Table 6 Exposure variables included in the risk factor analysis for PRRS infection

1. General farm information

Geographic location (by region)

Number of sites (one/multiple)

Herd size (measured by number of sows)

Pig density (total number of pigs within 10 km radius from the farm)

Farm type: outdoor/ indoor

2. Herd health

Farmers perception:

Herd vaccination program (PPV, PRRS)

Type of PRRS vaccine used (none/killed virus /live virus)

Results from serology and PCR:

Serological results: APP, SI (avian-like H1N1, H1N2, H3N2)

PCR results: PCV2 (PCR)

3. General management practices

Herd environment:

Ventilation type (natural/artificial/both)

Lightening (natural/artificial/both)

Presence of slurry system (yes/no)

Use of straw yards at any stage of the production (yes/no)

Presence of other animal species on the farm (yes/no)

Weaners stocking density/pen

Growers stocking density/pen

Finishers stocking density/pen

Herd management:

Number of movements between weaning and finishing

Mixing of pigs at any stage of the production (yes/no)

All in all out system at any stage of the production (yes/no)

Use of sick/hospital pens on farm (yes/no)

Routine cross-fostering performed (yes/no)

4. Genetics

Breed composition (percentage of breeds in the average finishing pig):

Large White (LW)

Landrace (LD)

Pietrain (P)

Duroc (D)

Hampshire (H)

Miesham (M)

5. Biosecurity

Possible route of disease introduction through people:

Number of people working on the farm

Average number of visitors/month

Number of days pig free

Use of protective clothes (yes/no)

Use of boot dips (yes/no)

Presence of fences around the farm (yes/no)

Allowed parking on the farm (yes/no)

Possible route of disease introduction through animals:

Purchase of boars (yes/no)

Purchase of gilts (yes/no)

Purchase of semen (yes/no)

Disposal of dead pigs (collection/incineration/other)