The study, conducted by Prof Scott Dee, Satoshi Otake, Simone Oliveira and John Deen from the Swine Disease Eradication Center at the University of Minnesota College of Veterinary Medicine, USA was accepted in April and published in Veterinary Research.


Inoculation
A source population of 300 grow-finish pigs was experimentally inoculated with Porcine Reproductive and Respiratory Syndrome (PRRS) virus MN-184 and Mycoplasma hyopneumoniae (M. hyo)232 and over a 50-day period, air samples were collected at designated distances from the source herd using a liquid cyclonic collector.


Samples were tested for the presence of PRRSV RNA and M. hyoDNA by PCR and if positive, further characterised.


Of the 306 samples collected, 4 (1.3%) were positive for PRRSV RNA and 6 (1.9%) were positive for M. hyo DNA. The PRRSV-positive samples were recovered 4.7 km to the North West of the source population.


Samples
Four of the M. hyo-positive samples were obtained at the North West sampling point; two samples at approximately 2.3 km and the other two samples approximately 4.7 km from the source population. Of the remaining two samples, one sample was obtained at the South East sampling point and the other at the South West sampling point, with both locations being approximately 4.7 km from the source.


The four PRRSV-positive samples contained infectious virus and were > 98.8% homologous to the MN-184 isolate used to inoculate the source population. All six of the M. hyo positive samples were 99.9% homologous to M. hyo 232.


Long debate
The ability of livestock pathogens to be transported over long distances via aerosols has been debated for many years. In the literature, there are several reports of long-distance airborne spread of a number of bacteria and viruses including Foot-and-Mouth Disease virus (FMDV), Aujezsky’s disease virus (ADV), and M. hyo.


For the full study, click here.


Related article:
Identifying the routes of PRRS virus transmission