No down-airstream Mycoplasmosis in tunnel vented houses, says study

Nov. 15, 2012, Champaign, IL – A new finding by government and academic researchers at Mississippi State University should help put turkey producers’ minds at ease about the possibility of the airborne transmission of a common bacterial agent for infectious sinusitis to their flocks from nearby poultry operations.  The researchers found that, even within a single tunnel-ventilated poultry house, the agent, Mycoplasma gallisepticum (MG), was unable to be transmitted even a short distance down-airstream to spread infection.
 
The new research findings of Dr. Joseph Purswell et al., appear in the December issue of Poultry Science, a journal published by the Poultry Science Association.  (The complete article is available for download at: http://dx.doi.org/10.3382/ps.2012-02619.)
 
“Because turkeys are more susceptible to MG infection than chickens, this has led to some concern among turkey growers that their birds could become infected by strains of the disease that might be carried from broiler and layer farms in their vicinity,” said Dr. Purswell, the article’s lead author and a researcher at the USDA-Agricultural Research Service at Mississippi State.  “Our work strongly suggests that this is a highly unlikely possibility.”
 
In the 1960s, the poultry industry suffered 30 per cent mortality rates in broilers due to Mycoplasmosis, and even today, concerns about the possibility of transmission of live MG from layer chickens to broilers, turkeys, and breeders continue to serve as an impediment to the permitted use of live MG vaccines in some multi-poultry-sector-dense states.
 
Experimental Design and Findings
 
The researchers’ objective was to compare transmission of uncharacterized layer complex-derived MG (LCD-MG) strains with commercially available, live F-strain MG (FMG) vaccine among poultry species in tunnel-ventilated housing.
 
In each of the two trials conducted, four commercial turkeys were housed in each of two adjoining pens that were immediately adjacent to air inlets.  The turkeys were inoculated with a dose of FMG in one trial, and with LCD-MG in the other.  In each trial, one pen was maintained with only four inoculated turkeys while a second pen contained the other four inoculated turkeys along with 16 MG-free broilers and 4 MG-free layers.  In addition, either four MG-free layers or four MG-free turkeys were placed down-airstream from the inoculated pens at a variety of distances, the nearest being only one empty pen between the inoculated and MG-free birds.
 
At the end of the 106-day trial period, the researchers found that neither the commercial FMG vaccine strain nor the LCD-MG strains were transmitted beyond the pens containing the inoculated turkeys.
 
According to Dr. Purswell, the results of the study “support the notion that the F strain of MG is no more transmissible than other endemic field strains of MG.”