in the human gut, in the soil and in the bioremediation of polluted environments.
Year(s) Of Engagement Activity 2017
Description Public science evening 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact At the public science evening "The microbes on us and around us: We can't see them but can't live without them" hold at the university, the general public was introduced to the issue of AMR dissemination in the environment through oral and poster presentations followed by discussion in small groups with member of the team working on AMR. The Department reported an increased interest and understanding in the related subject area.
Year(s) Of Engagement Activity 2017