From chicken to Commission - Salmonella infection in table egg production Rob Davies, Juan Carrique-Mas VLA Weybridge Acknowledgements:Defra and EC Funding

Agenda  Surveillance trends  Consideration of VLA projects:  Improved sampling for better detection  Decontamination of persistently infected farms  Salmonella vaccination  Translating findings into policy

Enteritidis Salmonella Enteritidis and Typhimurium in chickens in GB End treatment broiler parents SE Vaccination layers Live MD Vaccines SE vaccination breeders 9R Auxotrophic Vaccines

VLA Projects  Preliminary studies (1998) – ad-hoc investigations, intensive sampling, sensitive culture, close observation,  OZO317 ( ) –longitudinal studies, sampling comparisons, existing best practice, egg contamination  OZO321 ( ) – wider studies, quantification, physiology and infectivity of isolates, EU survey follow-up  OZO325 ( ) – multi-disciplinary (Bacteriology, Epidemiology, Modelling, Parasitology) (+Bristol Uni.,CSL, NE, ADAS, BEIC,[Moredun, Newcastle Uni.]) - focus on monitoring, control, interventions and education

Main Findings - OZO321  SE quantification - high numbers in rodent faeces, flies, feeding systems, drinkers  Live vaccines did not reduce SE persistence  Uni.Bristol challenge exposure confirmed drinkers as high risk – despite vaccination  No difference in physiology or virulence genes according to persistence  EU survey follow-up investigations showed similar problems in cage and worse in non-cage than original cohort  Multiple flock infection per holding suggested 20% under- estimate of holding prevalence by EU survey

Need for Improved Sampling: Lion Code Farms sampled in Research Projects

Main Findings so far - OZO325  VLA sampling > EU survey> EU monitoring  Pooling eggs in 40s retains sensitivity – no advantage of Ferrioxamine E  Heat treatment insufficient for red mites  Fly treatments usually too late  Formalin disinfection by specialist very successful  Chlorcresol/F.G.Q. combination good farmer option  Infected rodents undermine any control programme  Effective rodent control – undetectable infection in flocks

After depopulation Post-washing Post heat treatment Post-formalin treatment Heat & formalin treatment of a large SE-contaminated cage house

OZO325 cont.  300-bird PMs may be negative from positive flocks  Significant contamination of eggs – especially small and non-cage  Different response to various vaccination programmes in field and controlled challenge studies  Multiple vaccine administration errors identified – but ?significance  Serological tests for killed vaccine OK  Bacteriological tests for live vaccine in water OK  Problems with assessing 2 (of 3) live vaccines in faeces  Cumulative findings consistent, support international literature and risk factors from EU survey

Studies of Salmonella in spent hens (300), environment and eggs

Proportion of flocks with SE before and after change of vaccine Transition to vaccineTransition away from vaccine V1 V2 V3 V4 V5 No vaccine Transition to vaccineTransition away from vaccine

Use of Results  Defra COPs  SVS/VLA field staff Instructions/training  NCP Stakeholder WGs  Lion Code revisions/BEIC Road shows  Consultant – DG SANCO – Zoonoses WG/ EU training initiatives, Community Hygiene Guide  Consultant – EFSA – survey design and analyses  Consultant – ISO/CRL Salmonella – sampling/sample preparation/testing  Commercial – egg producers (BEIC, UKEPRA, FREPA, direct advice), vaccine manufacturers, specialist poultry vet.s

Conclusions  Intensive longitudinal – ‘intervention-observation’ studies provide detailed evidence and experience  Layer problems result from insensitive monitoring and over-reliance on vaccination  Rodents are main reservoir of Salmonella infection  Other vectors (e.g. flies, litter beetles) may be substantially implicated if high populations  Cleaning, disinfection, pest control problematic and expensive for cages – but can be done  More work on vaccination programmes and CE combinations in progress  Road shows have raised awareness – follow-up in Autumn