Hantavirus Prevention

In May, the Montana Department of Public Health and Human Services confirmed the first case of Hantavirus for 2016, in a Cascade County resident. Details of the case investigation suggest that the exposure may have occurred during the cleaning of a barn.

This is one of 43 Hantavirus cases reported in Montana since 1993. Montana typically sees 1 to 2 cases a year. Cascade County is the lead for Hantavirus infections in Montana. Hantavirus can cause severe illness and death, with 1 in 4 of Montana cases resulting in death. Cascade City-County Health Department (CCHD) wants to remind residents how to protect themselves against infection from Hantavirus.

Cleaning activities can disturb nesting materials contaminated with dried saliva, urine, or droppings from infected deer mice. The disturbed nesting materials become airborne and the air is inhaled causing an exposure to the virus. This exposure leads to a Hantavirus infection. A person might also be infected with Hantavirus if contaminated materials are directly introduced into broken skin or into the eyes or mouth.

Symptoms can begin one to six weeks after becoming infected with the virus. The illness typically starts with 3-5 days of “flu-like” symptoms including fever, sore muscles, headaches, nausea, vomiting and fatigue. Within a few days the illness rapidly progresses to severe shortness of breath.

Early diagnosis of Hantavirus and immediate medical care increase the likelihood of a full recovery. Individuals exposed to rodents or their waste who experience symptoms should immediately seek medical treatment and notify their provider that they have been around rodents or rodent wastes. Providing this information to your provider will help him or her to look closely for any rodent-carried disease, such as Hantavirus.

The best way to prevent Hantavirus transmission is by controlling rodent populations in areas where you live and work.

  • Seal up cracks and gaps in buildings that are larger than 1/4 inch, including window and door sills, under sinks around the pipes, in foundations, attics and any rodent entry hole.

  • Trap indoor rats and mice with snap traps, and remove rodent food sources.

  • Keep food (including pet food) in rodent-proof containers.


If you find places where rodents have nested, or if you find rodent droppings or waste, follow these steps to help to prevent exposure to Hantavirus while cleaning:

  • Wear rubber or plastic gloves

  • Thoroughly spray/soak area with a disinfectant or mixture of bleach and water to reduce dry dusty conditions in the area being cleaned (visit http://www.cdc.gov/rodents/cleaning/index.html or call 454-6950 and ask for a Public Health Nurse for specific mixing instructions)

  • Wipe or mop the area with a sponge or paper towel (throw away items after use)

  • Wash hands thoroughly with soap and warm water after removing gloves

  • Never sweep or vacuum in these areas as this can stir up dust and aerosolize the droppings

More information on Hantavirus and its prevention can be found by calling 454-6950 and asking to speak with a Public Health Nurse.