Integrating microbiology and modelling to determine the source of Campylobacter infection in the broiler house and develop interventions

Lead Research Organisation: University of Aberdeen
Department Name: Division of Applied Medicine

Abstract

Campylobacter is the largest cause of recognised bacterial gastroenteritis in the developed world. The 2009 reporting rates for Great Britain show more than 64 000 cases, an increase of 30% in Scotland and 14% in England & Wales on the previous year, that has continued into 2010. Because there is substantial under-reporting of campylobacteriosis, the actual number of cases in 2009 is likely to be closer to 450 000. Further, about 10% of reported cases are hospitalised. This rise is all the more disappointing because rates of infection with Campylobacter had been falling between 2000 and 2005. Molecular strain typing, by us and others, has identified that poultry is significantly the most important source of this infection with the most common types found in human beings also being the most common in chickens. Studies on retail poultry show a prevalence of Campylobacter in this meat of over 65% with the main routes of infection being eating improperly cooked meat or cross-contamination to uncooked foods. To reduce this burden of human disease, action must be taken to reduce Campylobacter loads in poultry and The Food Standards Agency, Defra and BBSRC have all identified this as a major priority. The FSA is considering targets for the reduction in levels of Campylobacter in raw chicken at retail, to be achieved by April 2015. The target will be set and achieved through stakeholder engagement and partnership working. Interventions in the poultry industry abroad have resulted in dramatic decreases in human infection rates. For example, in Iceland where freezing of positive carcasses is used, in New Zealand where interventions and regulations were introduced and in the USA where improved hygiene and the use of chlorine washes for carcasses has been implemented. However, UK industry has largely been unable to achieve reductions. Although strategies such as poultry vaccination are attractive in the longer term, more immediately it will be through informed biosecurity interventions on broiler farms that control is likely to be most readily achieved. Indeed UK producers widely recognise that where robust biosecurity remains unbreached, as for the valuable (grand)parent birds that are used to produce the eggs that hatch into broilers, then Campylobacter colonisation is uncommon. It is in the high throughput broiler production that colonisation regularly occurs and where novel biosecurity controls, as proposed here, could play an important role. Our previous studies of the sources of Campylobacter infection in humans not only identified the principal source as broiler chickens, it also identified that the distribution of Campylobacter strains found in humans and in the reservoirs of chicken, cattle, sheep, wild birds, pigs etc, were quite distinct with some strains common to several hosts. This proposal seeks to better understand the relative importance of the potential sources of Campylobacter in broilers by using a modelling approach. The hypothesis is that some Campylobacter strains and some Campylobacter reservoirs are much more important than others in this process and that it is only by quantitating their relative importance and their interaction with each other that it will be possible to robustly identify the sources of Campylobacter in the broiler house and hence introduce effective measures to prevent the colonisation of these birds during production. The findings will enable policy to be developed (e.g. code of practice) to define which control measures are most effective in keeping broiler houses Campylobacter free. This will strongly influence industry through improved farming practice.

Technical Summary

Poultry is the most important source of campylobacteriosis and over two-thirds of chicken at retail are contaminated by Campylobacter. A reduction in the Campylobacter loads and ideally a reduction in their prevalence in poultry at production would be the most effective measure for reducing human disease incidence. However to date, biosecurity has not proved to be entirely successful and it is thought that this may be due to the diversity of reservoirs that Campylobacter resides in. Our, and others, work has indicated that some Campylobacter strains and some Campylobacter reservoirs are probably much more important than others in this process and that it is only by quantitating their relative importance and their interaction with each other that it will be possible to robustly identify the sources of Campylobacter in the broiler house and hence introduce effective measures to prevent colonisation. It will be parameterised by data collected in the study. Up to eight Campylobacter strains will be selected from the top strains isolated from human cases and from chicken, cattle, sheep, pigs and wild birds. The efficacy of different strains to move from reservoir species (cattle, sheep, pigeon, chicken) to chickens will be quantitated to determine the dose response of each strain. The environmental survival of the Campylobacter strains will be estimated in a range of matrices associated with the broiler environment (faeces from cattle, sheep, pigeons and chickens; soil; water) and survival tested at two temperatures (4C and 15C) over a period of up to 3 months. This proposal will use an agent-based modelling approach, which identify how macroscale dynamics emerge from microscale interactions, to simulate the transmission of Campylobacter from the environment to the broiler house and potentially back to the environment on real farms. This will be used to quantify which interventions would be most likely to reduce broiler colonisation.

