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Transport Biosecurity - Are your vehicles transmitting disease?

by 5m Editor
12 July 2001, at 12:00am

By Jake Waddilove MA, VetMB, MRCVS - There is no place in a modern pig production unit for for dirty vehicles. They represent one of the major risks to every unit's continued biosecurity. This article takes you through the necessary steps to ensure good vehicle biosecurity enabling you to see how your farm is doing?

Jake Waddilove MA, VetMB, MRCVS
is a veterinary practitioner based in eastern England. The report has been obtained with the help of biosecurity products company DAHS. A version of this report first appeared in the Watt Pig Publication - Pig International, January and February 2001 issues.

Vehicles that can pose a
Biosecurity Risk to a Pig Farm
Pig delivery lorries
Pig collection lorries
Feed delivery lorries
Dead pig removal lorries
Staff vehicles
Engineer and service vehicles
Bedding delivery vehicles
Waste removal vehicles

One of the major biosecurity risks to a pig farm is the vehicles that service it. These range from pig delivery and collection lorries, feed wagons and vistors.

All of these vehicles pose a real threat of spreading disease. The Classical Swine Fever (Hog Cholera) outbreak of 1997-8 in the Netherlands is widely believed to have been introduced by a dirty pig lorry. In the same outbreak, which had a direct cost of US$3.2 billion and resulted in 10 million pigs being slaughtered, 24% of the spread of the disease was attributed to transport.

There are plenty of other examples of spread of disease thought to be associated with transport. Of special concern at present would be PRRS and PCV2 viruses. Bacteria can also be easily spread, and control of Salmonella will be very important for Quality Assurance. Other bacterial examples include Swine Dysentery and Actinobacillus pleuropneumonia. We even need to consider the risk of spreading parasites, coccidial oocysts and fungi.

Remembering that the greatest threat to a pig in terms of disease spread is another pig, drivers of transport visiting a farm should not be allowed to keep pigs at any other premises. The outbreak of Classical Swine Fever outbreak in the UK in 2000 turned up two cases where this has caused exceptional concern.

When considering transport biosecurity the problem of costs, both direct and indirect, will quickly arise. To clean and disinfect a large road train lorry and trailer to the highest level might cost as much as US$96 (including facility charges, operative time and chemicals). A smaller lorry done to low levels might cost US$32. Indirect costs are greater and include the costs of downtime, extra drivers etc. These are small compared with the potential cost of a major disease breakdown on a farm (e.g. US$64,000 for the initial cost of a Swine Dysentery outbreak on a 500 sow farrow to finish operation, and much more in its chronic phase) and even smaller when compared with the cost of significant disease entering a major production system. From these figures it can be seen that the cost of transport biosecurity must not lead to compromises of unit biosecurity as the costs of a disease outbreak very rapidly become much greater.

At a practical level vehicle Biosecurity poses many problems. These will vary between farms and countries, and they are summarized below:

The practical problems of Transport Biosecurity

  • Variability of construction and materials used in vehicles.
  • Vehicle design frequently does not consider cleaning.
  • Vehicle downtimes are expensive.
  • Every load must be dealt with to a high standard.
  • Adequate, biosecure facilities are needed
  • We are dealing with multiple, non-specified pathogens.
  • Weather extremes quickly compromise results.
  • Staff training must be good and ongoing ­ a problem with high staff turnover.
  • Supervision and verification are needed.
  • In many areas transport biosecurity needs to be incorporated in HACCP procedures.
  • Corrosion can be perceived as a problem ­ so follow manufacturer's instructions

What are the Important Target Areas?

  • Biosecurity prior to arrival at the farm ­ important for pig and feed lorries.
  • At arrival to the farm. Essential for all vehicles.
  • Exclusion of all vehicles from the Biosecurity Perimeter except where unavoidable.
  • Biosecurity while moving around the farm.
  • Biosecurity of all operatives involved.

What Precautions Can Be Set Up On The Farm?

