Rabies virus, conceptual image. Computer artwork of animal pawprints on a biohazard sign (yellow) representing the spread of the rabies virus (order Mononegavirales) by animals. The rabies virus is transmitted to humans from the bite of an infected animal. The virus infects the central nervous system, causing encephalopathy and ultimately death. Symptoms include fever, breathing difficulties, muscle spasms, and hydrophobia.