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A new look at biosecurity

By Dr Jim Robinson, a veterinary consultant
Dr Robinson discusses how disease can be spread on the farm and what biosecurity measures pig producers can take to protect their herds.
The word biosecurity evokes groans and yawns whenever the subject is raised, more especially but not exclusively amongst those who have not had the experience of taking thousands of healthy pigs, some only a few days old, to be shot with a captive bolt, their throats cut and their bloody carcasses piled on to bakkies for disposal in long, deep trenches.
In the year 2000 there was a memorable outbreak of foot and mouth disease in Kwazulu-Natal, memorable for two reasons
Firstly, it was a new type for South Africa — an exotic virus by definition, and secondly, it brought sharply into focus the necessity for a biosecurity system that was going to protect the national pig herd from unexpected and destructive diseases.The biosecurity structures needed to be integrated on a national, regional and individual farm level, with clearly understood standard operating procedures (SOPs) and a rapid response capability when required.
The unpredictability of new diseases appearing in this country, — one of the down-sides of the by then well established global village phenomenon — was illustrated when we diagnosed porcine respiratory and reproductive syndrome (PRRS, “blue ear”) in the Western Cape in 2004 and again (a new infection by a separate strain of the same virus) in 2007.
It is a tribute to the combined efforts of the national and the Western Cape Veterinary Services and members of the Pig Veterinary Society and SAPPO, together with the Western Cape Minister of Agriculture and the Provincial Disaster Committee, the army and the police, that both outbreaks were successfully eliminated — an achievement that is rare for this disease.
In 2005 an outbreak of classical swine fever (CSF), also known as hog cholera, was diagnosed in the Eastern Cape, and this led to a protracted and extremely expensive culling campaign involving a similar cooperative effort by all concerned.
The outcome of this campaign seems to have been successful — some reservation remains because of the remaining pockets of feral pigs that may still exist and may still carry the virus.
The stamping out policy that was followed in all these outbreaks was the accepted radical control method of the time.  It was both successful and also very expensive inasmuch as the operations themselves were costly, and so was the compensation paid to owners who suffered losses as a result of these “controlled diseases” — so defined in the Animal Health Act.
The total bill has amounted to hundreds of millions of rands and government has decided that, from now, no further compensation will be paid for these or similar diseases. This despite the convincing arguments that failure to contain and eliminate exotic destructive diseases would, and may yet, be very much more expensive to the national agricultural economy than paying compensation in a culling operation.
The government does not have to take advice and act as recommended and the strong likelihood is that in any future controlled disease outbreak the pig industry is on its own.
Whatever needs to be done to control the outbreaks will be done by the government but compensation is not contemplated.
Producers’ responsibilities
The word biosecurity evokes groans and yawns whenever the subject is raised, more especially but not exclusively amongst those who have not had the experience of taking thousands of healthy pigs, some only a few days old, to be shot with a captive bolt, their throats cut and their bloody carcasses piled on to bakkies for disposal in long, deep trenches.

  • That this situation will arise again is not to be doubted; it is a matter of when, not if.
  • It is also wishful thinking that living and farming inland, far from harbours and airports, is any guarantee against exotic infections.
  • Pigs and meat are carried long distances within South Africa to find better markets and we have long, poorly patrolled borders with six neighbouring countries.
  • The thousands of small-herd and poor-resource farmers whom SAPPO and others are educating and uplifting often cannot afford the more effective levels of biosecurity, but are increasingly entering the conventional markets.

The hard truth is that the major responsibility and expense for protecting the country’s herds rests with the owners who can expect no subsidies for money spent and no compensation for pigs culled and money lost in the event of a catastrophic disease outbreak.
In most cases the perceived reason for a sound self-protection system is not the fear of something exotic and destructive but rather to protect one’s own herd which may be at a high level of production due to its high health status.
There is a real danger of pig pathogens that are common in many herds coming into high health herds.  Such diseases can have serious economic consequences if introduced to the relatively un-challenged and therefore immunologically un-prepared super herd.
Reminder
The following is intended to re-look some aspects of biosecurity in a slightly different way; as Do’s and Don’ts and some challenges to the conventional wisdom concerning what works and what doesn’t.
• We are usually and correctly told that the most likely source of new pig diseases is pigs, followed by people, clothes, feed, vehicles, pests, dogs, wind, rain, birds and dust, in a sort of descending order of controllability.
• Those of us who are not microbiologists often labour under the illusion that disinfectants have instant and almost magical powers to kill anything that we don’t like and can’t see;
• We tend to concentrate on the visible and doable aspects (fences, gates, locks and notices) and there is nothing wrong with that, but it is not the whole story;
• We also need to look at those things we cannot easily control but which may be important to our herd health; some are dealt with below:

Dust, wind, rain

These natural forces, all of which can carry viruses, bacteria, spores and fungi for kilometres, cannot be kept out of ordinary piggeries that do not have closed rooms and forced ventilation.
Don’t:
allow every pig movement to become a dusty, noisy stressful rodeo.
Do:
control nature on your own piggery if you can:

  • Construct brick/cement pathways with sides between buildings for pig movement;
  • Plant grass over as much of the piggery area as possible;
  • Make sure that drainage routes go to the intended area (ponds, separator) without running from dirty through clean areas.

Birds
Why are they there? Usually because there is an invitation. What do they bring?

  • Avian tuberculosis, erysipelas, hungry mouths — some birds eat their weight in grain every day
  • Don’t:  Waste feed by leaving it exposed, lying around, on the ground under storage silos or faulty delivery conveyors,
  • Pile up compost material close to pig houses,
  • Leave bedding outside or not properly roofed to keep dry.

