Researchers worldwide are uniting to prevent the spread of the porcine epidemic diarrhea virus (PEDV).

PEDV is devastating hog farms across the U.S., with nearly 200 farms reporting outbreaks. The virus is often fatal for young pigs, though older pigs tend to have higher survival rates. Read more here.

The United Kingdom first identified PEDV in their hogs in 1971, but after several outbreaks, the hogs there gained immunity to the virus. However, the virus since has entered Asia, and now, it is present in 14 states in the U.S. The USDA tried to prevent the virus from entering the U.S. by halting pig imports from Asia, but this didn’t stop PEDV from seeping into American farms.

The question puzzling researchers is how the virus got into the U.S.

A team led by Douglas Marthaler, a scientist at the University of Minnesota, investigated the virus genome from a sample of the virus taken from a Colorado farm. The researchers found it to be 99.4 percent identical to the Chinese strain of PEDV. This discovery provides few answers, because the U.S. doesn’t import hogs from China. Canada, the primary source for U.S. hog imports, isn’t the gateway either, because Canada also refuses to import pigs from China.

It is unknown how long the virus can survive outside a pig’s intestines in feces, so it is possible that even a dirty boot could be the cause of this epidemic.

Trying to find a vaccine for the disease presents its own challenges. Scientists must first be able to recreate the virus in the lab. This is a difficult task, because the virus only thrives in the special environment created in pig intestines. While scientists in Europe and Asia have managed to recreate the virus, American scientists can’t receive their samples because of biosecurity safeguards preventing the transport of viruses between countries.

Read more here.