By Meredith Davis Jan 30 (Reuters) - Confirmed cases of a deadly pig virus spreading across the U.S. Hog Belt jumped by 215 to its highest weekly increase since it was discovered in the country in April 2013, according to USDA's National Animal Health Laboratory Network. NAHLN announced the rise in cases of Porcine Epidemic Diarrhea virus (PEDv) on Wednesday. Each diagnostic case as defined by U.S. Department of Agriculture (USDA) could represent multiple animals at either a single farm site or several locations. PEDv, which causes diarrhea, vomiting and severe dehydration, is transmitted orally and through pig feces, but does not affect humans. Older pigs have a chance of survival, but the virus kills 80 to 100 percent of piglets that contract it. The virus has led to increasing costs for hogs, and at least one major maker of pork products has said it hurt the company's bottom line. The chief financial officer for Hillshire Brands Co, the Chicago-based maker of Jimmy Dean sausages and Ball Park hot dogs, said on Thursday during a conference call on second-quarter earnings that input costs were higher than expected partly due to increased sow prices. Average prices for live sows rose nearly 28 percent in the last year, according to U.S. Department of Agriculture data. "We watch very closely the number of new reported cases and we're very hopeful that one of the vaccines that are being developed will work," CFO Maria Henry said during the call. Chicago Mercantile Exchange lean hog futures deferred month contracts have risen on concerns the virus will decimate summer hog supplies. On Thursday, CME June hogs hit a contract high of 103.450 cents per lb, up 18 percent from the contract low in March 2013 before the virus broke. As of Dec 1. 2013, USDA data showed the nation's hog herd at 65.9 million head, down 1 percent from the previous year. Analysts attributed much of the loss to the spread of the fatal virus. The total number of confirmed cases has increased to 2,692 in 23 states as of the week that ended on Jan. 25. Nearly 40 percent of the cases -- 1,006 -- were confirmed in Iowa, the top U.S. pork producing state. () There are no official figures for pigs lost to PEDv but up to 4 million pigs may have died from the virus, according to industry analyst estimates. Additionally, the virus was confirmed in Canada last week. PEDv had spread to a fourth farm in the Canadian province of Ontario, the provincial government said on Wednesday, despite the industry efforts to stop it by disinfecting delivery trucks and clothing used on farms. PEDv has forced the U.S. hog industry to increase its biosecurity measures and has fueled concerns supplies will slump in the spring and summer.