Planned Impact

This research aims to determine whether the simple and practical removal (or reduction) of animals or birds from the immediate vicinity of broiler houses will reduce broiler colonisation by the bacterial pathogen Campylobacter. This is of relevance to human health since the strains routinely isolated from retail chicken are the most predominant in causing human infection. Societal impact: Campylobacter is the most frequently recognised cause of gastrointestinal illness both in the UK and other developed countries. The majority of cases have symptoms that are not simply mild discomfort but are exceptionally debilitating and as such result in significant distress to both patient and relatives. There is an associated significant burden on the health care system both at GP level and from the 10% of hospitalisations. Further, there is extended loss of working days which has a major impact on the local and national economy. The cost of this has been estimated at £583M in 2008 in England and Wales. Studies have identified that reductions in retail broiler contamination would result in a reduced incidence of campylobacteriosis, with a concomitant reduction in cost to individuals and to the state. Stakeholder impact: Both FSA and Defra as the major policy stakeholders have agreed to join our discussion groups. Industrial impact: We will engage with industry throughout and have already obtained preliminary agreement to collaborate with one of the leading UK broiler producers, VION Food Group Ltd, who have agreed to attend progress meetings, to allow access to their broiler farms for sampling and to comment on the practicability in implementation of findings. Should the research proposal from co-I, Dr Sparks (Defra 'Assessment of the efficacy of on-farm biosecurity measures for controlling Campylobacter') proceed, then opportunities for joint project meetings with industry would be explored. Engagement with industry in the longer term will be in the development of'best working practices' for example through codes of practice, to implement those control measures which are identified as most effective in keeping broiler houses Campylobacter free. This will strongly influence the industry through improved farming practice. Dissemination: Articles will be submitted for publication to trade (Poultry World) and to high IF scientific journals, through press release and to the popular media and presented at academic (microbiological, modelling, poultry) and farming conferences.
 
Description Our previous studies of the sources of Campylobacter infection in humans not only identified the principal source as broiler chickens, it also identified that the distribution of Campylobacter strains found in humans and in the reservoirs of chicken, cattle, sheep, wild birds, pigs etc, were quite distinct with some strains common to several hosts. This research used a modelling approach to study whether some Campylobacter strains and some Campylobacter reservoirs are much more important than others in this process. This was achieved by quantitating their relative importance and their interaction with each other and this will allow informed and hopefully more effective measures to prevent the colonisation of these birds during production.
The studies have measured the ability of relevant strains to survive in the environment under different farming and weather conditions; this tells us how well they can survive once they have been excreted by farm animals in fields surrounding a broiler farm. This tells us what the infection pressure is on the broiler house from outside. The studies have measured how readily Campylobacter cells can move from surrounding areas to the broiler house, and what the environmental influences on this are. The studies measured the ability of relevant strains to colonise chickens and whether the animal source that they had come from influenced this. This tells us whether all strains are equally likely to colonise the broilers once they have entered the broiler house from outside. All of these microbiological measurements were input into different mathematical models to create an overview model of the whole pathway of Campylobacter moving from animals in surrounding farmland to colonising the broilers in the shed.
The results show that cattle or sheep farms situated in the close vicinity of broiler houses play an important role for colonisation; however, wild birds have an important contribution to colonisation of broilers only if they carry Campylobacter strains which are highly infective to chicken, periods of elevated rain will facilitate the spread of Campylobacter, hence increasing the colonisation risk. Infection pressure patterns on the broiler houses suggest the following putative mitigation strategies:
- placing live stock (e.g. cattle and sheep) at distances larger than 100 m will substantially reduce the infection pressure (i.e. at indistinguishable levels).
- removing high shedding ruminants substantially reduces the infection pressure if distance from the pastures to the broiler houses are >30 m.
- infection pressure due to wild birds is high, comparable or higher to that from ruminants due to the fact that birds can excrete faeces in the immediate proximity of the broiler houses; therefore birds scarers might be used to keep them at distance from the houses.
Exploitation Route We have a much improved understanding of the differences in colonization of broilers by different strains, both from a biological and mathematical perspectives. This, along with archived microbiological samples is a resource that can be used to further understand the underlying genetic and possibly physiological basis of why different Campylobacter strains have different host specificities.
Sectors Agriculture, Food and Drink,Environment,Healthcare

