About one month ago, Washoe County (NV) health officials reported the first human hantavirus case since 2006 in a patient from south Reno.

Last week, health officials recorded the second case of hantavirus this year, an unusual occurrence because Washoe County has never recorded more than one case in any single year. In addition, this second case is the first recorded death of a Washoe County resident associated with the virus since 1995.

Peromyscus maniculatus (deer mouse) Image/CDC
Peromyscus maniculatus (deer mouse)

“A human case of hantavirus is extremely rare, but when it does occur, it can be deadly,” said Dr. Randall Todd, Director of the Washoe County Health District Epidemiology Program. CDC statistics indicate that on average 38% of hantavirus cases are fatal. “This fatality, the first in over 20 years, indicates the seriousness of this virus. We urge everyone to take precautions when cleaning, working, or recreating in areas where mouse droppings and/or urine may have collected. When waste particles are aerosolized by cleaning, sweeping, vacuuming, or tramping, and those particles are breathed in, people are at risk for contracting the virus.”

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The Health District is advising that people take extreme precaution when entering spaces where mice may have been, particularly during this time of year as the rodents seek shelter indoors from the colder outdoor temperatures. Statistics indicate that 30% of deer mice tested are carriers of hantavirus. “People cleaning for the holidays, retrieving decorations from storage spaces, and even people hunting and camping that are using cabins and campsites should be cautious,” Todd added.

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There are specific guidelines to follow when cleaning in areas with mouse activity:

  • Do not stir up dust by sweeping or vacuuming up rodent dropping, urine or nesting materials;
  • Always spray the area being cleaned with a disinfectant and let it set for five minutes before starting to work;
  • Wear protective clothing like gloves and a face mask to keep from touching and breathing in viral particles;
  • Set out traps to kill mice and other rodents;
  • Double-bag dead rodents in plastic sacks before disposing of them in the garbage; and,
  • Identify and plug openings that may allow rodents entry.  A deer mouse can fit through an opening the size of a nickel.  Plug holes using steel wool and put caulk around the steel wool to keep it in in place.

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Health officials stress that human cases of hantavirus infection are extremely rare, but can be deadly. The disease severely affects the lungs. Flu-like symptoms that can appear one to eight weeks after exposure can include muscle aches, particularly in the large muscle groups of the thighs, hips, back, and sometimes shoulders. Later symptoms include coughing and shortness of breath. Anyone with these symptoms after coming in contact with deer mice and their waste should seek medical attention immediately. Although there is no specific treatment, cure, or vaccine for hantavirus infection, if infected individuals are recognized early and receive medical care in an intensive care unit, they may do better.