Worldwide, rats and mice spread over 35 diseases. These diseases can be spread to humans directly, through handling of rodents, through contact with rodent feces, urine, or saliva, or through rodent bites. Diseases carried by rodents can also be spread to humans indirectly, through ticks, mites or fleas that have fed on an infected rodent. Here we suggest that you visit the link for the CDC which provides a pretty complete list of those diseases vectored from rodents directly and indirectly to man: http://www.cdc.gov/rodents/index.html