With temperatures finally dropping, Montana’s short-lived bout with a deer-killing virus escaped the severity of states to the west.

About 60 deer that died in the Eureka area last month were believed to have been killed by the bluetongue virus, a disease that causes internal hemorrhaging and death in up to 80 percent of animals affected by it.

In Washington and Idaho, wildlife managers believe the virus was responsible for wiping out hundreds of deer.

The infection, to which humans and most other animals are immune, is spread by small biting insects called “midges” that typically die out after the first hard frost of the season.

Jennifer Ramsey, a Montana Fish, Wildlife and Parks wildlife veterinarian, said limited data exist on bluetongue disease, and whether an outbreak one year could resume the following year is an open question.

“I think that’s a big unknown,” she said. “We don’t really understand how this virus over-winters, exactly. Some years there will be an outbreak, but that doesn’t necessarily mean there will be an outbreak next year.”

Similarly, wildlife managers aren’t sure how to control the spread of the disease. Ramsey said spraying for the bugs is a possibility, but putting a pesticide into the environment could carry other consequences.

Additional samples from dead deer in Libby were sent to the state laboratory in Bozeman, but Ramsey said the virus was not detected. However, she noted that the quality of samples tend to be poor, and decomposition and scavengers can result in a false negative.