Evaluation of an industry-based sanitation protocol for transport vehicles contaminated with porcine reproductive and respiratory syndrome virus

Objective: To test a protocol, using conditions found on commercial swine production units, for sanitation of 1:150 scale models of commercial transport vehicles contaminated with porcine reproductive and respiratory syndrome virus (PRRSV). Methods: Model trailers were experimentally contaminated with PRRSV MN 30-100 and either pressure-washed with cold water alone (Treatment 1) or washed and then disinfected with modified potassium monopersulfate (Treatment 2), quaternary ammonium chloride (Treatment 3), or a phenolic product (Treatment 4), each applied using a hydrofoamer. In Phase One, the presence of PRRSV RNA was evaluated by polymerase chain reaction (PCR) testing of swabs collected from the trailers' interiors immediately after washing and 30, 60, 90, and 120 minutes post treatment. In Phase Two, the presence of viable PRRSV was evaluated by swine bioassay (injection of supernatants from PCR-positive swabs) and housing pairs of sentinel pigs in treated trailers for 2 hours, beginning 90 minutes post treatment. Results: Swabs were PCR-positive 120 minutes post treatment in 18 of 20 trailers receiving Treatment 1, none of 20 trailers receiving Treatments 2 and 3, and two of 20 trailers (suspect reactions) receiving Treatment 4. Viable virus was detected both by swine bioassay and sentinel pig exposure protocols in trailers receiving Treatment 1, and by swine bioassay alone in trailers receiving Treatment 4. Implications: High-pressure washing of transport trailers, followed by 90 to 120 minutes exposure to either modified potassium monopersulfate or quaternary ammonium chloride disinfectants applied with a hydrofoamer is likely to eliminate residual infectious PRRSV.