Shell disease is a generic name for a variety of diseases that erode crustacean cuticle. To my knowledge, no one has isolated the cause of this in stomatopods. Also, once the shell starts to erode, a host of secondary infections set in - everything from protozoans and fungus to bacteria. The secondary infections can be treated with various dips, but stomatopods are so sensitive to a variety of organic and heavey metal treatments, that I don't recommend it. Cover (a good burrow), UV sterilization, and excellent water quality seem to be the answer. If the cuticle is not perforated, animals can recover, but if there are holes in the carapace or dorsal tergites, animals usually don't successfully molt.
By far the animals most likely to suffer from this syndrome are large male Odontodactylus sycllarus. I have seen it both in the field and in newly arrived animals, so it is not simply a function of captivity. Females can also get it, but it is less common. I think the vector is contagious in O.s., but only if conditions support its growth.
I have also seen similar diseases in Gonodactylus chiragra and Gonodactylaceous ternatensis, but it is less common. Typically, you find it in large animals that molt less frequently.
Roy