Prevention of PRRSV infection in large breeding herds using air filtration

September 15, 2010 — 

In an article recently published in the Veterinary Record (Veterinary Record (2010) 166, 758-759 doi: 10.1136/vr.b4848), Drs. Gordon Spronk, Satoshi Otake and Scott Dee discussed the use of air filtration to prevent PRRS virus introduction into large breeding herds in swine dense areas.

In order to test this intervention in a commercial setting, a pilot study was conducted in seven large (greater than 3000 sows) breeding herds located in pig-dense regions of southern Minnesota and northern Iowa, USA. All seven herds had a history of annual PRRSV infections secondary to the introduction of new variants over the past four years, despite the use of industry-standard biosecurity practices for known routes of direct and indirect spread of the virus (Pitkin and others 2009). For the purpose of the present study, two of the seven herds (F-1 and F-2) were air filtered using technology described by Pitkin and others (2009), while the remaining five herds served as non-filtered controls (NF-1 to NF-5) (Table 1). Before filtration, the existing wildtype variant (PRRSV 1-18-2) had been eliminated from herds F-1 and F-2, resulting in PRRSV-negative status (Torremorell and others 2002). Filters were installed in the attic and both facilities used negative-pressure ventilation systems. F-1 used a total of 3660 EU 9 (MERV 16) filters, while F-2 used 1944 EU 8 (MERV 14) filters (Dee and others 2009b). These filters had been determined to be 95 percent and 75 percent efficient, respectively, at capturing particles greater than or equal to 0.3 μm in diameter.

Although further assessment of air filtration is required, involving a larger number of farms over a longer period of time, the results from this pilot study suggest that farms in dense regions of pig production are at risk of PRRSV airborne challenge and that the filtering of incoming air is an effective means to protect susceptible populations under highly challenging conditions, such as the area employed in this study.

G. Spronk, S. Otake, S. Dee, Prevention of PRRSV infection in large breeding herds using air filtration, Veterinary Record (June, 2010) 166, 758-759.