In an online seminar, ‘Defend against disease: don't break the chain’, organised by BPEX this week, pig vets from Garth Partnership in Yorkshire reviewed the current risk of swine dysentery, opening a discussion on how each part of the supply chain can strengthen its defence against this damaging disease. Helen Clarke of BPEX then described how the 'lorry wash' initiative can contribute.

The event was set up following an increase in outbreaks of swine dysentery in North Yorkshire over recent months because producers need to be aware of the situation, which has impacts for the whole industry. More than 40 producers participated in the evening seminar.

What is Swine Dysentery?

Typically, swine dysentery affects growing-finishing pigs in the age range of 10 to 20 weeks, according to Henrieke Jaeger of the Garth Partnership, a pig veterinary group based in Yorkshire, the region affected by the current spike in outbreaks. In fact, pigs of all ages can become infected, with gilts entering the breeding herd also a risk group. She explained that the main symptom is scouring (diarrhoea), usually with blood or mucus. However, some pigs might show less severe symptoms – similar to mild colitis. The incubation period – from infection to showing symptoms – is typically around five to 10 days.

The cause is a bacterial spirochaete, Brachyspira hyodysenteriae. Its virulence varies with the strain, as do its abilities to mutate and recombine, characteristics that impact the development of drug resistance.

Pigs pick up the infection from faeces in their environment and once ingested, the bacteria colonise the large intestine, where they multiply and cause inflammation of the intestine, which leads to diarrhoea and the infection of other pigs.

Ms Jaeger stressed that viable bacteria may still be excreted without obvious symptoms – for up to 90 days after apparent recovery.

Control of Brachyspira

Survival times for Brachyspira depend on the conditions: under cool conditions and in the presence of pig faeces, they have been found after 112 days. They like cold and wet conditions and the presence of faecal material, typical of UK pig farms oat this time of year, she said.

The bacteria can be killed by thorough cleaning and disinfection, said Ms Jaeger, stressing the need to remove all organic material, to dry surfaces properly and to use disinfectants at the correct concentration.

Antibiotics are also effective to treat pigs but their use risks the development of antibiotic resistance in the pathogen.

A study in 2007 reports that swine dysentery cost around £10 per pig, and it is likely to be considerably more now, said Ms Jaeger. The costs arise from the pig's poor health and performance as well as medications.

How Swine Dysentery Enters the Pig Unit

There are many ways for the infection to gain entry to the farm, said Ms Jaeger, citing pigs, vehicles, other animals and people & fomites. Replacement gilts, boars and weaners from infected farms present a clear risk, and the risk increases with the number of sources, she said. The infection can also enter on vehicles of all sorts – livestock and deadstock lorries, feed trucks, post and semen deliveries, services such as electricians and on private cars and motorbikes. Other animal sources include rodents and pests, wild birds and dogs. Finally, staff, drivers, visitors, family and all types of equipment can also bring the infection onto the farm.

In a survey of the swine dysentery outbreaks in East Anglia between 2006 and 2009, Jake Waddilove found that the majority of infections could be traced back to pigs entering the farm but vehicles and management (people) were also important source of the bacteria.

What Action to Take if Swine Dysentery is Suspected

Blood and/or mucus in the faeces is the key symptom, even if few pigs are affected at the time. The vet should be contacted immediately, so that tests can be carried out to confirm (or rule out) swine dysentery, said Ms Jaeger.

For the pig producers affected, contacting the vet should be the first step, in order to obtain a diagnosis and discuss medication. In the short term, it is vital to minimise the spread of infection, both within the farm and to other units. On the farm, that means limiting the movement of muck, pigs, vehicles, staff and equipment between the houses, and Ms Jaeger stressed the need to clean boots properly when moving from one house to the next. To reduce the spread off the farm, commmunication is key, she added.

In the longer term, eradication is the key to success and it can be achieved, she said, citing the experience of the region of East Anglia.

Summing up, Ms Jaeger recommended: "To control swine dysentery, get your biosecurity up to speed."

To keep the disease out of the farm, she suggested closing the herd and buying from just one reliable source which is swine dysentery-negative. Communication with the supplier and between the respective vets is also important, as is complete isolation of new breeding stock for at least three weeks.

The best way to stop the spread of swine dysentery on vehicles is to keep them off the farm – even staff cars – and keeping the perimeter secure.

Ms Jaeger said that good communication with hauliers can be important on health issues to allow work schedules to be adjusted to fit the health status of the farm and so that the importance of vehicle cleaning is understood. Ideally, there should be a covered loading area with a clear line dividing the areas accessed by farm staff and by the driver so that there is no crossover.

To prevent feed vehicles bringing in infections, bins and bagged feed stores should be on the perimeter of the farm. If that is impossible, cross-over of vehicles should be avoided and there should be a wheel-wash, the farm's own blower pipes should be used and both driver and vehicle should be inspected before they are allowed to enter. Similar conditions should apply to deadstock lorries, bedding deliveries and luck and slurry collections.

Open communication with the abattoir is vital, said Ms Jaeger, so that work can be re-scheduled so that infected premises can be visited last and particular attention is paid to the cleaning and disinfection of vehicles.

To control the spread via other animals, she suggests cleaning up spilt feed promptly and covering hoppers, bins and barrows to discourage vermin, and also to maintain buildings in good condition and bird-proofing them with netting. Baiting the perimeter will also help, and all other animals should be kept off the farm.

Staff should have no contact with other pigs or the slaughterhouse and clothing and boots should be completely separate in order to stop spreading the disease on people and fomites. Visitors should be restricted to essential ones only and must use a foot dip, while shoes/clothing should be changed on entering and leaving the farm.

Current Disease Status in Yorkshire

There have been reports of recent outbreaks of swine dysentery in North Yorkshire, with six farms with confirmed cases.

Some time ago, BPEX set up a swine dysentery producer charter, which provides full details of outbreaks on other signed-up units in a producer's area as soon as the confirmed reports are received. Updates are sent via email, letter and text message. To sign up for Yorkshire and Humberside Health (YHH), click here.

Since the latest outbreaks, more than two dozen new members have joined the swine dysentery charter following the recent cases in North Yorkshire, according to Helen Clarke of BPEX.

Summary

Swine dysentery is a bacterial disease of pigs, particularly in the growing-finishing phases. Pigs show signs of blood and/or mucus in the faeces. The disease can be spread easily by pigs entering the farm, as well as on vehicles, people and wild animals.

A high level of biosecurity is the best way to keep the infection off the farm as medication risks the development of antimicrobial resistance.

Good communication throughout the supply chain is vital – between producers and their neighbours, veterinarians, abattoirs and suppliers.

Once the disease strikes, eradication is the best policy and can be achieved.

Further Reading

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Go to our previous news item on this story by clicking here.

Further Reading

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Find out more information on swine dysentery by clicking here.