NFRS President replied saying
''Its Myco. Both rats and mice are infected after birth. I have always found it to be worse in mice though. Mice and rats can also get and transmit Sendai virus to each other. Sendai is much worse in mice as well. There are some others, like Pneumonia virus of mice, that rats can get as well.''
I shall ask if you should go ahead with getting rats or if that is unadvisable for now ?!!