Properly set up farms help reduce the biosecurity risks of transport.
  1. Any suppliers or services to the farm must be issued with clear instructions prior to coming to the farm. These should include specific biosecurity instructions.
  2. The farm should have a good perimeter. Clear instructions should be displayed for any visitors and transport approaching the unit.
  3. A member of the farm staff should be made responsible for the Biosecurity aspects of all vehicles visiting the farm.
  4. Regular inspection of all vehicles attending the unit should be made. (See below). If vehicles are unsatisfactory they must be sent away immediately.
  5. Farm staff should be trained in the important basic principles involved (e.g. farm staff should never go on the ramp of a pig lorry, lorry drivers should not be allowed to wander around the unit etc.).
  6. Feed deliveries should be to the perimeter. Feed blower hoses should be provided where possible.
  7. Pig deliveries and collections should be via a well constructed loading bay, again on the perimeter of the farm. Some farms will even have separate bays for breeding and finishing stock. Bays should be sloped to drain away from the unit, and must be easily washable. Facilities for cleaning and disinfection must be supplied and bays should be washed and disinfected between loads. Gates are needed to prevent run back of pigs into the unit and there must be clear definition between where staff and drivers can go. Clear instructions regarding the operating procedures in loading and unloading of pigs must be prepared and issued to staff and drivers.
  8. Footdips, wheeldips and/or sprays should be provided as needed. All vehicles arriving at the unit should spray or dip however clean they are. This should ideally include the wheel arches and possibly the underside of the vehicle.
  9. Drivers should be provided with boots or overboots and overalls. Footdips should be available for the driver to use at entry and during his work. The importance of these procedures increases if the driver enters the unit (e.g. if he has to deliver feed within the unit), but is of value of he does not. A practical problem here occurs if the driver has to get back into the vehicle to move it ­ he should ideally change each time, but this rarely happens.
Photo Built in protection: This lorry has an on-board spray system to wash it wheels with a sanitising solution.
Photo Disinfecting: Use a low-volume spray to deliver the disinfectant solution to the vehicle body and wheels.

Lorry Wash Facilities

Many large integrators, transport organisations, breeding companies, slaughterhouses and feed millers have established lorry wash facilities. These have special requirements:
  1. They must be biosecure ­ you don't want rogue drivers washing here introducing new pathogens. Cross-contamination between lorries must be avoided. This occurs where two lorries are washed in close proximity and contamination is sprayed from one to the other or if drivers walk contamination back into the vehicle as they clean it.
  2. There should be adequate water supply. If this does not include hot water the cleaning equipment must be capable of heating it. Flow rates and reserves must be appropriate.
  3. The wash area and a stand off area must be sloped to allow for drainage and truck drainage.
  4. If appropriate heating of the area will be needed. Adequate lighting is essential. Drainage must be efficient.
  5. Metering for disinfectants is needed, or ready-made stable dilutions must be supplied. Bedding disposal is needed if appropriate.
  6. The facilities must be regularly cleaned and disinfected.
  7. Monitoring systems are strongly recommended.
  8. If special facilities are not provided the chances of a good lorry Biosecurity programme are considerably reduced. One of the most worrying aspects is where a driver returns to a farm to wash down his vehicle. Farms that need to wash and disinfect their own vehicles should make arrangements to do so well away from the farm, at a non-stock enterprise.
Photo Remove any deposits of mud, straw and dirt etc. Scrape and brush the sidewalls, division gates, floors and tail lift of the trailer.

Photo Soak the vehicle to loosen dirt. Wash all of the vehicle, equipment, tools and the belly box. Start at the top and work down each side paying particular attention to the wheels, wheel arches & mudguards.

Photo Disinfect all vehicle surfaces inside and out using a suitable, approved disinfectant such as UK MAFF approved DAHS Virkon S at a dilution rate of 1:100. NOTE use of disinfected protective waterproof clothing.

Photo Disinfect the cab. Remove items such as mats and boots etc. and vacuum up all loose debris and dirt. Wash/soak the floor, mats and pedals allowing 10 minutes for it to penetrate and loosen dirt. Using a clean cloth soaked in suitable disinfectant (virkon S) wipe over the floor, mats and foot pedals.

Pig Transport Procedures

Biosecurity procedures for transport used to move pigs are the most demanding. They will be dealt with first and then we can extrapolate to other transport.

