(Updates with case in Quebec; details)
By Rod Nickel and Meredith Davis
WINNIPEG, Manitoba/CHICAGO, Jan 23 (Reuters) - Canada has discovered its first two cases of the Porcine Epidemic Diarrhea virus (PEDv), which has already killed more than 1 million pigs in the United States, government and industry officials said on Thursday.
The Ontario government is investigating a hog farm in the province's Middlesex County after a laboratory finding of the virus, Dr. Greg Douglas, chief veterinary officer for Ontario, said at a news conference. Middlesex County is in southern Ontario near the city of London.
Separately, one of Canada's biggest pork processors, Olymel LP, said tests also confirmed the virus at an unloading dock of its Saint-Esprit slaughter facility northeast of Montreal, Quebec.
"What they have found in the U.S. is this virus is highly contagious," Douglas said. "It has been very difficult for producers to absolutely mitigate the threat."
PEDv - which causes diarrhea, vomiting and severe dehydration in hogs - has turned up in 23 of the 50 states since its discovery in the United States last April.
The virus, which is already established in Europe and Asia, poses no threat to humans and is not a food safety risk, according to the Canadian Swine Health Board.
Canada is the world's third-largest pork shipper.
There are no official figures for pigs lost to the disease, but U.S. hog industry analysts estimate 1 million to 4 million have died.
The virus continues to spread in the United States, with a total of 2,394 confirmed cases in 23 states as of the week ended Jan. 18, according to the U.S. Department of Agriculture's National Animal Health Laboratory Network (NAHLN). As defined by the USDA, each diagnostic case could represent multiple animals at either a single farm site or several locations.
An undisclosed number of pigs have died at the Ontario farm. Douglas said the farm is not under quarantine, but the farmer has agreed not to move pigs off it in the near term.
Quebec and Ontario are Canada's two biggest hog-producing provinces.
Canadian hog farmers have been on high alert since the virus reached the United States last year, taking additional biosecurity measures such as washing out trucks returning from south of the border.
But the spread to Canada was seen as just a matter of time. The virus can spread through contaminated pig feces on pigs, trucks, boots and clothing.
Olymel spokesman Richard Vigneault said that, as a result of extra testing, the PED virus was discovered on Tuesday at the Quebec slaughter plant. The confirmed case did not affect production, he said in an interview with Reuters.
PEDv has no known implications for international pork trade, said Martin Rice, executive director of the Canadian Pork Council. In June, however, Mexico restricted imports of live hogs from the United States because of the deadly virus. (Editing by Andre Grenon, Marguerita Choy and Jonathan Oatis)