Shipping Fever

Goats in a transport vehicle

The bushmeat trade is not the viruses’ only ticket around the world. More than 50 million live farm animals—cattle, sheep, and pigs—are traded across state lines in the United States alone every year, along with untold numbers of live birds on their way to slaughter.⁸⁶⁴ A pound of meat can travel a thousand miles “on the hoof” in the United States before reaching dinner tables.⁸⁶⁵ Live farm animal long-distance transport not only spreads disease geographically, but can make animals both more infectious and more vulnerable to infection.

According to the UN’s Food and Agriculture Organization, “Transport of livestock is undoubtedly the most stressful and injurious stage in the chain of operations between farm and slaughterhouse,” leading to significant “loss of production.”⁸⁶⁶ This stress impairs immune function, increasing the animals’ susceptibility to any diseases they might experience on their prolonged, often overcrowded journeys.⁸⁶⁷ Some pathogens that would not lead to disease under normal conditions, for example, become activated during transport due to stress-induced immunosuppression, triggering a wide variety of diarrheal and respiratory diseases. So-called “shipping fever,” the bovine version of which costs U.S. producers more than $500 million a year, is often caused by latent pathogens—including a SARS-like virus⁸⁶⁸ —which may become active when shipping live cattle long distances.⁸⁶⁹ Given the increased disease risk, the European Commission’s Scientific Committee on Animal Health and Animal Welfare recommends that “[j]ourneys should be as short as possible.”⁸⁷⁰

Once an animal is infected, the stress of transport can lead to increased shedding of the pathogen.⁸⁷¹ In one study at Texas Tech University, for example, the average prevalence of Salmonella within feces and on the hides of cattle was 18% and 6%, respectively, before transport. But cram animals onto a vehicle and truck them just 30 to 40 minutes, and the levels of Salmonella found in feces jumped from 18% to 46%; the number of animals covered with Salmonella jumped from 6% to 89% upon arrival at the slaughterplant, where fecal contamination on the hide or within the intestines can end up in the meat.⁸⁷² Similar results were found in pigs.⁸⁷³ The physiological stress of transport thus increases a healthy animal’s susceptibility to disease,⁸⁷⁴ while at the same time enhancing a sick animal’s ability to spread contagion.⁸⁷⁵

No surprise, then, that the FAO blames “[t]ransport of animals over long distances as one cause of the growing threat of livestock epidemics….”⁸⁷⁶ Dozens of outbreaks of foot and mouth disease, for example, have been tied to livestock movements⁸⁷⁷ or contaminated transport vehicles.⁸⁷⁸

The FAO describes live animal transport as “ideally suited for spreading disease” given that animals may originate from different herds or flocks and are “confined together for long periods in a poorly ventilated stressful environment.”⁸⁷⁹ Given the associated “serious animal and public health problems,” the Federation of Veterinarians of Europe have called for the replacement of the long-distance transportation of animals for slaughter as much as possible to a “carcass-only trade.”⁸⁸⁰