As was discussed in a prior post, we are into springtime, and while this can be a time of great renewal around our houses (spring cleaning and organizing) and in our yards (fresh flowers budding, new growth on trees), it is also a time that can be of great suffering for some people (hay fever, allergies to pollen and other wind-blown particulates).

[Image courtesy of seeks2dream on Flickr via a Creative Commons license]While deer mice, like this one, seem cute and innocent, some of them unknowingly carry a dangerous hantavirus, which has been known to make humans seriously ill or dead from inhaling mouse excrement particles.

The same pros and cons can be said for the animal kingdom in the spring – a time for renewal, like births of young, but also dangers because many predators come out after the winter to begin foraging for new good and re-establishing territory. And with some animals (including rodents and insects), the springtime can also be dangerous to humans, as the rodents and insects also become more active they tend to bring along some diseases that they host and harbor.

Like some of us take caution when it comes to pollen andother allergens, this is also the time of year that disease-carrying animals come out from winter hibernation. One of the most prominent ones in recent years have been the common deer mouse seen everywheree in rural and semirural areas of Canada and the U.S. (though some have been spotted in urban settings, as well). Deer mice have been known to be a carrier of the hantavirus, which is a very dangerous and potentially fatal virus to humans, and it comes from any excrement of an infected deer mouse (saliva, urine or feces).

This post is for those workers and companies that have work that puts workers around deer mice or any of their excrement – whether it is an abandoned house, a barn or some other environment where mice are expected to be present. While it’s estimated only about one in 10 deer mice are carriers of the hantavirus (and it is next to impossible to tell which ones are infected, as it seems the virus only lives in the mouse and does not actually infect in any way), it is always a good idea to understand hantavirus and what to do about preventing an infection whenever workers are around any mice droppings or urine – regardless of the breed of mouse, as it seems there may be other species of mouse that can be carriers or hosts of the virus.

What is hantavirus and how is it spread?

Hantavirus is primarily an airborne virus that causes a serious pulmonary disease in humans – something that starts as flue-like and can develop into something more like pneumonia. Symptoms can appear with an infected person, on average, from two weeks to a month after initial exposure, and there have been some cases of death happening within days of the symptoms first appearing.

The hantavirus, while not causing harm to the host mice, is transmitted through a mouse’s droppings, urine or saliva, and when a human inhales particulate matter in the air that stems from any of the mouse excrement.  So it’s not very important to actually see the mice in a location – it’s just knowing that there are souvenirs, so to speak, present or could be present that should alert workers and supervisors to have the proper respirators and equipment on hand to work around such souvenirs should they be seen, observed or known prior to entering a location.

What can we do about exposure?

Depending on the risk of exposure, many workers could use just personal protective equipment like gloves, goggles, air-purifying respirators (like simple facemasks) and sturdy shoes and long sleeves and pants to mitigate contact. The point is the risk of touching or inhaling anything that potentially came from a mouse that may be present. If a worker is entering a bulding that has been vacated for a period of time and has been infested with mice, then more advanced  protection may be required before workers can enter the property.

If there is a chance that your workers may be exposed to mice or their excrement, it is a very wise move to put a program in place and educate your supervisors and workers about the risks of exposure to mice, the proper protection wear and procedures for working  around mice, as well as reporting evidence of mouse activity on the worksite and/or documentation of any symptoms of illness that may be evident with a worker. And of course, in those situations where symptoms begin to manifest, speed is the key, so sending that worker to a hospital or medical clinic as quickly as possible is the best first option.

WorkSafeBC has circulated information contained in this PDF about hantavirus, mice and all of the general information that should be included in a rodent control program for your workers and supervisors on a worksite that may have rodents present.

The bottom line is to have a plan – do not treat hantavirus as surprise, or it may be too late.