The U.S. Department of Agriculture will spend the rest of emergency money it received to fight a deadly hog virus in 2014 on testing for the disease.

The change, announced in a notice issued on Monday, means the USDA will stop reimbursing farmers to implement measures, such as truck washing, to prevent infections of Porcine Epidemic Diarrhea virus (PEDv).

An outbreak of the virus, which causes severe diarrhea that kills baby pigs, wiped out up to 8 million hogs, a tenth of the nation's herd, three years ago, and drove pork prices to record highs. Farmers fear the disease could return this winter due to waning immunity levels in herds.

The U.S. government has "reprioritized its needs" for the use of money to combat the virus, according to the USDA notice.

In June 2014, USDA Secretary Tom Vilsack pledged $26.2 million to fight Swine Enteric Coronavirus Diseases, which include PEDv. The money included $11.1 million to cover the costs of improved cleaning measures at farms and $2.4 million for diagnostic testing.

The shift to only fund diagnostic testing should cover costs through this winter, the notice said.

A USDA spokeswoman had no immediate comment when asked about the reasons for the changes or how much money the agency had left to spend.

Diagnostic testing includes confirming cases of the virus in hogs and monitoring the progress that farms make cleaning up after infections, said Paul Sundberg, executive director of the Swine Health Information Center, an industry group.

The USDA is directing its remaining money "to the best manner possible to help the industry," he said.

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The USDA also will stop requiring farmers whose hogs have been infected with the virus to develop management plans to halt the spread of the disease.

"Those pieces that they took out either weren't being used to the full extent or they just weren't helping with the effort," Sundberg said about the USDA.

The USDA requires farmers and veterinarians to report cases of the disease to the government. The virus, which thrives in cold weather, has not caused major losses this winter.

Last year, the USDA temporarily fell behind inputting data on infections of the virus because it was busy responding to an outbreak of bird flu in poultry, an agency spokeswoman told Reuters in October.