According to the DFW Wildlife Coalition, possums are highly resistant to a variety of animal diseases, such as distemper and rabies. Testing of wild possum populations has shown no recurring incidences of rabies. A common theory is that the possum's consistently low body temperature does not allow for the rabies virus to survive well. It is still very important to consult with a physician if bitten or scratched by a possum.
The National Opossum Society explains that possums generally pose a lower health risk to humans than dogs or cats. Possums have high immunity to disease and are more resistant to rabies than cows, goats, dogs, cats and sheep; however, this does not mean that they cannot potentially carry disease. Interaction with a possum should be avoided if possible.
According to the Washington Department of Fish and Wildlife, there is evidence that points to the possum as a potential carrier of the parasite that causes Equine Protozoal Myeloencephalitis, also referred to as EPM. EPM is a disease that is found in horses, and symptoms include spasms, dizziness and weakness. It is never a good idea for homeowners to feed possums, as this can cause the animals to lose their fear of humans and in turn become aggressive when their feeding needs are not met.