1. Initial Dry Cleaning:
This stage involves the removal of all gross organic soiling (that is dung, bedding and other waste). This is essential because of the high levels of pathogen challenge and soiling which may reduce the later efficiency of cleaning and disinfection. All dung, soiled bedding and unused food must be removed, as must other gross contamination. Operatives can use brushes, scrapers and shovels. They should first concentrate on the interior of the lorry working from the top deck downwards paying special attention to difficult areas such as gates and sidewalls. Next concentrate on the outside of the vehicle working from top to bottom. Do not forget ramps, boarding platforms, bodywork and wheels and wheel arches and boxes.

2. Cleaning and Sanitising:
Following this initial cleaning high levels of infective material remain. Cleaning is required to remove these. The target levels of bacterial reduction are shown in the adjacent table. As this table shows, cleaning is facilitated by the use of a heavy-duty detergent (e g. Biosolve ­ - by spraying at 1:100 or foaming at 1:50). The use of this product will ensure a good clean and reduce the time taken by up to 60%. It is important that the detergent should be comparable with later disinfectants. Again, work from top to bottom and outside to inside paying special care to all difficult areas that might harbour dirt or faeces.

At this stage all organic matter must have been removed.

3. Disinfection Stage:
Once the vehicle is completely clean there will be a residual level of pathogenic organisms left, as is shown in table 3. The purpose of disinfection is to kill these and achieve adequate final levels of pathogen kill.

A broad spectrum, proven activity disinfectant should be used. In view of problems in the modern pig industry with viral diseases (e.g. PRRS, PCV2 and CSF) it is strongly advised to use an agent with specific activity against these aswell as other pathogenic organisms ­ (e.g. Virkon S - this can be applied with a backpack sprayer or low volume spray at levels of 1:100). Take care to ensure all areas are thoroughly disinfected starting outside the vehicle and working inwards. Remember that all removable equipment must be cleaned and disinfected in the same way, and you must do areas such as wheels, wheel arches and boxes. Finally, remove the lorry to allow run off and drying.

4. The Driver's Cab:
The cab presents a problem. All removable items including the floor mats, clothing, boots etc. must be taken out of the cab and thoroughly cleaned. Next use a brush to remove any debris from the cab. Pay special attention to the foot pedals.

Using a soft brush and a heavy-duty detergent (Biosolve) clean the cab floor pedals and other dirty areas. Allow at least 10 minutes for the detergent to penetrate and loosen dirt before rinsing. Then use a soft brush or cloth to apply disinfectant (Virkon S) to all possible areas.

All items that have been removed from the cab should be cleaned and disinfected in a similar way.

Other Vehicles

Similar principles will be employed. The levels of organic material are lower on feed lorries etc., but special care is needed on the feed delivery hose and its housing.

A special risk is the dead pig collection lorry. This is a high level risk, especially if it has been to other farms and may even contain deadstock from them. It must be kept as far away from the unit as possible. Once it has collected spray disinfect the area where it stood.

Waste removal vehicles (e.g. slurry tankers or muck spreaders) should not be shared between farms. If they are shared there must be a full and thorough clean up both internally and externally. Faecal material running back from slurry tankers is a particular risk. Disinfection must be only done once the vehicle is thoroughly cleaned. A downtime of 48 hours is advisable before moving to the next farm.

Staff vehicles should be left on the perimeter of the farm and should not be used to visit other farms. Ideally they should pass through a wheel dip or spray at arrival.

The Steps to reducing Pathogen Levels
Level of Cleaning
Viable Bacteria/sq.cm.
Prior to cleaning
50,000,000
After plain washing
20,000,000
After hot wash and detergent
100,000
Engineer and service vehicles should be treated in the same way. Special precautions are needed if they enter the farm, when an undertaking of pig freedom should be combined with thorough cleaning and disinfection. An area of concern here is any equipment that the occupants bring in with them. (In one well-known case in the UK Swine Dysentery was introduced into a farm via a dirty engineer's toolbox). All such equipment must have an undertaking of pig freedom, and be thoroughly cleaned and disinfected prior to entry onto the farm. It must be inspected as such.

Bulk containers will be cleaned and disinfected as other vehicles. The inside can be fogged (using Virkon S).

