#09-152

Complete

Date Full Report Received

06/16/2010

Date Abstract Report Received

06/16/2010

Investigation

Institution:
Primary Investigator:

Porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (M hyo) are economically significant pathogens of the respiratory tract of the pig. While elimination of these pathogens from individual farms is possible, re-infection via the airborne route is a frequent and frustrating event. Therefore, the objectives of this project were to 1): evaluate the efficacy of mechanical filtration (MERV 16, MERV 14) and antimicrobial filtration and 2): To improve the level of understanding of the meteorological risk factors associated with the airborne spread.  The study was conducted using a model of a swine-dense production region. The model contained population of pigs experimentally inoculated with PRRSV and M hyo which served as a source of pathogen-positive bioaerosols for the “region”. In addition, the model contained 3 other facilities, representing neighboring farms which were located 120 m away (downwind) from the source herd. Two of these facilities contained air filtration systems while the final facility served as a non-filtered control. In addition, on-site meteorological data were collected to determine the conditions associated with the airborne spread of either agent. Over a 2-year period, a variety of samples were collected to determine whether the various air filtration systems (MERV 16, MERV 14 and antimicrobial filters) could prevent airborne spread of PRRSV and M hyo. Over the course of the study, pigs housed in any one of the filtered building remained free of both PRRSV and M hyo infection. In contrast, airborne transmission of both agents was observed in the non-filtered facility on a regular basis. Meteorological conditions associated with airborne spread of both pathogens included a shedding source population and prevailing winds, moving in the direction from the source facility to the surrounding facilities. In addition, cool temperatures, high relative humidly and low sunlight intensity were significantly associated with the airborne spread of PRRSV.  In conclusion, these results validate the use of air filtration as a means to reduce the risk of the airborne spread of 2 economically significant pathogens of pigs as well as identify risk factors associated with this event. It is hoped that this new information will help swine producers and veterinarians develop sustainable programs which target area/regional control and eventual elimination of PRRSV and Mycoplasma hyopneumoniae from the US swine herd.