Several Mycoplasma spp. exist in tortoises. An infection with a virulent Mycoplasma agassizii strain causes the so-called upper respiratory tract disease (URTD), a disease clinically characterised by serous, mucous and purulent nasal discharge as well as ocular discharge, conjunctivitis and eyelid oedema. Furthermore, it can cause lethargy, dehydration, anorexia and fatal cachexia. An essential trait of mycoplasma infections is the fact that they can persist in the organism without triggering any symptoms. Often, the disease only breaks out if there are other microorganisms and environmental factors involved, combined with the genetic properties and immune reactions of the host.

Mycoplasmas are also detected in turtles and other reptiles, especially pythons, but little is known about their clinical relevance.