The life cycle of the rabies virus is transmission, incubation, early symptoms (prodrome period) and encephalitis phase. Rabies is transmitted to a human or other animal through saliva from an infected animal, in which case transmission occurs from a bite or scratch. The final phases of rabies result in death.
The incubation period refers to the time period between exposure and the onset of symptoms. The length of time it takes the virus to reach the central nervous system can vary between three months to one year.
Early symptoms are similar to other illnesses and include headache, fever and discomfort. Encephalitis infection symptoms include muscle spasms, seizures and coma. Once a person or animal exhibits symptoms of rabies, the disease results in death.