The incubation period for rabies is one to three months, and it is rare for it to exceed one year. The length of the incubation period for rabies varies, the shortest being about five days and the longest can reach up to eight years, with an average incubation period of one to three months. Cases exceeding one year account for about 2%-3%. The length of the incubation period for rabies is closely related to several factors including the virulence of the virus, and the nerve distribution at the site of entry. The more viruses there are, the stronger their virulence, and the richer the nerve supply at the entry site, especially closer to the central nervous system, the shorter the incubation period.