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CDRP meeting August 2011

Campylobacteriosis : Identifying the source of human infection and environmental contamination Nigel French, Jonathan Marshall m EpiLab , Hopkirk Research Institute, Massey University. CDRP meeting August 2011. m EpiLab : Molecular Epidemiology and Public Health Laboratory. We work on:

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CDRP meeting August 2011

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  1. Campylobacteriosis: Identifying the source of human infection and environmental contaminationNigel French, Jonathan MarshallmEpiLab, Hopkirk Research Institute, Massey University. CDRP meeting August 2011

  2. mEpiLab:Molecular Epidemiology and Public Health Laboratory We work on: Food safety (Veterinary) Public Health Surveillance Molecular epidemiology of zoonoses Campylobacter VTEC (E. coli O157) Cryptosporidium, Giardia Leptospira Salmonella ...others http://mepilab.massey.ac.nz

  3. Campylobacter research in the Hopkirk Institute • Source attribution • Pathway modelling • Food, water, environment • Molecular epidemiology • Spatial modelling • Intervention studies • Assessing industry interventions • Controlled trials • Transmission modelling • Evolutionary studies • Full genome sequencing • Models essential for all the above

  4. Campylobacteriosis Source: Olsen et al Campylobacter. 3rd ed. Washington DC: ASM Press; 2008 .

  5. Campylobacter from space... Google Earth 2000-10 110,000 cases C. Jewell

  6. Interventions in poultry industry demanded in 2006 2006

  7. Chicken – confusing / conflicting evidence? Ikram 1994, New Zealand Campylobacter study

  8. Approaches to ‘source attribution’ • (Analytical) epidemiology • Population-based epidemiological studies • Simulation modelling / Risk assessment • Molecular epidemiology • Microbial subtyping / source tracking • Applying molecular tools, population genetics and epidemiological modelling to inform public health policy • Mostly NZFSA funded

  9. Manawatu study 2005-2011 Sentinel site (5-6 yrs) – required good collaboration Identify genotypes common to particular sources Identify outbreaks / clusters of cases Modelling Source attribution Risk factors / transmission pathways

  10. Multi Locus Sequence TypingMLST Sequence highly conserved genes 7 housekeeping genes Used to define: ST = sequence type – unique pattern of 7 genes Clonal complex = group of related STs Website: Oxford University http://campylobacter.mlst.net

  11. Host associated sequence types in NZ ST 474 Poultry associated Ruminant associated

  12. Need for good epidemiological data EpiSurv, PHU Spatial model

  13. Source attribution • Source attribution – used 4 approaches • Proportional similarity • Simple, area of overlap • Dutch model • Simple assignment • Hald model • Complex, epidemiology based • Island model • Complex, population genetics based

  14. Proportion of human campylobacteriosis cases attributable to each source: comparing, from left to right, the Dutch (I), modified Hald (II) and asymmetric island model (III). Error bars represent 95% confidence / credible intervals. Source attribution (Mullner et al) Need for more information on other sources

  15. …2006-2009, ... 2010-2012

  16. Relationship between campylobacteriosis notifications and hospitalisations (A. Sears) Data Sources: ESR Ltd notification data; NZHIS hospitalisation data (filtered)

  17. Modelling post intervention change in attribution N=800+ human cases Poultry Bovine Ovine Dynamic Hald model

  18. The changing epidemiology of campylobacteriosis in New Zealand % Reduction in case rates most marked in urban adults... ...and least in rural children.

  19. Recent trends Rates: Number of cases per 1000 people Year

  20. Models showed strong correlation with density of dairy cattle in rural areas No significant relationship with sheep density but strongly related to dairying Transmission pathways………….?

  21. New tool for cluster detectionModelling case notifications to identify clusters/outbreaks Outbreak probability >80% 50-80% 10-<50% 61 events 2001-2007 Water supply zones

  22. Tararua outbreak in 2008 ST 190 Water flow Episurv

  23. Surface water sampling Dairy=227,658 Beef=181,196 Manawatu – farmland and bush

  24. Manawatū River

  25. Prevalence of Campylobacter spp.

  26. Numbers of campylobacter in water samples % occasions when samples countable at each level

  27. Campylobacterin Manawatu rivers Flow Month of year More likely to recover ruminant strains during high flow

  28. Ruminant

  29. Source attribution: water • Most isolates from water are associated with wildlife – even in dairy catchments at base flow • But.... cattle and sheep isolates more likely to be associated with human infection Water birds Sheep Cattle

  30. Time series in urban and rural areas High density dairying Poultry intervention Urban 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

  31. Seasonality and dairy density Urban High dairy rural

  32. Dairy herd modelling J. Marshall

  33. Source attribution CDRP project expanded database from a much wider range of sources >4000 isolates Urban ducks and passerines, cats and dogs Now have information on many sources...

  34. Summary Improved understanding of epidemiology Source attribution modelling Tools advanced in recent years Applied to Campylobacter in NZ Food, particularly poultry, most important source 50% decline in human cases 2007-8 Environmental exposures less well defined Campy in water predominantly wild bird origin (base flow), but ruminant strains more ‘virulent’ Control of ruminant-acquired infections Direct contact pre-school children at calving Modelling key part of all research activities Still a lot to do!

  35. Ongoing water safety/quality projects • MoH • Waterborne protozoa • Metagenomics • Allan Wilson Centre • DoC campground water quality • PhD students • GIS- based catchment assessments • Water bird strains

  36. Acknowledgements CDRP team NIWA – Graham McBride, Sandy Elliot ESR – Rob Lake, Beverley Horn, Andrew Ball NZFSA – Peter van de Logt MfE Amanda Hunt Staff – lecturers, RAs Dr Simon Spencer, Dr Jonathan Marshall, Dr Patrick Biggs Lab team: Rebecca Pattison, RukhshanaAkhter, Errol Kwan, Lynn Rogers, Isabel Li, Jim Learmonth, Anthony Pita, Sarah Moore, Angie Reynolds, Neville Haack PhD students Vathsala Mohan Masters students TuiShadbolt, Ann Sears MidCentral Public Health - Dr Jill McKenzie and team MedLab Central ESR - SharlaMcTavish, Elaine Moriarty , Stephen On, Ruth Pirie AgResearch – Grant Hotter Michael Baker Robert Sanson , Massey – Dr Barbara Holland, Dr Geoff Jones, Dr Alasdair Noble, Prof Martin Hazelton Allan Wilson Centre Undergraduate student Jeffrey Ling Industry – PIANZ, meat plants CDRP, NZFSA, MoH, FRST, Royal Society Marsden and Industry funding

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