The State Department of Health and Human Services reports 20 outbreaks with 500 hundred illnesses since the start of the year.
Health officials said that's more than twice the number of outbreaks usually reported this time of year.
NBC Montana spoke with Gallatin County Health Department officials, who tell us keeping up with your personal hygiene is important to prevent spreading the virus.
We also caught up with one Bozeman senior who may have been a victim. Chuck Lange is a Gallatin County senior. Now he's the picture of health, but about a month ago Lange became violently ill.
Lange was not tested for Norovirus, but he did have all the symptoms -- evere stomach pain, nausea, vomiting and diarrhea.
"I was in Gallatin Rest Home for a month recently with the stomach virus. They had a hard time trying to figure out what it was," said Lange.
Gallatin County health officials say the Norovirus is extremely contagious and can easily spread from person to person. One way to prevent spreading the virus is by washing your hands and cleaning up any surfaces, to kill bacteria.
Matt Kelley, of the Gallatin County Health Department, says another way to prevent spreading the virus is to simply stay in your own home.
"If you're sick, you think you have the Norovirus, the best thing you can do is stay home," said Kelley. He says people who have the virus are still contagious days after symptoms have disappeared.
"If you know you have the Norovirus we tell you to stay home three days after your symptoms go away," explained Kelley.
Lange told us he was hospitalized for nearly a month with his stomach virus lingering. He says it took him weeks to bounce back to good health.
"I was in absolute misery for almost a month, before it ran its course," said Lange.
Health experts say people who are infected with Norovirus should not prepare food for others while they have symptoms and for three days after they recover from their illness.
They urge people to wash any linens or laundry that may have been in contact or contaminated. They also suggest you wash surfaces with hot water and a teaspoon of bleach to kill any lingering bacteria.
The Centers for Disease Control says Norovirus is highly contagious. Each year it is responsible for some 20 million cases of illness, hospitalizing 70,000 people and killing around 800.
Older adults and young children are the most susceptible.