Another challenge has been that the virus behaves differently on different farms. In some cases, the disease kills nearly ever baby pig during an initial outbreak, but more animals survive as time goes on. But other farmers get past the first outbreak, see herds start to recover and then have a new wave of illness as deadly as the first.
Vaccines, which several companies have in development, can help farmers fight the disease, but they also need to work with veterinarians and follow tight biosecurity procedures because several diseases similar to PED have emerged, said Lisa Becton, a veterinarian with the National Pork Board.
No data exist yet on how many animals have been killed by PED or how many farms have been infected. In April, the federal government began requiring farms to report outbreaks and is working on compiling those numbers. However, test results submitted by labs where farms send tissue and fecal samples indicate that the virus, which does not do well in heat, is spreading slower than it did last winter.
Chris Pardee, a health intelligence analyst with the iJET International consulting firm, praised the federal government for approving a vaccine and committing more than $26 million to fighting PED and similar diseases.
"It shows that a country is taking this seriously, that it is doing things to address the situation and that can really mean a lot when other countries are looking at the situation in the U.S. and considering trade bans or those types of responses," Pardee said.
Countries including France have stopped importing live pigs from the U.S. in recent months.