Hantavirus pulmonary syndrome (HPS) is a very rare but serious disease that can be carried by deer mice and some other rodents. Deer mice are not born with the virus, but if they contract it they may pass it to humans. The virus is airborne and transmission is usually through breathing the dust from the mouse's feces, urine and saliva. An infected mouse will not develop any symptoms, but infected humans will develop severe respiratory problems that require immediate medical attention. Most cases of the disease have been reported in the dry climate of the Four Corners region of Utah, Colorado, New Mexico and Arizona.
Hantavirus is a newly discovered virus and there is little information available. The virus was first identified in 1993 in the Four Corners area when a number of cases were reported in a short period of time. Between then and December 31, 2011 a total of 587 cases of HPS have been reported to the CDC. Thats an average of 44 cases a year across the country.
If you wish to have your pet mouse tested for HPS, I'm sorry, that is not possible. The CDC tests mice, but the test is fatal to the mouse and they will not take requests from individuals. Requests for testing are only accepted from government officials and health professionals.
I cannot tell you the risk of keeping deer mice as pets. There are a number of factors, not all of them known to me. I can tell you there are a lot of fear mongers out there that make it sound like touching a deer mouse is the kiss of death. A while back I read a post on a forum by a woman who found a dead mouse in her driveway. She sounded like her whole family were doomed. Fear is not a substitute for legitimate information. Talk to your doctor; when I told my doctor that I kept pet deer mice, she wasn't at all concerned. Your doctor may have a different opinion. Consider this observation; according to the US Census Bureau there are over 130 million housing units in the country with an average occupancy of 2.3 people each. If 1% of those houses are shared with uninvited deer mice, living in close proximity to the human occupants, that would potentially expose about 3 million people to hantavirus. Yet the number of reported cases is still only 44 per year. That is less than the chance of being struck by lightning, but greater than the chance of being involved in a shark attack. I guess it's a good thing that sharks can't enter your house surreptitiously. Decide for your self.
As for me, I'd be more concerned about having a current tetanus shot. While deer mice rarely bite, they can and sometimes do, especially when frightened or injured, and they can bite very deep for such a small animal. They have teeth about a quarter inch long and can make a deep and bloody puncture wound. Fortunately they don't do this often. In the dozen or so years I have kept deer mice I have been bitten twice to the point of drawing blood, both times by mice in distress. The first time I ended up running for the bathroom, dripping blood all the way. Get a tetanus shot.
If you are concerned about HPS it is important to review the most current research. Visit the sites listed for more information. The CDC publishes HPS statistics by state. Most states east of the Mississippi have a very low number of reported cases. Many pest control sites talk about hantavirus. Keep in mind they are selling a service and may exaggerate the risk. I've only listed information from responsible health care professionals and agencies.