Trial underway to get Salmonella vaccine licensed for UK

A research project funded by DEFRA and delivered by the Animal Health and Veterinary Laboratories Agency (AHVLA) has been commissioned in order to understand more about the issues facing the industry from Salmonella.

“When it comes to controlling Salmonella there’s no ‘golden bullet’,” acknowledges BPEX welfare projects coordinator Georgina Crayford. “The R8 Project encompasses six research objectives that cover a range of on-farm controls, something previous research hasn’t always considered.

“There’s no one-size-fits-all approach, and this project is centred on a toolbox of control measures that will work together to reduce Salmonella levels on farm.”

As part of the project, vaccination is one on-farm intervention that’s under the spotlight.

“A Salmonella vaccination is currently available; however it’s not licensed for use in the UK,” explains AHVLA Salmonella specialist Dr Rob Davies. “To administer it, a vet has to get a special licence for each individual batch of vaccine, which is agreed by the Veterinary Medicines Directive (VMD); this can be a complex procedure.”

This has ultimately resulted in the vaccine only being used in serious outbreaks, despite previous case study projects, undertaken by the AHVLA, showing consistent reductions in Salmonella levels and improvements in the health of the pigs weaned following vaccination.

“In parallel, several reports from pig vets also showed clinical improvements,” Dr Davies adds. “As a result of these case study projects, the effectiveness of vaccination will be validated through the use of control farms within the R8 project and a cost-benefit analysis for its use will be carried out. This fully controlled study has also been approved by an Animal Test Certificate and so will be compliant with the VMD standards.

“At the end of the project the company supplying the vaccine, IDT, should have the data to go to the VMD to get the product licenced for use in the UK.”

It’s hoped that farmers and vets will then consider using the vaccine routinely to prevent Salmonella, rather than delay until there is a sizeable outbreak on farm.

“We’re confident that the trial will confirm what we already know,” Dr Davies says. “Our objective is to demonstrate that vaccinating sows allows them to produce antibodies in the colostrum that will protect piglets through natural immunity.

“And then, as long as these piglets are not exposed to high Salmonella pressure after weaning, they should carry through to slaughter with no, or much lower, levels of Salmonella compared to unvaccinated herds.”

The vaccination programme, which commences in October, will be made up of eight vaccinated herds and eight control herds. Each unit will be matched with a very similar control herd and they will all be assessed for regular and monophasic Salmonella typhimurium.

“The sows and gilts will be vaccinated one month before farrowing and injected with a booster injection three weeks before each subsequent litter,” Dr Davies explains. “ADAS will be recording and monitoring production, cost and herd health data from the study.

“We hope that this data will demonstrate that the vaccine can pay for itself through both health and productivity improvements. The farms will be monitored for 18 months. Results from the study should be available by summer 2016.”

If you’re interested in becoming involved in the vaccination trials, contact Dr Richard Smith via email at:

richard.p.smith@ahvla.gsi.gov.uk

Common strain could be causing more diarrhoea

Monophasic Salmonella typhimurium first appeared in pigs in the UK in 2007, but has increased in prevalence in recent years to become the most common strain of Salmonella in pigs, according to BPEX’s Georgina Crayford.

“Moreover, pigs have been identified as the main reservoir for the strain, which can then spread to infect cattle, poultry, horses and pets, as well as people,” she adds. “Although it’s only anecdotal evidence, unlike traditional strains, it’s believed this monophasic strain is causing more severe clinical signs in pigs.”

In the past pigs, particularly weaners, may have had bouts of diarrhoea and gastroenteritis, but farmers may not have made the link to Salmonella infections.

“Now we suspect that this strain is increasingly responsible for these clinical signs,” Miss Crayford says. “We’re keen to encourage farmers to consider Salmonella as the cause, avoiding unnecessary treatments for other ailments that might not be responsible.”

BPEX also supports post-farm gate measures to minimise the risk of exposure of humans. While it’s important that on-farm interventions are adhered to, the wider supply chain also has an important role to play in controlling Salmonella.

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