Pest control is of utmost importance to meat and poultry processors, but it also must be a top priority for growers, as shown by one study on the impact of flies on chicken flocks. The study’s results, published late last year, by the U.S. Department of Agriculture’s Agriculture Research Service (USDA-ARS), demonstrate the importance pest control plays in pathogen control.

The study shows that the common housefly can rapidly become contaminated with Salmonella eteritidis while residing in an environment with infected hens.

Previous studies show that different microbial pathogens can reside within the common housefly, and are typically spread via the fly’s defecation. Researchers believed prior to the study that was key to the housefly’s ability to transmit pathogens to susceptible hosts.

In this particular study, uninfected flies were introduced to birds that were infected with S. eteritidis. Within 24 to 48 hours of release into the room, a large percentage of flies was found to be contaminated with the pathogen, both on their exteriors and interiors, but primarily in the fly’s gut.

Researchers then introduced infected flies to rooms containing pathogen-free hens. Feed withdrawal was incorporated to induce molting in the hens and increase the potential for transmission to occur (as feed withdrawal has been shown to depress cellular immunity in the birds, according to the study).

After those flies were released into the room with the uninfected hens, however, they were only able to transmit S. eteritidis to one-third of the birds that ate the contaminated flies. Colonization of the pathogen followed in the intestines of the birds.

These results showed that flies exposed to an environment containing S. eteritidis, could become infected with the pathogen and might even serve as a source for transmission of S. eteritidis to other members of a flock, particularly if the birds eat the infected flies.

As such, poultry producers must step up their preventative measures to control S. eteritidis and prevent the infiltration of flies and other pests that might transmit pathogens quickly through their flocks.

The study referenced was performed by Peter S. Holt, Randle W. Moore and Richard K. Gast, of the USDA-ARS Egg Safety and Quality Research Unit, and Christopher J. Geden, of the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology.