A dynamic approach to reducing high Salmonella prevalence

International research conducted by the European Food Safety Authority (EFSA) has identified that the UK’s prevalence of Salmonella in both breeding and finisher pigs is higher than the EU average. In the first of three articles, Pig World explores a DEFRA-funded research project – coined R8 – that the Animal Health and Veterinary Laboratories Agency (AHVLA) is delivering, to understand more about the issue facing the industry and effective ways of controlling Salmonella on farm

The problem of Salmonella isn’t a new issue for pig producers, but the level of incidence is a cause for concern, and shouldn’t be overlooked. It’s particularly pertinent given that the EU has been alluding to tighter and stricter Salmonella control measures that could be enforced on farm.

“The international research and the possibility of a national control plan set us on a path to use this research opportunity to find out how Salmonella could be effectively and realistically controlled on pig farms,” AHVLA epidemiologist Dr Richard Smith says. “The merits of various control methods have been debated for years. But it’s important to reiterate that Salmonella is a good indicator species for other health concerns and highlights where improvements to biosecurity could be made. If Salmonella is present, it’s likely that other organisms will also be there.”

Although the R8 project is principally based around Salmonella prevention methods, it’s widely recognised that if the bacteria is controlled, there could be added on-farm benefits.

“There’s huge concern in the industry about porcine epidemic diarrhoea (PED) and African swine fever, so this is as good a time as any for farmers to act on issues of biosecurity and disease prevention,” Dr Smith says. “Previous research and recommendations into Salmonella have often failed to take into account the variation between units and typically recommend a one-size-fits-all approach.

“However, we acknowledge that units are different and therefore the aim of the R8 project is to identify a number of suitable control points and interventions.”

The AHVLA team is being supported by BPEX and ADAS to ensure that the research and subsequent recommendations are relevant to UK producers.

“The R8 project has six key research objectives that we recognise will be of significant value in the battle against Salmonella,” BPEX veterinary programme manager Helen Clarke says, “and once the project is completed we’ll have a toolbox of tactics and advice that will have been validated and that we can share with confidence.”

Research objective one: Low prevalence units

The first objective is to understand the measures that have been implemented on units that have had consistently low levels of Salmonella historically.

“We’re currently benchmarking 19 persistently low-prevalence farms against 38 control units representing a proportion of the wider pig industry,” Dr Smith says. “By the end of the exercise we want to fully understand what these farms are doing differently, and clarify how they achieve a consistently low level of Salmonella.

“We’ll also have the opportunity to go into the abattoirs and follow the batches of pigs through the supply chain. So not only are we taking swabs at farm level, we’re also trying to ascertain the most effective ways to take samples in the abattoir so that we can cross-reference bacterial strains found on the farms and carcases.”

Research objective two: On-farm ‘interventions’

The second objective covers three different types of ‘interventions’ on farm. The first intervention is the movement of outdoor sites.

“We want to understand the benefits that come from moving outdoor herds to new ground,” Dr Smith says. “It’s our understanding that land gets very contaminated over time. We therefore need to establish what the cost-benefit trade-off is between pigs staying healthy and clean, and the labour cost of moving pigs more frequently.”

The second intervention, vaccination, was monitored previously on a small scale on four units, but a statistically validated controlled trial is now needed.

“We’re going to be following vaccinated and non-vaccinated farms and collecting data on costs and performance,” Dr Smith says.

The final intervention is improving cleaning and disinfection of finisher housing.

“This is something all units should be doing,” he adds. “We’ll complement the cleaning teams by sending in experts from Natural England and AHVLA to monitor the cleaning process and control any rodent problems, as well as training the farm staff. This will give the intervention a greater chance of working.”

Research objective three: Web-based biosafety tool

The third strand of the R8 research is the BPEX Farm Tool, which was initially created to help farmers identify problems in relation to Salmonella. ADAS has been leading on adapting this to produce a web-based Biosafety Assessment. It will include training exercises and may also provide helpful ideas along with links to further guidance.

Research objective four: Disinfectants and detergents

A number of tests on a large panel of disinfectants and detergents will be carried out so that authenticated recommendations can be made.

“Through the disinfection trials, we’re already building up a wealth of evidence about products,” Dr Smith says. “This allows us to distribute advice around the use of disinfectants for example, as many of the boot dips we’ve tested from farms haven’t had the ability to kill Salmonella.”

Research objective five: Pig movements

Number five on the list is to characterise potential “risky” behaviour identified from eAML2 pig movement data.

“The research is still in the early stages, but it’s helped us to highlight certain key movement characteristics,” Dr Smith explained. “For example, the number of suppliers used by a farm and supplying more than 200 pigs a year had a key impact on the risk of disease breakdown. We’re still working on this at the moment, but the idea is to create a Salmonella transmission model to test the effect of changes to how pigs are supplied.”

Research objective six: Communication

The potential of this research project is limited without outreach and that’s what’s behind the sixth objective. With the help of BPEX and dedicated roadshows, engagement will be made with farmers and vets about changing the Salmonella status of farms.

Next steps
Through these six objectives it’s hoped the industry and related stakeholders recognise the value and importance of this holistic approach to Salmonella control.

“No matter what the outcome of European intervention is, the pig industry needs to recognise that change can deliver results,” Dr Smith says. “The prevalence of Salmonella in poultry and turkey farms has been significantly reduced by applying approaches similar to R8.

“As an industry, we’re now faced with the fact that attribution studies are proving that a larger proportion of human cases of salmonella are being traced back to pork consumption.

“The industry needs to move ahead of legislation and embrace best practice to reduce Salmonella in pigs before it becomes an issue.”

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