Scheduling of Transport

This is a critical part of biosecurity. Within the genetic breeding companies there is strict scheduling such that lorries only move down individual pyramids. Similar approaches should be taken in multiple site production, with breeding herds given the highest preference. A particular risk is lorries making multiple loads between 2 farms and good biosecurity principles must be maintained here. This becomes even more important with lorries moving between farms and slaughterhouses.

It is preferable to separate lorries to be used for breeding herd movements and slaughter pig movements. Precautions for continuous production and single site enterprises are just as important, but often more difficult to achieve because of the lack of dedicated transport.

What is the ideal downtime after cleaning and disinfection of pig lorries? Economic and Risk consideration must be taken, but sample figures for high health farms are 12-24 hours. Commercial units frequently do not achieve this.

Similar precautions can be used for other transport, especially that which moves between units, such as feed lorries. Here the movement down pyramids and dedicated transport are the main tools.

Monitoring and Verification of Cleaning and Disinfection

This area is highly important, and can prove a real challenge. If HACCP is used in a pig production system it is essential, but even if HACCP is not followed it is still needed to ensure that the programme is followed correctly. As previously stated there should be one person at each farm responsible for this. Within companies there will be specialist personnel who have the maintenance of the vehicle Biosecurity programme and its monitoring and verification as at least part of their job.

There are 3 main methods of checking how well the vehicle cleaning and disinfection has been done:

Visual inspection:
Will give a good idea of the quality of gross cleaning, but no more. At a farm level this is much the most important method of checking, especially as it can be done on every load. This is the area where the responsible member of farm staff should be heavily involved. Inspection of the vehicle should be done outside the unit, preferably on an area of hard standing. Start by looking at the wheels, wheel arches and mudguards. If possible look under the vehicle, and always check boxes and the cab.

Inside the vehicle inspect closely for any faeces or other waste material that have not been removed. Look under support beams, under gates and in crevices and corners. The ramp and loading platform require special attention. On food lorries inspect the delivery hose and any pallets used. Check any equipment that the vehicle is carrying into the unit.

Ideally the vehicle should carry a Biosecurity log, which will show the last load carried, when it was carried and what Biosecurity precautions have been taken since that load. This log should be inspected. In a similar way it is a good idea to keep a log of the vehicles visiting a unit and their checking. Remember that the operative inspecting the vehicle must take appropriate precautions before re-entering the unit.

Using swabs and bacterial culturing
Special systems have been set up (e.g. The RODAC System) whereby the area to be tested is swabbed and these swabs are cultured and evaluated qualitatively. The major disadvantage of this is the time needed (48 hours) which makes this a tool for checking operative performance rather than the individual lorry. The system only checks for bacteria (and those which grow on the plates within the 48 hour time), but it can be used as a measure of overall cleaning and disinfection.

Using a system to detect Adenosine Triphosphate (ATP)
This is a compound present in organic debris, faeces, bacteria, fungi, protozoa, parasites but not viruses. An example is the Lighting System (IDEXX). This is a very sensitive test and interpretation of results requires some care. It produces rapid results, but initial set up costs are high. Depending on the sensitivity settings used it is more of a measure of cleaning efficiency rather than disinfectant success. One area of concern is verification that the correct levels of disinfectant have been used. Obviously good standard operating procedures will help this, but to date only sophisticated slow chemical analysis has been available. DAHS is developing a paper dipstick approach, which will give rapid results when used on a solution. There is no current economical method of checking a vehicle for disinfection once it is dry.

Correct recording of cleaning and disinfection combined with validation records will be an important part of assurance of truck biosecurity. Individual vehicle Biosecurity logs must be made and kept, as should records of facility inspection and chemical usage. This will be an important part of HACCP procedures.

In Summary

Transport biosecurity is essential to prevent the spread of disease between units. Poor vehicle design, variable construction materials and economic considerations are the biggest obstacles to this. It is necessary to have good facilities and to set up a comprehensive programme that is frequently monitored and verified. This programme should include high quality proven products (e.g. Biosolve, Farm Fluid S and Virkon S ­- DAHS). Operative training is another important area to address.

The cost of transport biosecurity is often quoted as a problem, but remember that failure can be catastrophic to the health and profitability of pig enterprises and sometimes entire pig industries. As a result transport biosecurity must be an important part of disease control regulations and HACCP procedures.