Researchers float theory on how recent pig viruses, including PED, arrived in North America

Saturday, October 3, 2015

By SUSAN MANN

Researchers looking for answers on the root causes of the swine enteric coronavirus’ introduction in the United States have uncovered some key differences in Canadian and American government regulations concerning the use of pet food scraps and salvage material that may indicate why the disease broke out there first.

In Canada, farmers are prohibited from feeding livestock pet food scraps or salvaged material such as waste, damaged or outdated pet food.

But in the United States, such products are fair game when “prices are economically beneficial,” says a September report from the United States Department of Agriculture Animal and Plant Health Service.

The leeway in the United States in turn means that feed mills and others can the reuse large, flexible bulk containers often used for importing various products from overseas (such as sand for flood control, soybeans and pet treats) without having to be concerned about feed contamination.

In its report, the USDA study team identified the containers as the most likely scenario out of 17 for the virus to have arrived stateside. However, the team didn’t find definitive proof any one of the scenarios explored — including the containers — was the virus’s route of travel.

Once they are emptied of their imported contents, the containers are reused within U.S. borders to carry various products, including bulk feed or ingredients for pig rations to feed mills. They aren’t cleaned or disinfected between uses. Once a contaminated bulk container or its contents are delivered to a local pig feed manufacturer, the container or its contents would contaminate the feed or ingredients destined for delivery to farms, the report says.

The virus could easily remain stable through the time needed to travel to the United States and infect pigs, says the report, which is called Swine Enteric Coronavirus Introduction to the United States: Root Cause Investigation.

Ontario Pork officials declined to comment on the report. Mary Jane Quinn, communications and marketing manager, says by email, “Ontario Pork does not have anything to add to this.”

The containers come in various sizes, usually carrying 1,000 to 3,000 pounds, and “are designed to be reused,” the 53-page report says. They are made of woven polypropylene and may also have an internal liner.
 
The containers, called flexible intermediate bulk containers or tote bags, may have been contaminated in their country of origin by various methods, such as being transported on contaminated trucks, exposed to irrigation or flood waters containing organic fertilizer (pig manure), by organically grown soybeans, birds or various other products.

The two products that had the opportunity to be contaminated in other countries and exported to the United States in the containers were organic soybeans and pet treats. The United States imports organic soybeans in bulk for both human and animal consumption from India and China, the report says.

During the first quarter of 2013, 4.6 million kilograms (4,600 tonnes) of pet treats were shipped to the United States from China. They came from companies located adjacent to the swine-dense parts of China where the “closest ancestors of United States strains of the SECD (swine enteric coronavirus disease) virus were first reported,” the report says.

Between April and August 2013 there were three novel swine enteric coronavirus disease viruses entering the United States at the same time or within a few months of each other, the report says. “These may have arrived together or separately, but likely via the same mechanism,” the report says.

The viruses first showed up on a U.S. pig farm in Iowa in April 2013.

The viruses, including porcine epidemic diarrhea virus, also showed up in Ontario, likely through contaminated piglet feed ingredients. Since the first case was confirmed on a Middlesex County farrow-to-finish farm on Jan. 22, 2014, there have been 84 confirmed cases. The most recent one was July 14 on a Lambton County farrow-to-finish operation. BF