...an un-determined rodent is the reservoir of this badly named pox viruse..it first came to light in 1958 when zoo monkeys in Copenhagen tested POS. Any mammal can catch this pox from an infected animal and spread it. Don't be too hard on the monkeys. There has been a documented case of a dog and cat catching this pox virus from a human. I hope this helps. People who have been vaccinated 30-40 years ago would no longer have any immunity and would need to be re-vaccinated.
(My reference is This Week in Virology, (TWiV) YouTube podcast by Prof. V. Racianello and Physician Dr. D. Griffin).