Very very very low. Bacteria and viruses are normally very sensitive to their hosts, they have a kind of symbiosis that means they can't just arbitrarily infect

Very very very low. Bacteria and viruses are normally very sensitive to their hosts, they have a kind of symbiosis that means they can't just arbitrarily infect any species they bump into. Jumping between species does happen, and when it happens it can be a big problem (see COVID-19, Swine Flu), but there is something like 100 million different virus species out there [1], and only 200 or so are able to infect humans [2]. Despite constant interaction between people and all other species of viral host all over the globe, and millions of brand new new virus exposures daily, jumps are still so rare that they are decade-defining when they happen. 1. https://virology.ws/2013/09/06/how-many-viruses-on-earth/ https://virology.ws/2013/09/06/how-many-viruses-on-earth/ 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3427559/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3427559/