“That could be a big problem for food production stability,” Dr. Seifert said.
Health officials must stay vigilant, experts said.
The U.S.D.A. is now working with state agencies to collect blood samples and nasal swabs from dead deer in more than two dozen states. The work should help experts estimate how many deer have already been infected and whether certain characteristics, from age to habitat type, put some deer at elevated risk.
“As we learn more, we will continue to refine and target our surveillance,” said Dr. Tracey Dutcher, the science and biodefense coordinator for the Animal and Plant Health Inspection Service at the U.S.D.A.
Long-term genomic surveillance is also needed, experts said. “If we start to see some really divergent viral variants popping up in deer in certain places, that would be a red flag,” Dr. Goldberg said.
Depending on what scientists learn in the near future, officials could consider a variety of potential mitigation measures, including vaccinating captive deer, thinning infected herds or cleaning up whatever environmental viral contamination is giving the deer the virus in the first place.
“I think we’ve got to get our hands around the situation before we really make plans on where to go,” Dr. Bowman said.
For now, scientists also advise keeping a close eye on other wildlife. If the virus is so prevalent in deer, which are relatively easy to sample, it could be silently spreading in other species, too.
After all, the only reason scientists found the virus in deer is because they thought to look. “We hadn’t realized it was spread in deer at all,” Dr. Kapur said. “We had no clue.”