Do:

  • Tidy up the house keeping
  • See to the repairs and maintenance of the feeding and storage system,
  • Bird-proof pig houses if this will not interfere with ventilation.

Pests
Rats, dogs, flies have no place in a piggery; they are indicators of the level of construction and cleanliness of the system and hence the prevailing level of stockmanship and biosecurity.
Don’t:

  • Poison the birds that are on our side by using rat poisons that will kill owls eating sick rodents,
  • Rely on cats to control rats; they can become the pest and start on piglets when the rats are scarce,
  • Invite flies by offering them wet, dung-rich messes to lay eggs and feed maggots,
  • Think that a fence is dog-  or pig- or thief-proof unless it is constructed to fill the hollows and stony places and cannot be dug under or easily climbed over.

Do:

  • • Spend money where it is going to be effective: a fence is as good as its weakest, lowest, darkest spot,
  • Use the specialist pest control services that are available,
  • Clear the area around the fence, and plan the road for deliveries and loading to match the fence.

Vehicles
Feed trucks, loaders for slaughter pigs, couriers bringing medicines, company reps, officials, vets and advisers all have reason to come on to the farm and all can bring contamination if they visit several properties on the way. There are ways of ensuring that they do not pose a threat.
Don’t:
waste time and money on ineffective measures such as tyre dips and sprays; most vehicles arriving at piggeries have travelled some distance over roads that are hot or wet or dusty and used by other cars and lorries. This, added to the strong centrifugal force on a rotating tyre will usually have a better cleaning effect than anything that happens on the farm.
The worst they can bring is probably firmly stuck to the inside of the bumpers. The bit of wet that can be added at the farm entrance is more likely to dislodge contaminated dust or mud than make it safe.

  • Buy feed from sources that are not conscientious about cleaning.
  • Feed trucks come from millers who know very well, or should, that the consequences of sending feed out in dirty trucks will be catastrophic for farms and their businesses.  They also have, and use, effective cleaning equipment for every consignment.
  • Make it easy for slaughter pig collectors to come on to the farm unless you know that the vehicle has been properly cleaned and not visited any farm before yours since.  Abattoirs have good cleaning systems as a rule.

Do:

  • Spend the available money on making a road alongside the fence on the outside and placing the feed silos or storage tanks adjacent to the fence on the inside, so that the feed can be augured over the fence without the truck entering the piggery at all;
  • Place your loading ramp against the fence so that pigs are loaded on to vehicles that likewise do not come into the piggery;
  • Place your office outside the piggery so that all drivers — who are more dangerous from a contaminant point of view than their vehicles — are kept out of the pig area.

Change rooms showers and foot baths
There are a lot of misconceptions leading to acts of misguided faith concerning the cleaning of people entering the larger, well organised piggery.  There are the labourers who work there all day, the artisan who goes in and out fixing and building things, the manager who has to go in and out to supervise and monitor, the owner who pays visits and various less frequent visiting contributors to the success of the enterprise and also to the risks of bringing in disease.
Because people are daily or frequently in the piggery, they are much more important as threats to the resident stock than are pigs, which are infrequent additions, usually planned and prepared for, and hopefully from a known safe source.
Exceptions here are the small herd piggeries sourcing and selling pigs locally for the most part, but sometimes (and this is where the vital necessity for understanding through education comes in) from passing speculators or uninspected herds.
Don’t:

  • Imagine that by adopting a policy of “shower in, shower out” that you have solved any problems; the facilities have to be bright, clean, private, comfortable, be supplied with plenty of warm water and antiseptic soap  and spacious enough to be inviting.  They must also be unavoidable and not depend on the conscientiousness of the entrant. There are too many piggeries where the shower exists, out of the way, next to the toilet, in the office area, with no change room facilities either side of it, and being used to store the disinfectant and other items too big for a shelf.
  • Think that unless you have the full monty of dirty and clean change rooms, compulsory shower and shampoo, clean/disposable piggery outer clothing and boots, you cannot go into a piggery without being a threat. A good second best is a change room where street clothes are hung up, preferably in a closed basket or clean locker, and replaced with clean or disposable outer garments that never leave the piggery except to be laundered (unless there is a laundry on site, next to the canteen).  This type of facility is less “pt” to abide by and consequently more likely to be followed without reluctance and compulsion. After all, hospital operating theatre staff don’t usually shower before operating; they scrub hands and arms and put on sterile gowns and head coverings and that seems to do.
  • Regard the labour force as different from anyone else going into the piggery; they are in close contact with all the pigs all day, getting themselves and their clothes dirty and usually happy to shower, especially on the way home.
  • Put too much faith in foot baths; they are a great power for good if it is realised that disinfectants have limited powers:

They will kill what they are registered to kill but not instantaneously —only flame throwers and concentrated sulphuric acid will do that.
They are handicapped by the presence of any organic material, from pig dung to mud to spilt feed.  Cleaning is 90% of disinfection — it is when the boots (or any surface for that matter) look as if they don’t need disinfecting that the disinfectant is able to do its work.
Pigs
So much is written about pig purchases and treatment and some wishful thinking about quarantining pigs joining a herd that there are only two points to make here:
Don’t:
think that you have a quarantine arrangement on your farm unless the pens are at least 400 metres up-wind from the main piggery and the labourer who looks after the new pigs goes through the same cleaning regime every time he goes there and returns to the main piggery (it is unlikely that a dedicated worker will be used for the quarantine pens).

Do:

place more faith in the source of the pigs than in half-serious quarantine arrangements on your own farm; if quarantine is necessary or even desirable, let it be on the supplier’s property with a supervised regimen of vaccination and treatment.
Please take biosecurity seriously, wherever you are — there is too much at stake to be casual.

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