Sylvatic is a scientific term referring to diseases or pathogens affecting only wild (sylvan means forest-dwelling) animals. In the context of animal research, its opposite is domestic, which refers to pets, farm animals or other animals which do not dwell in the wild.
The word "sylvatic" is also simply a synonym for "sylvan" (or "silvan") = "of the forest".
The Latin words silvatica, silvaticus of this root are commonly used in biological taxonomy:Rana sylvatica (Wood Frog), agaricus silvaticus (Scaly Wood Mushroom), etc.
References
Sylvatic Wikipedia(Text) CC BY-SA