Biosecurity matters in minimising disease risk

Stuart Lumb reports from BPEX’s recent biosecurity conference at York, where expert speakers discussed strategies to keep African swine fever (ASF) and porcine epidemic diarrhoea virus (PEDv) out of the UK

Being a pig producer has never been for the faint hearted and we seem to be constantly battling disease in one form or another. PMWS and PDNS, that nearly bankrupted many producers, have been laid to rest thanks to some very effective vaccines, but now the black clouds are gathering again in the shape of not one, but two “nasties”, ASF and PEDv.

In view of these disease threats, BPEX organised three regional biosecurity conferences to raise industry awareness, but sadly two didn’t take place due to a lack of support, which should be a serious concern for the whole pig sector.

Neither ASF nor PEDv have been found in the UK yet, and the conference focused on how to prevent these diseases being introduced and how to recognise them early, should they enter. And it’s worth noting that the virulent form of PED, that has spread in Asia and North America, isn’t even a notifiable disease in the UK at the time of writing.

Susanna Williamson works for the Animal and Plant Health Agency (APHA) and is based at Bury St Edmunds. She leads the DEFRA-funded Scanning Surveillance for Pig Diseases in England and Wales project, and has been Veterinary Lead of the Pig Expert Group since April 2014.

Dr Williamson, along with colleagues in the Pig Expert Group and APHA’s International Disease Monitoring Team carry out “horizon scanning” which involves looking out for emerging trends and disease threats on a worldwide basis, not just in the UK. This is immensely important work and can be likened to the Fylingdales Early Warning Radar station in North Yorkshire that would give warning of a nuclear attack on the UK.

APHA relies tremendously on vets in practice reporting anything unusual, severe or unresponsive, and they, in turn, rely on producers getting in touch promptly when problems arise. Once APHA’s veterinary investigation officers hear about a potential issue, they can decide on the best diagnostic samples, which may be a batch of three typically affected freshly dead pigs, or samples collected on farm.

For diagnosis of PEDv, submission of faeces or intestinal contents is preferable to swabs, and BPEX is already funding extra testing for PEDv on farms with outbreaks of diarrhoea.

Good communication is vital for this surveillance system to work effectively, and Dr Williamson made the point that the APHA did not share the identity of farms on which endemic (non-notifiable) diseases had been diagnosed through testing procedures.

African swine fever
ASF, unlike PEDv, is a notifiable disease, which means that there’s a legal requirement to report suspicion of disease to APHA. The meeting was told the big threat from ASF was coming from Russia and Belarus, both of which border the Baltic Countries and Poland.

“Poland is very significant as large numbers of 30kg pigs are transported there from Denmark and the trucks naturally have to return home,” Dr Williamson said. “The Danes have invested in huge truck washes at the Danish border and hauliers have to follow very strict biosecurity protocols, but even so, ASF must be giving concern to Danish vets as winter approaches; viruses just love cold, damp weather.”

The major factor spreading ASF in North-eastern Europe is the fact that wild boar can become infected and spread the virus within their populations. This spread is exacerbated when they scavenge dead infected pigs. Wild boar don’t respect national borders, and can then pass on infection to backyard pigs, which are often kept in conditions that mean they’re not isolated from their feral cousins.

A particular concern is that ASF will become endemic in the wild boar population, which is significant in Eastern Europe; reports suggest up to 600,000 wild boar are shot by hunters in Germany each year.

Another factor worth noting is that many UK pig unit staff have family links in ASF-infected countries and there’s a risk that infected pork products may get brought back to the UK. If staff take their food into the pig unit, this creates a risk of pigs eating these products (which is illegal), even if it occurs accidentally.

Feeding any raw or cooked catering waste to pigs, including waste from household kitchens, is illegal and BPEX has produced warning posters in specific languages reminding farm staff of this. Some enlightened employers have even started providing lunch for their unit staff. Provision of overalls and footwear that remains on the farm also reduces the risk from returning staff.

