The average incubation period is between 30-90 days. Factors which may influence the length of the incubation period include the site of bite, the amount of virus in saliva of the batting animal, the virus strain, and the age and immune status of the victim. It is shorter in case the bite is closer to brain and massive dose of virus has been inoculated. Incubation period as short as 10 days and as long as 2 years have been reported.