Researchers Demonstrate Potential Routes of Transmission of Salmonella and Campylobacter in Turkeys

Salmonella and Campylobacter could be transmitted by insect pests, rodents and contaminated semen, research at North Carolina State University has shown. Sanitising eggs reduced Salmonella counts on eggshells but a probiotic fed to turkey breeders and meat birds did not cut levels of either pathogen.
calendar icon 31 March 2014
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Current USDA FSIS regulations require turkey processing companies not to exceed established low limits of Salmonella and Campylobacter in processed products, as monitored by testing programmes.

A number of methods including chemical interventions are used to control these pathogens in the plants. However, reducing or eliminating both pathogens from birds prior to processing is potentially a more cost effective method than excessive plant interventions. The entry, transmission and overall prevalence of both pathogens in the production chain must be understood in order for appropriate interventions to be instituted. Although these pathogens are frequently found colonising the intestinal tract of poultry, they have also been isolated from the avian reproductive tract, indicating a possible source of contamination of hatching eggs and resulting progeny. These mechanisms have been studied in broilers, but less so in turkeys.

The objectives of this project, report Doug Smith of the Prestage Department of Poultry Science at North Carolina State University and co-authors there and the USDA ARS Richard B. Russell Research Center were:

  • to determine routes of transmission for Salmonella and Campylobacter throughout turkey production and processing and
  • to determine effects of selected interventions on prevalence and numbers of Salmonella and Campylobacter.

Sponsored by the US Poultry & Egg Association Harold E. Ford Foundation, the project included growing and monitoring of turkey breeder hens and toms to 65 weeks of age, artificial insemination and collection of fertile eggs for hatching a second-generation meat bird flock, and then monitoring these progeny (meat bird flock). Intervention assessments included washing fertile eggs with sanitiser and feeding probiotics to both breeder hens and meat bird progeny.

Monitoring results showed that Campylobacter spread rapidly and cross-contaminated turkeys throughout the grow-out house. For both Salmonella and Campylobacter, wild strains that appeared seemed to out-compete marker strains after a few weeks and persist in the flock.

The most common wild strains were Campylobacter jejuni (tetracycline-resistant), Campylobacter coli (kanamycin-resistant) and Salmonella Agona.

Pathogens were also isolated from pest vectors (flies, beetles and a rodent) in the houses, confirming the importance of proper pest control and biosecurity to control the spread of the bacteria.

Vertical transmission of these pathogens through hatching eggs was not demonstrated in this study, however, marker Salmonella inoculated in semen was found in the upper reproductive tract of breeder hens. Furthermore, wild strains of both pathogens were isolated from semen and wild Campylobacter strains were also isolated from the upper reproductive tract of breeder hens, indicating a potential route of transmission to progeny.

Results from the interventions indicate a positive effect of washing and sanitising eggs that may decrease the prevalence of Salmonella detected on the eggshell.

The application of a feed probiotic treatment (Primalac®) at high dosage for two weeks prior to slaughter was not found to significantly reduce the prevalence of Salmonella and/or Campylobacter in caeca for either breeder hens or meat bird progeny tested.

This study demonstrates the potential role of poultry house pests in the spread of both Campylobacter and Salmonella in turkeys, conclude Smith and his co-authors. Further, it indicates a possible route of transmission of these pathogens via the insemination of contaminated semen.

They add that results indicate sanitising hatching eggs will reduce the levels of eggshell contamination by Salmonella.

In this study, use of a probiotic in breeders or meat turkeys did not reduce the levels of Salmonella or Campylobacter detected.

March 2013

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