tjp, although the frog in the picture doesnt show any physical signs that I can see (and I would expect to be able to see lesions on it's legs) it is very possible that it did indeed succumb to "ranavirus" which is suspected to be caused by Aeromonas hydrophila.
Did you find this frog in your pond? Or is it actually an indoor pet? Sadly if it was in your pond you may find your entire amphibian population will be wiped out by this
I'm very sorry to hear that the frog is now dead could I direct you to this useful website on the subject Froglife/ranavirusinfo and I urge you to enter some details with them.
There is nothing you can really do i'm afraid, other than make sure you do not remove or relocate any amphibians or their spawn from your pond for a long time! Transferring anything to other ponds could be catastrophic for populations there also