RABIES

also called hydrophobia, or lyssa acute, ordinarily fatal, viral infectious disease of the central nervous system. The disease is usually spread among domestic dogs and wild carnivorous animals by a bite; all warm-blooded animals are susceptible to rabies infection. The virus, a rhabdovirus, is often present in the salivary glands of rabid animals and is excreted in the saliva; thus, the bite of the infected animal introduces the virus into a fresh wound. Under conditions favourable to it, the virus becomes established in the central nervous system by propagation along nerve tissue from the wound to the brain. When infection occurs, the disease develops most often between four and six weeks after exposure, but the incubation period may vary from 10 days to eight months. The disease often begins with excitation of the central nervous system expressed as irritability and viciousness. During the early stages a rabid animal is most dangerous because it appears to be healthy and may seem friendly but will bite at the slightest provocation. Wild animals that appear to be tame and that approach people or human habitations in the daytime should be suspected of having rabies.