The ability of the PRRS (porcine reproductive and respiratory syndrome) virus to spread via aerosol depends on the dose level for the individual strain of the virus, according to an Iowa State University (ISU) research project.

ISU research indicates that different strains of PRRS virus have different dose levels needed for aerosol spread.

Thus, PRRS virus can transmit via aerosol, but each strain may react differently and this difference may help to explain why PRRS virus control on farm is difficult.

Furthermore, because the ability of PRRS virus transmission via aerosol depends on the exposure dose, provides some explanation as to how PRRS virus infection is maintained in swine populations.

Current and previous work conducted in an ISU laboratory resulted in these conclusions:
--The infectious dose for airborne PRRS virus isolate MN-185 is very low; and
--The infectious dose of airborne PRRS virus differs among isolates.

Funding for this project was provided by the National Pork Board.
Researcher: Jeffrey Zimmerman, DVM, Iowa State University. For more information, contact Zimmerman at