The relationship between Smallpox and Cowpox was well known even in the 1700s. (Though the concept of infectious diseases was not understood until the late 1800s, the people who hung around cows a lot didn't die of Smallpox as much).
Turns out that Cowpox was the same viral-family as Smallpox, and that Cowpox could be used to lessen the effect of Smallpox.
So there were absolutely animal reservoirs of the Smallpox viral family. The disease was shown to hop from different species (from humans to cows and vice versa).
The relationship between Smallpox and Cowpox was well known even in the 1700s. (Though the concept of infectious diseases was not understood until the late 1800s, the people who hung around cows a lot didn't die of Smallpox as much).
Turns out that Cowpox was the same viral-family as Smallpox, and that Cowpox could be used to lessen the effect of Smallpox.
So there were absolutely animal reservoirs of the Smallpox viral family. The disease was shown to hop from different species (from humans to cows and vice versa).