Transportation Cleaning and Disinfection
Proper cleaning and disinfection of transportation equipment is one of the key methods to prevent disease introduction into a swine farm. Management needs to emphasize the importance of this area to the biosecurity of the operation. Staying focused on transportation cleaning and disinfection can be challenging. It is important to continually monitor the cleaning and disinfection process.
Numerous references document the ability of viruses and bacteria to survive in the environment. (Beran, 1991; Benfield et. al., 1999; Taylor, 1999; Saif, 1999; Schwartz, 1999; Harris, 1999) PRRS and TGE viruses are both able to survive for long periods at low temperatures. Salmonella is very hardy and able to multiply at 7-45°C. PRV reached 99.9% inactivation within 40 minutes under ultraviolet light in a thin liquid suspension. PRV could not be recovered on dried glass or gelatin. This points out the need for allowing time for drying of the equipment following cleaning and disinfection. Exposure to sunlight may also help eliminate pathogens.
Disinfectants and Detergents Most of the common disinfectants are effective with the proper cleaning, environmental temperature, and disinfectant contact times. Inactivation of the microorganisms is a function of exposure time, type of organism, concentration of organism on the surface (contamination level), concentration of disinfectant, temperature, and pH. Empirical rules suggest inactivation time decreases by a factor of 2 to 3 for each 10°C rise in temperature, which makes it important to use hot water. Because of the differences in disinfectants available, it is important to evaluate their effectiveness in the specific environmenti—trailer type, ambient temperature, possible safety issues, and interactions with other compounds used.
Cleaning compounds like soap or detergents are surface-active chemicals that can modify the solubility of water. Cleaning compounds should have the following properties: wetting or penetrating, rinsing properties to lower the surface tension of the water, emulsifying properties (degreasing) to break up fats and oils into smaller particles, foaming to increase the contact time, sequestering to remove or inactivate water hardness, and water conditioning to soften the water by sequestering mineral ions. Alkyl detergents meet most of these requirements (Jeon, 1998). Use of a soap or detergent is an important first step in the cleaning process. An example of the benefits of this is demonstrated in Table 1.
Table 1. Effects of Various Washing Steps. Gadd, 1999
|State of house||Viable bacteria/sq. cm.|
|Immediately after pigs out||50,000,000|
|After plain washing||20,000,000|
|Hot water wash and detergent||100,000|
|Target before disinfection||1,000|
Summary of Properties of Disinfectants
- Halogens (chlorine and iodine), phenolics, and quaternary ammonium compounds (QAC) are effective against Gram positive and negative bacteria, Mycoplasmas, and common viruses.
- Chlorine is inactivated by organic material, ammonia (urine), and has some user safety issues.
- Iodine compounds are more effective in organic material and have a good spectrum of activity but can stain equipment.
- Phenolic disinfectants have a broad spectrum of activity, are tolerant of organic material and hard water, have residual activity, and are biodegradable. Anionic detergents work better with phenols.
- QACs have similar activity as the phenols but are cationic surface agents which act as surfactants. They form a bacteriostatic film and are effective on aluminum.
For any disinfectant thorough rinsing after the cleaning step is necessary to prevent any adverse reaction with the detergent.
Table 2. The Antimicrobal Spectrum of Disinfectants, Classified According to Their Chemical Composition. Quinn, 1991. ++highly effective; +effective; +/-limited activity; -no activity; a individual members may vary from the activity listed for that category; bvaries with the composition of disinfectant.
|Microorganisms Listed In Order of Increasing Resistance to disinfectants||Chemical Disinfectantsa|
|Enveloped viruses (TGE, PRRSV, PRV)||++||+||+/-||+/-b|
Providing an enclosed, well lit, and heated building for shelter will greatly improve the quality of the washing. Federal regulations require that all the wastewater be captured in an approved holding facility. If bedding is used, it must be held until it can be disposed of properly or applied to agriculture land. Proper slope for washing out the trailer is necessary. A minimum of 2-3% slope to get the wash water to run out is recommended. A pressure washer with high pressure and hot water is needed. Recommendations are to use a minimum of 2,000psi with 4 gallons per minute of water. An accurate metering device is important in the application of the soap and disinfectant.
- Bedding and large debris should be scraped out of the trailer before entering the wash area. If no bedding is used, soaking the trailer before washing will reduce wash time.
- Use of soap is highly recommended to reduce washing time by loosening debris. Normally it is applied on low pressure. Apply soap and water to the outside of the trailer first. Next move inside to the front of the top deck and start the soap application at the junction of the floor and side. Work up the sides from bottom to top to reduce streaking and give more surface contact time. Soak the roof and floor while working to the back of the trailer. Soaking the whole trailer will give plenty of time to loosen debris. However, don’t allow the soap to dry or it will be harder to rinse.
- After soap has been applied to the whole trailer move back outside and start rinsing and cleaning the trailer from the top down. After rinsing the trailer, soap and wash the cab to give additional soaking time inside the trailer.
- Rinse and clean each deck from front to back and ceiling down starting with the top deck. Pay special attention when washing to spray the flooring support members on the ceiling of the bottom deck in a multi-deck trailer, behind all the gates, in all the corners, and the inside of the roll-up door. Unloading ramps should also be washed. During the winter it is essential to wash all the winter panels as well as the storage box after every trip. Any time of the year wash and disinfect the cutting boards, paddles, boots, and coveralls after every load.
- After the trailer has been rinsed inside and out, apply the disinfectant at the appropriate dilution rate. Start on the inside of the trailer and finish on the outside. Disinfectant should be applied at low pressure because many of the metering devices will not dilute properly on high pressure.
- Clean out the inside of the cab, wash, and disinfect the floor mats.
- After disinfection, park the truck on a slope so all the remaining water can drain out. During the winter leave the truck in the washout bay, or park it in a protected area to ensure no pooled frozen water.
Monitoring the quality of the cleaning and disinfection is possible through the use of environmental culture media or ATP tests.
Beran, 1991. Transmission of Aujeszky’s Disease Virus Pages 93-112 in Eradication of Pseudorabies Virus. First International Symposium on the Eradication of Pseudorabies.
Benfield et. al.,1999 Porcine Reproductive and Respiratory Syndrome, Disease of Swine, 8th Edition. Iowa State University Press. Ames, Iowa. Page 203.
Taylor, 1999 Actinobacillus pleuropneumonia, Disease of Swine, 8th Edition. Iowa State University Press. Ames, Iowa. Page 345.
Saif, 1999 Transmissible Gastroenteritis and Porcine Respiratory Coronavirus Disease of Swine, 8th Edition. Iowa State University Press. Ames, Iowa. Page 296.
Schwartz, Salmonellosis, Disease of Swine, 8th Edition. Iowa State University Press. Ames, Iowa. Page 535.
Harris, Swine Dysentery, Disease of Swine, 8th Edition. Iowa State University Press. Ames, Iowa. Page 583.
Jeon, 1998 Cleaning Compounds and Procedures Page 103 in Manual for Quality Assurance of Food Products 4th Edition Kansas State University.
Quinn, 1991 Disinfection and Disease Prevention in Veterinary Medicine Page 846-868 in Disinfection, Sterilization, and Preservation 4th Edition.
Gadd, 1999 Tidy Tidbits for Cleaning Up Your Hog Operation Page 28 in National Hog Farmer July 15, 1999.
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