Mice are not your friends

By Chris Williams on April 29, 2016.

It just figures that since we’ve not had any snow on the ground for weeks that we would get a storm on the first full day of spring! I was looking back at my notes and three of the past four years we’ve had snow on or around the first day of spring.  But, enough about the weather, I really want to talk about mice.  I’m always amazed if a client tells me they don’t mind having a few mice around.  Really?  Of late, it certainly seems as if there is no such thing as a few’ mice.  The Northeastern US is not suffering from any shortage of mice.  Judging from the number of mice complaints regularly appearing in my work schedule, this is true.  I have yet to find any definitive explanations from researchers or industry experts as to why this explosion of mice is occurring. I’ve been at this a long time plus I have a long memory and I don’t recall them ever being out of control as they are now. Not only are they out of control, they’ve morphed from an unpleasant guest raiding the pantry to one that is regularly causing major property damage like disabling electrical systems in cars, and central air conditioning units.  I’ve met clients who TWICE have had mice chew through the plastic piping of their homes domestic water supply! And, just recently met with a client that had mice destroy some computer network cables in his home, knocking him offline and he works from home!  If those examples weren’t enough reasons why its’ not okay to share your dwelling with mice, some serious mouse-borne illness should do the trick.  Besides the increasing awareness of the importance of mouse urinary proteins (MUP) as a potent asthma trigger, there are two diseases that people need to be aware of.  One of these is Hantavirus which I first heard about way back in the mid 90’s.  Initial reports of an unknown and deadly pneumonia-like syndrome occurring in the ‘Four Corners’ region of the South Western United States were eventually linked to hantavirus in local rodent populations. A newly identified strain of hantavirus called Sin Nombre is responsible for causing hantavirus pulmonary syndrome (HPS). Hantaviruses had previously been known to cause human illnesses of varying severity in Europe and Asia (Grenon, Goldoff1997) but nothing like HPS where the average mortality rate for those affected is about 40 percent.  My initial thoughts about this were western strains of hantavirus in western rodent populations; so it’s not a problem, but in reality, the principle rodent reservoir for hantaviruses are the deer mice (Peromyscus maniculatus) and their geographic range extends to New England.  In fact there have been confirmed cases of HPS in New England ( linked to deer mice.  It has also now been determined that several strains of hantavirus are capable of causing HPS and have been found in some populations of the white-footed mouse (Peromyscus leucopus) as well. (  Hantavirus infections are not common, but certainly something to be aware about.

  • The other mouse borne disease getting some attention is lymphocytic choriomeningitis or LCM, which is carried by the common house mouse (Mus musculus) and can also be carried by ‘pocket pets’ like hamsters, mice, guinea pigs etc. Persons exposed to LCMV may or may not develop illness, and symptoms are flu-like in nature. Women who become infected with LCMV during pregnancy may have complications such as miscarriage. or the child may have severe birth defects. (
  • Other references:



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