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Livestock transportation promoted spread of PEDV
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Vehicles transporting pigs played a role in spreading porcine epidemic diarrhea virus, or PEDV, in the United States in 2013, according to recent findings.
“Pigs are commonly transported to harvest facilities in vehicles that have not been cleaned and disinfected between loads …” researchers wrote in Emerging Infectious Diseases. “In many cases, the risks and associated costs of disease introduced late in the growing period are thought to be less than the cost of cleaning and disinfecting vehicles. Transport vehicles are often shared by different pig owners, enabling the spread of disease across large regions.”
The researchers sought to determine the sources of potential transmission of PEDV, which spread swiftly across various regions of the United States in 2013.
In the study, investigators evaluated samples from 575 livestock transportation trailers before and after pigs were unloaded into holding pens (lairages) at six harvest facilities in the central United States. The researchers compiled information on each trailer, including the transport company and trailer identification, time of unloading, the dock used, whether transport personnel stepped on the dock, and whether workers entered the trailer. The researchers performed PCR analysis on the samples, which were collected from the floor of each of the trailers.
The researchers found that before unloading, 38 of the 575 (6.6%) trailers were contaminated with PEDV. Among the six harvest facilities, the percentage of contaminated trailers ranged from 2% to 14%. Of the 537 trailers that were not initially contaminated, 28 (5.2%) were contaminated during unloading.
Of the 38 trailers that were contaminated upon arrival to the facilities, samples from 13 (34.2%) were negative for PEDV after unloading. These samples generally had higher cycle threshold values than those from the 25 trailers that were PEDV-positive both before and after unloading. This suggests that in these trailers, PEDV may have been shed by previous loads of pigs transported to the facility by those trailers, rather than by pigs transported during the study period. For this reason, viral quantities may have been faintly detected or undetectable.
The rate of contamination during unloading was higher if the harvest facility workers entered the trailer (OR=4.15; 95% CI, 1.27-13.54) or if unloading transpired immediately after unloading another trailer that was contaminated (OR=3.35; 95% CI, 1.22-9.18). Harvest facilities that unloaded more trailers that were contaminated on arrival had higher contamination rates.
“This study of PEDV transmission by fomites should serve as an example of the risks that a modern, highly technical animal protein industry may encounter during a novel disease introduction,” the researchers wrote. “PEDV’s introduction and subsequent spread in the United States should spur action to minimize these risks before a disease that can affect international trade or food safety is introduced.”
Disclosure: Lowe owns Lowe Consulting Ltd. and Production Animal Consultation, LLC.
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