Are there hidden virus' and bacteria in the world that we just haven't come into contact with, yet? Probably, but I doubt it would have to do with reptiles as carriers. Asians have been eating reptiles since before any European cultures even existed. More likely, it's because virus' are evolving in the face of modern medicine and technology.
I doubt that Chinese people eat Mandarin ratsnakes. They mainly eat the larger snakes, such as the stripe-tailed rats and copperheaded rats, etc.