As far as diagnosing pigs with ASF is concerned, they will typically have high fevers, huddle, become lethargic, lose their appetite and many will die after a few days. Furthermore, some may die suddenly. Red-purple skin blotching may also be seen, haemorrhages may occur and pigs could have bloody diarrhoea.

Farmers and vets seeing unexplained clinical signs and who are suspicious of ASF should report them to their local APHA office without delay.

Porcine epidemic diarrhoea
The former head of R&D at BPEX, Derek Armstrong, recently drafted a contingency plan for an industry response to the threat of PEDv. He didn’t pull any punches, bluntly stating that PEDv has bankrupted producers in the USA and the same thing could happen in the UK.

Infected pigs vomit and dehydrate due to very severe diarrhoea, leading to 100% mortality. There’s no cure and to minimise the effects the virus must be deliberately spread through controlled exposure of the herd to virus material.

For those who remember it, PEDv is similar to transmissible gastro enteritis (TGE). Having had first-hand experience of TGE in the mid 1970s, it still brings back very painful memories.

Mr Armstrong said that in the US, dead piglets are being carted off farms by the truckload. It takes six to 12 weeks for herds to recover, although in 20-30% of herds PEDv has become endemic. Infected herds have cash flow problems, plus a serious UK outbreak would lead to pigmeat shortages pulling in imports that could stick even after the industry had recovered from PEDv.

The PED virus is extremely hard to get rid of, and despite very rigorous power washing, disinfecting and flame gunning, it took one pig unit in the US 105 days to get a negative PEDv result.

“It’s vital that farmers develop good biosecurity habits and maintain strict biosecurity measures for their units,” Mr Armstrong said. “Pay attention to detail and the detail will pay for itself many times over.

“Plan for the worst and hope for the best.”

Awkward questions
Vet David Chennells delights in asking awkward questions and taking producers to task, and on this occasion it was in relation to biosecurity. Delegates were given a quiz to complete, and the answers were quite surprising.

Mr Chennells emphasised that incoming breeding stock should be kept in biosecure isolation facilities (in quarantine) for at least a month and checked daily for disease, plus the farm’s vet should talk to the source farm’s vet in relation to the health status of the source farm’s pigs.

Pig transporter wagons had always been a problem in terms of disease spread, he said.

“Insist on a clean wagon and reject it if it’s not,” he added. “It might upset your haulier, but it won’t happen again!”

Loading ramps should always be cleaned and disinfected, Mr Chennells advised, and it was imperative that drainage should always flow away from the unit.

The quiz revealed that 48% of farms still had feed delivered right into the unit, where as the ideal approach was for the bins (with long filler pipes) to be positioned close to a perimeter fence so delivery trucks stayed well outside the unit.

Failing that, if wagons had to enter the unit, then the farm should have its own filler pipe, avoiding the need to use the wagon’s pipe, which is often moved from one farm to the next, and the next . . .

All people were potential carriers of pathogens, Mr Chennells said, and making a “Danish entry system” – clean and dirty areas split by a low division, with dedicated unit boots and overalls – was well worth the cost.

Biosecurity on outdoor units, however, was very difficult and extremely worrying, he added. Given the size of the UK’s outdoor herd, it was vital that PEDv and ASF didn’t get a foothold here.

MORE INFORMATION

The Scanning Surveillance for Pig Diseases in England and Wales reports can be found at: https://www.gov.uk/government/publications/pig-disease-surveillance-reports-2014

Recent information about ASF in the Baltic countries can be found at: https://www.gov.uk/government/publications/african-swine-fever-in-pigs-in-poland-lithuania-and-latvia

Information and advice on notifiable disease in animals can be found at: https://www.gov.uk/government/collections/notifiable-diseases-in-animals

Advice on spotting the symptoms of ASF are described in a leaflet produced by a multi-national European Consortium set up to tackle the disease at: http://asforce.org/flyers/asforce-en.pdf

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