Nidovirales is a classification of virus. As there are an enormous amount of Nidovirus types and mutant strains-it would be difficult to guess the replication rate of a standard type in a cold blooded organism...Regardless I would imagine it would show up on a PCR test within a few months as genetic tests are highly accurate and it only takes a minute amount of RNA/DNA to amplify.
Nidovirales are often enveloped (i.e. shielded) in a protein capsule. Sterilization of equipment (not disinfection) is required for complete destruction. Some of these viruses can last years and even decades outside of their hosts in the proper environments. Due to their durability these viruses are quite common as opportunistic infections.