Hantavirus Cardiopulmonary Syndrome (HCPS) is a rare, but often fatal, lung disease. There are many hanta viruses but HCPS in the western U.S. is caused by the "Sin Nombre" virus (SNV). HCPS occur throughout the U.S. but are most commonly found in the southwest. In California deer mice are the only carriers of the SNV version of this disease. Other types of rodents rarely get infected so in this area of the country you wouldn't have to worry about them. Only deer mice.
You become infected when you breathe air that's contaminated by mouse urine or droppings when you are in a place with little air circulation. Examples can be in a corner, on shelves, or boxes in your barn, in cabins, trailers, or other buildings. Don't keep your woodpiles too close to your house. Same with trash.
Breathing small particles of mouse urine or droppings that have been stirred up into the air is the most common means of acquiring infection. The illness starts about a week or two after exposure and includes fever, headache, and muscle ache (especially the thighs, hips, back, and shoulders), and progresses rapidly to severe difficulty in breathing and, in some cases, death.
About 10% of all cases of the virus in the country have been identified in California and of those over 1/3 were fatal!
Avoid areas, especially indoors, where the mice are likely to have been present. This isn't possible if you are tasked with cleaning out the barn or shed! You can take precautions, and you should...think NO doctors if TSHTF...
Wear plastic gloves and spray areas contaminated with the droppings and urine with diluted bleach. If I'm going to clean out my barn I'll bring out the same bottle I use each night when I spray down my kitchen and the light switches and door knobs. Don't just sweep the waste out of the barn (like I normally did until I learned about this). Place it in double plastic bags. Tightly seal them and throw into the trash. Wash your hands thoroughly afterward.
If you have any dead mice don't touch them with your hands. Wear gloves. Prior to picking it up spray it with the diluted bleach and dispose of the same way as the droppings. Again wash your hands thoroughly.
What does the deer mouse look like? How do you know if it's a deer mouse or a house mouse that has left that pile of droppings or has made a nest in your barn? You won't know until you actually see the mouse. A deer mouse is about the same size as a house mouse. They are colored differently. A house mouse is a solid color - usually a light brown around here. Deer mice are grey to brown on top and white underneath. They also have large ears that don't have fur. Deer mice can be found throughout the state, not just where you'll find deer. While they prefer brush and shrubs, they will enter homes, barns, trailers, and other places looking for food, water, shelter, and nesting material.