The porcine epidemic diarrhea virus (PEDV) hit Dave Struthers’ farm near Collins earlier this month, and it isn’t pretty. Pigs are sick — more than 80 have died — serving as an unwelcome reminder that PEDV remains as unpredictable and devastating to hog herds as when the virus first appeared in the United States nearly two years ago.

Struthers, the Iowa Pork Producers Association President, first saw symptoms of the virus in his finishing hogs just a few days before last week’s Iowa Pork ...