Yeah from mouse urine. This came to light at work about 15-20 years ago, especially in warm climates and people sleeping in tents, cabins, and so on with mice are at risk. Very dangerous.
Really importing snakes would be better or cats if Tester's method doesn't work. But really in this day and age, what's wrong with building a garage with tight doors?
The other day I saw a picture of that 5 gal pail of water with a ramp going up to it. A plastic Coke bottle on an axis is placed over the water and gobs of peanut butter on the center of the bottle. Mickey goes up the ramp, walks on the bottle to get to lunch and the bottle rotates and deposits Mickey in the water. Yeah its a dreadful death but what can you do? It can hold lots of dead mice before you have to empty it and add new water.