Prairie dogs are not known to contract or transmit Hantavirus. It is only associated with deer mice (Peromyscus spp.), and some closely related species of rodents in the family Muridae. Prairie dogs are in an entirely different family of rodents, Sciuridae, and there are no known associations of hantavirus with prairie dogs and that association is not considered likely given that these species are not closely related.
Hantavirus is in our environment all the time, and we are probably exposed to minute amounts on a regular basis. It takes high concentrations of the virus in the air for someone to catch it. The primary time you should be concerned about Hantavirus is when you are cleaning (stirring up dust) in a closed-confined space where there is minimal air space, where small mouse droppings are present. The classic situation is when someone is cleaning an old closet or garage with a broom and the place has lots of droppings from deer mice. The best thing to do in that case is open the doors, wet the surface, and wear a mask. A full respiratory mask is required for protection from Hantavirus. Most mammalogists are not very concerned about contracting Hantavirus when trapping rodents because they are outdoors, exposed to the open air.