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News from Wyoming Department of Health

Where Mice Have Been, Hantavirus is a Potential Threat


Hantavirus infection is a potential threat when mice infest garages, campers, cabins and barns and leave their droppings behind, according to the Wyoming Department of Health. 

Infected rodents shed hantavirus through urine, droppings and saliva. Hantavirus pulmonary syndrome (HPS) can affect people who breathe infectious aerosols created when dried materials contaminated by rodent urine and feces or saliva are disturbed. Infection is also possible when the virus is directly introduced into broken skin or mucous membranes, if it is ingested or after bites.

Eleven hantavirus cases, including six that resulted in death, have been reported in Wyoming since 1999. “While we may not see high case numbers, people should know hantavirus is dangerous and is sometimes fatal,” said Emily Thorp, an infectious disease epidemiologist with the Wyoming Department of Health. “Of note last year, there was a hantavirus outbreak in California that included 10 cases with three deaths among people who stayed in certain Yosemite National Park cabins.”

Thorp said mice getting in and around homes and outbuildings remains the biggest risk. Recommended cleanup guidelines include:

·   During cleaning, wear rubber, latex, vinyl, or nitrile gloves.

·   Spray rodent urine and droppings with a disinfectant or bleach solution until thoroughly soaked.  Combining 1 ½ cups of household bleach with 1 gallon of water is a good choice.

·   Do not vacuum or sweep urine, droppings, nesting materials or contaminated surfaces until they have been disinfected.

·   Use a paper towel (while wearing gloves) to pick up urine and droppings.

·   After the droppings and urine have been removed, disinfect items that might have been contaminated:

--- Mop floors with a disinfectant or bleach solution.
--- Disinfect countertops, cabinets, drawers and other durable surfaces with a disinfectant or bleach solution.
--- Spray dirt floors with a disinfectant or bleach solution.
--- Disinfect carpets with a disinfectant or with a commercial-grade steam cleaner or shampoo.
--- Steam-clean or shampoo rugs and upholstered furniture.
--- Wash potentially contaminated bedding and clothing with hot water and detergent and use gloves when handling it. Machine-dry laundry on a high setting or air dry in the sun.
--- Leave books, papers and other items that cannot be cleaned with a liquid disinfectant or thrown away in sunlight for several hours or in a clean indoor area for about one week so the virus is no longer infectious. Wear protective gloves and wipe the items with a cloth moistened with disinfectant.
--- Disinfect gloves before removing with disinfectant or soap and water. After removing the gloves, thoroughly wash bare hands with soap and warm water.

In places that are especially dirty, dusty or infested with mice, extra protective clothing or equipment should be worn such as coveralls, shoe covers and special face masks known as respirators.  If a building has been closed and unoccupied for a long time, doors and windows should be opened for ventilation at least 30 minutes before work begins.

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