This is another informative column. Good job, Drury!
A couple of suggestions:
Answer the damn questions BEFORE you get to the lengthy, though interesting, explanation of pox disease. One has four dense and difficult (difficult in terms of the amount of new information that you are presenting to your readers) paragraphs to get through before the questions is answered. I'm not sure that's neccessary.
Cut down on jargon whenever possible. If you tell us that the whatsitscalled comes in "wet form," why add it's scientific name ("fibrinonecrotic") or if you're referring to the bird's eyelid, why also mention the scientific term for eyelid ("conjunctivia"). We lay readers are working hard enough to follow the explanation already. Don't make our job more difficult than it is.
On the whole, however, you do an excellent job at explaining a rather arcane, technical disease in terms that regular folks can understand. Good work!