Transmission of porcine reproductive and respiratory syndrome virus by fomites (boots and coveralls)

Objectives: To determine if porcine reproductive and respiratory syndrome virus (PRRSV) can be transmitted to susceptible pigs by fomites or people exposed to infected pigs. Methods: Ninety-six 4-week-old pigs from a PRRSV-naive source were organized into six groups individually housed in isolation rooms (four replicate trials, 24 pigs per trial). Group 1 pigs were inoculated intranasally with PRRSV strain VR-2332 (2 mL, 10⁵ median tissue culture infective doses per mL.) On days 5, 6, and 7 post inoculation, investigators exposed to Group 1 pigs attempted to transmit PRRSV to sentinel pigs (Groups 2 to 5) by contact. After exposure to the infected pigs, an investigator entered the Group 2 room (Direct Contact group) wearing contaminated boots and coveralls and without washing hands. In contrast, investigators who entered the rooms housing Groups 3 to 5 were required to complete specific sanitation protocols, which included changing boots and coveralls and washing hands (Danish System, Group 3); changing boots and coveralls, showering, and 12 hours down time (Standard Protocol, Group 4); and changing boots and coveralls and showering, with no down time (Alternative Protocol, Group 5). Results: The PRRSV was detected on contaminated coveralls, boots, and hands of investigators who had contacted Group 1 pigs. Transmission of PRRSV occurred between Groups 1 and 2, but not between Group 1 and Group 3, 4, or 5. Implications: The PRRSV can be transmitted to susceptible pigs by contaminated fomites (boots and coveralls) and hands; however, the use of sanitation protocols appears to limit its spread.