Rabies generally has a variable incubation period. The question actually refers to the incubation period of rabies. The duration of this period can vary widely; the shortest is about five days before onset of the disease, while the longest can reach up to eight years. The average incubation period is two to three months, with cases exceeding one year accounting for 2%-3% of instances. The length of the incubation period is related to factors such as the virulence of the virus, and the nerve distribution at the site of entry. The greater the amount of the virus, the stronger its virulence, and the richer the nerve supply at the site of entry, especially if it is closer to the central nervous system, the shorter the incubation period will be.