Researchers confirm pig viruses can breeze in

Breezes can waft important pig diseases into barns, according to research at the University of Minnesota.

That confirms earlier suspicions and explains why air filtering systems have worked to keep herds free of diseases such as PRRS.

Three viral pig diseases, including influenza A, can be transmitted through aerosols carrying tiny particles of different sizes.

The findings are published in the Aug. 19 online edition of Public Library of Science (PLoS) One.

The researchers infected five-week-old piglets with the viruses, first PRRSV (Porcine Respiratory and Reproductive Syndrome Virus) and influenza A, then three weeks later with PEDV (Porcine Edidemic Diarrhea Virus).

Airborne sampling was done for 24 days, which also involved sorting the airborne particles according to size and testing the air samples for viruses. Investigators also tracked animals' clinical signs and other lab parameters.

Results showed that the sick pigs emitted all three viruses in a range of particle sizes that could be inhaled or swallowed.

However, for influenza and PRRSV, virus viability depended on size, with isolation possible only in particles larger than 2.1 micrograms.

PEDV, an enteric virus, was found in larger concentrations in the air than the other two viruses tested.

The group concluded that their findings support the role of aerosol transmission for the three viruses, that they can disperse at the same time through a range of particle sizes, and that they can be transmitted across both short and long distances.