 
Description Scottish Health Protection Network: Campyobacter
Geographic Reach National 
Policy Influence Type Membership of a guideline committee
 
Description BBSRC/FSA/DEFR Joint call on Campylobacter research: Integrating Microbiology and modelling to determine the source of Campylobacter
Amount £323,441 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 02/2012 
End 02/2014
 
Description Curtin University - Aberdeen University Collaboration
Amount £70,000 (GBP)
Organisation Curtin University 
Sector Academic/University
Country Australia
Start 02/2017 
End 01/2020
 
Description PhD Scholarship from Mutah University, Jordan
Amount £90,000 (GBP)
Organisation Mutah University, Jordan 
Sector Academic/University
Country Jordan
Start 10/2017 
End 09/2020
 
Description RESAS Innovation tender
Amount £190,409 (GBP)
Organisation Government of Scotland 
Department Scottish Government Rural and Environment Science and Analytical Services Division (RESAS)
Sector Public
Country United Kingdom
Start 04/2016 
End 03/2017
 
Description Research
Amount £229,972 (GBP)
Organisation Government of Scotland 
Department Food Standards Agency (FSA), Scotland
Sector Public
Country United Kingdom
Start 11/2015 
End 03/2017
 
Description University of Aberdeen Elphinstone PhD Scholarship
Amount £70,000 (GBP)
Organisation University of Aberdeen 
Sector Academic/University
Country United Kingdom
Start 02/2017 
End 01/2020
 
Title Archived microbiological samples 
Description Archived microbiological samples is a resource that will be used to further understand the underlying genetic and possibly physiological basis of why different Campylobacter strains have different host specificities. 
Type Of Material Biological samples 
Provided To Others? No  
Impact n/a 
 
Title BBSRC models 
Description The sub and main models developed here can be modified to understand the survival and transmission of other pathogens, such as E.coli O157 or Listeria. 
Type Of Material Computer model/algorithm 
Provided To Others? No  
Impact n/a 
 
Description Collaboration with MRC project 
Organisation University of Liverpool
Department School of Medicine Liverpool
Country United Kingdom 
Sector Academic/University 
PI Contribution Provision of intellectual information on the role of farm animals contributing Campylobacter to the countryside and the survival of Campylobacter in the countryside.
Collaborator Contribution N/A
Impact None as yet
Start Year 2012
 
Description "Farm to Fork or There and Back Again" Hutton Institute Dundee, April 2013 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Discussed how the research could lead on to further studies.

Lead to an invited seminar in 2014
Year(s) Of Engagement Activity 2013
 
Description "Kitchen Killers" MayFest 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Public engagement event to stimulate understanding in general public of the infection hazards in the home and at leisure. Stimulated much discussion about the safety of the food chain

Radio presentation made by member of staff on 'life as a microbiologist'
Year(s) Of Engagement Activity 2014
 
Description Acting Together on Campylobacter. June 2014 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Enabled FSA to encourage UK broiler industry and retailers to commit to reducing Campylobacter loads on retail chicken by 2015

Useful meeting with broiler industry representatives which will facilitate future collaboration
Year(s) Of Engagement Activity 2014
 
Description Meeting with Poultry producers 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact To discuss preliminary findings on the control of sources of colonisation of broilers on farms

Encouragement to proceed with the study as other methods of control were proving ineffectual
Year(s) Of Engagement Activity 2012,2013,2014
 
Description Presentation to Roslin Inst Edinburgh 25th October 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact A presentation to the BBSRC Roslin Institute in Edinburgh entitled: A pot-pourri of GI pathogen anecdotes: Campylobacter, STEC and Anisakiasis
Year(s) Of Engagement Activity 2016
 
Description Scottish Health Protection Network (SHPN) - Gastrointestinal Infections and Zoonoses 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Remit is to provide a forum for discussion and information sharing on Campylobacter between partner organisations in Scotland to protect public health by identifying key transmission routes and implementing effective interventions.
Year(s) Of Engagement Activity 2016
 
Description Talk to Public Health Aberdeen, 2012 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Health professionals
Results and Impact Consultants in Public Health attended a talk on the research being carried out on gastrointestinal pathogens

This took place in October 2012 - the only additional impact was being asked back to give a talk specifically on Campylobacter
Year(s) Of Engagement Activity 2012