State health officials are growing concerned about Hantavirus, as the number of cases in Arizona has more than doubled this year.

Arizona usually sees about three cases of the virus annually. There have been seven cases so far this year and three people have died from it.

Arizona Department of Health Services Infectious Disease Director Joel Terriquez said the uptick is likely due to the increased snow and rain this year in certain parts of the state. That’s because there’s a better chance that rodents carrying the virus will come into contact with people.

“They’re gonna look for shelter and that basically increases exposure of humans to rodent excrete, saliva, urine, etc.,” Terriquez said.

The cases have popped up in Apache, Coconino, and Navajo counties. Symptoms of the virus can include fatigue, fever, muscle aches, and chills. Those can sometimes progress into pneumonia and even death.