Repair and maintenance workers can unintentionally bring PRRS virus onto farms. How can we prevent this when some of their equipment is hard to wash and disinfect?
Farm maintenance is one of the ways a new PRRS virus strain can be introduced on a farm. Obviously, without maintenance there would not be this specific risk, but everyone knows that farms need maintenance.
After reviewing some outbreaks due to this reason, we realized that the key is the proper management of the tools used. Very often maintenance teams working in farms are specialized in this type of facilities, and therefore they are moving between farms often, sometimes even in a matter of minutes or hours. PRRS virus is not very resistant in the environment, but it is resistant enough to infect a farm if the infected material is introduced and there is direct contact with pigs.
The material to be used can be disinfected in the disinfection and drying room (D&D room). A specific room should be used as a D&D room for fomites. All incoming supplies should be placed in this room, disinfected on all sides, and allowed the minimum 2 hour contact time prior to entry. This can be done using a cold fog mister to create a “fog” of disinfectant. After 5 minutes minimum contact time, the fomites should be rotated, “fogged” on their underside for a minimum of 5 minutes, and then allowed to remain in the room for a minimum of 2 hours.
Quaternary ammonium + glutaraldehyde mixtures (Synergize) and modified potassium monopersulfate (Virkon) disinfectants diluted to 0.8% and 1% respectively are recommended for use in this situation. But sometimes this will not be enough, or it won’t be practical if the equipment cannot be exposed to disinfectant. In such a situation the best would be to leave the material in quarantine. At room temperature and in a dry environment, the virus persistence would be no more than 3 days, but just raising the room temperature to 37oC the virus will be inactivated in 24 h.
It is a good idea to have most of the tools necessary for regular maintenance work on the farm, thus avoiding the need to have to brought into the farm.
If you want to know more about diagnostic and monitoring read out chapter: Biosecurity.
Marcovetgrup S.L. – Spain