Key Messages

• 103 farrow-to-finish herds in England, Wales and Scotland were blood sampled (eight- and 14- week-old pigs and different parity sows).
• PRRSV antibodies were detected in 66 per cent of the herds (38.2 per cent non-vaccinated and 26.2 per cent vaccinated) with no difference between sow and pig farms (67 per cent and 66 per cent seropositivity).

Article Brief

A cross-sectional study was carried out in 103 farrow-to-finish pig herds to determine the prevalence of PRRS in Great Britain (GB). The 103 herds sampled in this study were representative of the national herd in size, location and ratio of indoor to outdoor pig herds in 2004.

The 103 herds sampled in this study were representative of the national herd in size, location and ratio of indoor to outdoor pig herds in 2004.

From each herd, 50 blood samples were collected: 10 from pigs eight and 14 weeks of age and five gilts and each of parity one, two, three, four and five or older.

All veterinarians of vaccinated herds stated that PRRS had been seen on the units, so both vaccinated and positive herds were included in the model as seropositive herds.

In total, 35 herds were found negative (34 per cent), then 39.8 per cent were seropositive and 26.2 per cent were vaccinated.

Herds were more likely to be negative if they were more than two miles away from the nearest pig unit (OR=3.42) or if they had more than 250 sows (OR=3.86). However, there may be a correlation with the farm size (smaller) and the production type (nucleus or multiplier versus commercial).

Negative farms are at risk of PRRSV introduction if geographically close to another pig farm, of larger herd size or if purchasing and/or not isolating incoming stock.

Reference

Evans C.M., Medley G.F. and Green L.E. 2008. Porcine reproductive and respiratory syndrome virus (PRRSV) in GB pig herds: Farm characteristics associated with heterogeneity in seroprevalence. BMC Vet. Res. 2008. 4:48.

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June 2015