More cases of African swine fever (ASF) were confirmed in China last week, raising the total publicly reported cases there to at 15 as of late last week. To date, more than 38,000 pigs have been killed in China as a result of the disease.

The cases of ASF in China haven't affected the U.S. pork export market much, mostly because the United States hasn’t been exporting pork to China due to retaliatory tariffs on U.S. pork of 50 to 70 percent, says Dermot Hayes, an agricultural economist at Iowa State University.

However, the continued spread of the virus within China could shift supplies and demand, Hayes said.

“As more...